Question: what is the role of t tubules

What is the T tubules function in muscle contraction? What is the T tubules function in muscle contraction?
Asked by: Ibrahym Antinori
What is the T tubules function in muscle contraction?
 The function of T-TUBULES is to conduct impulses from the surface of the cell (SARCOLEMMA) down into the cell and, specifically, to another structure in the cell called the SARCOPLASMIC RETICULUM. Click to see full answer. In this way, what are T tubules in muscle? T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. Similarly, do T tubules have voltage gated channels? Action potentials are conducted into the interior of muscle fibers via the T-tubules and there activate voltage-gated channels known as dihydropyridine receptors (DHPR). Unlike in cardiac muscle, very little calcium enters the muscle fiber from the extracellular space (via the DHPR). Regarding this, how would you explain skeletal muscle cell contraction were there no T tubules? 2012).

What is the T tubules function in muscle contraction?

What is the T tubules function in muscle contraction?
Asked by: Ibrahym Antinori
What is the T tubules function in muscle contraction?

The function of T-TUBULES is to conduct impulses from the surface of the cell (SARCOLEMMA) down into the cell and, specifically, to another structure in the cell called the SARCOPLASMIC RETICULUM. Click to see full answer. In this way, what are T tubules in muscle? T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. Similarly, do T tubules have voltage gated channels? Action potentials are conducted into the interior of muscle fibers via the T-tubules and there activate voltage-gated channels known as dihydropyridine receptors (DHPR). Unlike in cardiac muscle, very little calcium enters the muscle fiber from the extracellular space (via the DHPR). Regarding this, how would you explain skeletal muscle cell contraction were there no T tubules? 2012).

What is the T tubules function in muscle contraction? What is the T tubules function in muscle contraction?
Asked by: Ibrahym Antinori
What is the T tubules function in muscle contraction?
 What is the T tubules function in muscle contraction? Asked by: Ibrahym Antinori
asked in category: General Last Updated: 24th January, 2020
What is the T tubules function in muscle contraction? The function of T-TUBULES is to conduct impulses from the surface of the cell (SARCOLEMMA) down into the cell and, specifically, to another structure in the cell called the SARCOPLASMIC RETICULUM. Click to see full answer. In this way, what are T tubules in muscle? T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell.

What is the T tubules function in muscle contraction? Asked by: Ibrahym Antinori
asked in category: General Last Updated: 24th January, 2020
What is the T tubules function in muscle contraction? The function of T-TUBULES is to conduct impulses from the surface of the cell (SARCOLEMMA) down into the cell and, specifically, to another structure in the cell called the SARCOPLASMIC RETICULUM. Click to see full answer. In this way, what are T tubules in muscle? T-tubules (transverse tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell.

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What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
5 Answers
Calcium flows through t-tubules.
In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell. In skeletal muslce it contributes greatly to muscle contraction.
The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction.
This Site Might Help You.
RE:
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
The T-tubules are part of the triad that interconnect the sarcoplasmic reticulum (SR). They make contact with the terminal cisternae of the SR.
Their function is to conduct the action potential throughout the muscle fiber, deeper into the muscle for contraction.
How do you think about the answers? You can sign in to vote the answer.
 In skeletal muslce it contributes greatly to muscle contraction. The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction. ...Show more
Source (s): Degree in molecular biology and am currently in medical school. Garrott
6 years ago
This Site Might Help You. RE: What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? ...Show more
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What is the function of the t-tubules in a muscle contraction? | Yahoo Answers

What is the function of the t-tubules in a muscle contraction?
Trending News
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
5 Answers
Calcium flows through t-tubules.
In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell. In skeletal muslce it contributes greatly to muscle contraction.
The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction.
This Site Might Help You.
RE:
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
The T-tubules are part of the triad that interconnect the sarcoplasmic reticulum (SR). They make contact with the terminal cisternae of the SR.
Their function is to conduct the action potential throughout the muscle fiber, deeper into the muscle for contraction.
How do you think about the answers? You can sign in to vote the answer.

In skeletal muslce it contributes greatly to muscle contraction. The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction. ...Show more
Source (s): Degree in molecular biology and am currently in medical school. Garrott
6 years ago
This Site Might Help You. RE: What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? ...Show more
Source (s):

What is the function of the t-tubules in a muscle contraction? | Yahoo Answers What is the function of the t-tubules in a muscle contraction?
Trending News
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
5 Answers
Calcium flows through t-tubules.
In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell. In skeletal muslce it contributes greatly to muscle contraction.
The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction.
This Site Might Help You.
RE:
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
The T-tubules are part of the triad that interconnect the sarcoplasmic reticulum (SR). They make contact with the terminal cisternae of the SR.
Their function is to conduct the action potential throughout the muscle fiber, deeper into the muscle for contraction.
How do you think about the answers? You can sign in to vote the answer.
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the_man_60
asked in Science & Mathematics Biology · 1 decade ago
What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? 5 Answers
Relevance
Sondra
1 decade ago
Favorite Answer
Calcium flows through t-tubules. In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell. In skeletal muslce it contributes greatly to muscle contraction. The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction. ...Show more
Source (s): Degree in molecular biology and am currently in medical school.

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the_man_60
asked in Science & Mathematics Biology · 1 decade ago
What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? 5 Answers
Relevance
Sondra
1 decade ago
Favorite Answer
Calcium flows through t-tubules. In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell. In skeletal muslce it contributes greatly to muscle contraction. The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction. ...Show more
Source (s): Degree in molecular biology and am currently in medical school.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 The purpose of this review is to provide an overview of recent studies of t-tubule structure and function in cardiac myocytes. The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane that occur at the Z line and have both transverse and longitudinal elements. Many of the proteins involved in excitation-contraction coupling appear to be concentrated at the t-tubules. Therefore, it has been suggested that the t-tubules play a central role in cell activation. In the present review, we will consider the immunohistochemical and functional evidence for protein localization at the t-tubules, potential problems in the interpretation of such data, and the functional consequences of such localization. We will also consider the possible role of the t-tubules in the functional changes that occur during cardiac development, hypertrophy, and failure. Occurrence and Morphology of the T-Tubules
T-tubules are present in the cardiac tissue of all species of mammals so far investigated (eg, mice, 1 rats, 2 guinea pigs, 3 rabbits, 4 dogs, 5 pigs, 1 and humans 6) but appear to be absent in avian, 7 reptile 8 and amphibian 8 cardiac tissue. Within mammalian cardiac tissue, t-tubules occur predominantly in ventricular myocytes, being either absent or far less developed in atrial, pacemaking, and conducting tissue, 9 although a recent report has suggested that ≈50% of atrial myocytes possess a sparse irregular tubular system. 10 The following discussion will concentrate on mammalian ventricular myocytes. The t-tubules are invaginations of the sarcolemma and glycocalyx, which appears to remain associated with the sarcolemma within the t-tubules.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research

T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References

The purpose of this review is to provide an overview of recent studies of t-tubule structure and function in cardiac myocytes. The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane that occur at the Z line and have both transverse and longitudinal elements. Many of the proteins involved in excitation-contraction coupling appear to be concentrated at the t-tubules. Therefore, it has been suggested that the t-tubules play a central role in cell activation. In the present review, we will consider the immunohistochemical and functional evidence for protein localization at the t-tubules, potential problems in the interpretation of such data, and the functional consequences of such localization. We will also consider the possible role of the t-tubules in the functional changes that occur during cardiac development, hypertrophy, and failure. Occurrence and Morphology of the T-Tubules
T-tubules are present in the cardiac tissue of all species of mammals so far investigated (eg, mice, 1 rats, 2 guinea pigs, 3 rabbits, 4 dogs, 5 pigs, 1 and humans 6) but appear to be absent in avian, 7 reptile 8 and amphibian 8 cardiac tissue. Within mammalian cardiac tissue, t-tubules occur predominantly in ventricular myocytes, being either absent or far less developed in atrial, pacemaking, and conducting tissue, 9 although a recent report has suggested that ≈50% of atrial myocytes possess a sparse irregular tubular system. 10 The following discussion will concentrate on mammalian ventricular myocytes. The t-tubules are invaginations of the sarcolemma and glycocalyx, which appears to remain associated with the sarcolemma within the t-tubules.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 2003;92:1182–1192
Abstract
The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane. Recent studies have suggested that the structure and function of the t-tubules are more complex than previously believed; in particular, many of the proteins involved in cellular Ca 2+ cycling appear to be concentrated at the t-tubule. Thus, the t-tubules are an important determinant of cardiac cell function, especially as the main site of excitation-contraction coupling, ensuring spatially and temporally synchronous Ca 2+ release throughout the cell. Changes in t-tubule structure and protein expression occur during development and in heart failure, so that changes in the t-tubules may contribute to the functional changes observed in these conditions. The purpose of this review is to provide an overview of recent studies of t-tubule structure and function in cardiac myocytes. The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane that occur at the Z line and have both transverse and longitudinal elements. Many of the proteins involved in excitation-contraction coupling appear to be concentrated at the t-tubules. Therefore, it has been suggested that the t-tubules play a central role in cell activation. In the present review, we will consider the immunohistochemical and functional evidence for protein localization at the t-tubules, potential problems in the interpretation of such data, and the functional consequences of such localization.

2003;92:1182–1192
Abstract
The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane. Recent studies have suggested that the structure and function of the t-tubules are more complex than previously believed; in particular, many of the proteins involved in cellular Ca 2+ cycling appear to be concentrated at the t-tubule. Thus, the t-tubules are an important determinant of cardiac cell function, especially as the main site of excitation-contraction coupling, ensuring spatially and temporally synchronous Ca 2+ release throughout the cell. Changes in t-tubule structure and protein expression occur during development and in heart failure, so that changes in the t-tubules may contribute to the functional changes observed in these conditions. The purpose of this review is to provide an overview of recent studies of t-tubule structure and function in cardiac myocytes. The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane that occur at the Z line and have both transverse and longitudinal elements. Many of the proteins involved in excitation-contraction coupling appear to be concentrated at the t-tubules. Therefore, it has been suggested that the t-tubules play a central role in cell activation. In the present review, we will consider the immunohistochemical and functional evidence for protein localization at the t-tubules, potential problems in the interpretation of such data, and the functional consequences of such localization.

 T-tubule - Wikipedia
T-tubule
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Invagination of the plasma membrane of a muscle cell that extends inward from the cell surface around each myofibril; the ends of T-tubules make contact with the sarcoplasmic reticulum membrane
T-tubule
Skeletal muscle, with T-tubule labelled in zoomed in image. T-tubule structure and relationship to the sarcoplasmic reticulumin skeletal muscle
Details
Part of
Cell membraneof Skeletal muscleand cardiac musclecells. Identifiers
Latin
tubulus transversus
TH
H2.00.05.2.01018, H2.00.05.2.02013
Anatomical terminology
[edit on Wikidata]
T-tubules(transverse tubules) are extensions of the  cell membrane that penetrate into the centre of skeletaland cardiac musclecells. With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potentialinto the cell, and also play an important role in regulating cellular calcium concentration. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell.[1] T-tubule structure may be affected by disease, potentially contributing to heart failureand arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1Structure
1.1Regulators
2Function
2.1Excitation-contraction coupling
2.2Calcium control
2.3Detubulation
3History
4Clinical significance
5See also
6References
Structure[edit]
T-tubules are tubules formed from the same phospholipid bilayeras the surface membrane or sarcolemmaof skeletal or cardiac muscle cells.[1] They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma.[1] Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system.[2] The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. [ 1]
T-tubules are found in both atrialand ventricularcardiac muscle cells (cardiomyocytes), in which they develop in the first few weeks of life.[3] They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.[4] In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discswhere the actin filaments anchor within the cell.[1] T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulumin specific regions referred to as terminal cisternae.

What is the function of the t-tubules in a muscle contraction? | Yahoo Answers What is the function of the t-tubules in a muscle contraction?
Trending News
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
5 Answers
Calcium flows through t-tubules.
In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell. In skeletal muslce it contributes greatly to muscle contraction.
The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction.
This Site Might Help You.
RE:
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
The T-tubules are part of the triad that interconnect the sarcoplasmic reticulum (SR). They make contact with the terminal cisternae of the SR.
Their function is to conduct the action potential throughout the muscle fiber, deeper into the muscle for contraction.
How do you think about the answers? You can sign in to vote the answer.
 What is the function of the t-tubules in a muscle contraction? | Yahoo Answers
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the_man_60
the_man_60
asked in Science & Mathematics Biology · 1 decade ago
What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? 5 Answers
Relevance
Sondra
1 decade ago
Favorite Answer
Calcium flows through t-tubules. In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell.

What is the function of the t-tubules in a muscle contraction? | Yahoo Answers
Yahoo Answers is shutting down on May 4th, 2021 (Eastern Time) and beginning April 20th, 2021 (Eastern Time) the Yahoo Answers website will be in read-only mode. There will be no changes to other Yahoo properties or services, or your Yahoo account. You can find more information about the Yahoo Answers shutdown and how to download your data on this help page. Trending News
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Real-life tragedy behind surprise Oscar nominee
Least vaccinated counties include many Trump voters
Chick-fil-A is moving in on Popeyes' key chicken turf
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One America News Network stays true to Trump
Another 'horrifying' public health issue plaguing the U.S.
As mask mandates end, 1 state bucks trend
Sikhs mourn FedEx shooting victims as questions linger
YouTube star recovering after rolling car in Wyo. 'Dirty secret' plagues women in retirement, expert warns
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Promoted
the_man_60
the_man_60
asked in Science & Mathematics Biology · 1 decade ago
What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? 5 Answers
Relevance
Sondra
1 decade ago
Favorite Answer
Calcium flows through t-tubules. In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell.

What is the function of the t-tubules in a muscle contraction? | Yahoo Answers What is the function of the t-tubules in a muscle contraction?
Trending News
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
5 Answers
Calcium flows through t-tubules.
In response to stimulation, calcium channels in t-tubules open and allow calcium to flow down it's electro-chemical gradient into the cell. In skeletal muslce it contributes greatly to muscle contraction.
The purpose of t-tubules is to allow depolarization to quickly penetrate to the interior of the cell. The t-tubules help to bring the extracellular environment to all parts of the muscle cell more quickly which better coordinates muscle contraction.
This Site Might Help You.
RE:
What is the function of the t-tubules in a muscle contraction?
What is passed through the t-tubules to allow for a muscle contraction?
The T-tubules are part of the triad that interconnect the sarcoplasmic reticulum (SR). They make contact with the terminal cisternae of the SR.
Their function is to conduct the action potential throughout the muscle fiber, deeper into the muscle for contraction.
How do you think about the answers? You can sign in to vote the answer.
 Garrott
6 years ago
This Site Might Help You. RE: What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? ...Show more
Source (s): function tubules muscle contraction: https://shortly.im/cnfo3
HulaGirl5
1 decade ago
The T-tubules are part of the triad that interconnect the sarcoplasmic reticulum (SR). They make contact with the terminal cisternae of the SR. Their function is to conduct the action potential throughout the muscle fiber, deeper into the muscle for contraction. ...Show more
doolin
Lv 4
5 years ago
T Tubules
Source (s):

Garrott
6 years ago
This Site Might Help You. RE: What is the function of the t-tubules in a muscle contraction? What is passed through the t-tubules to allow for a muscle contraction? ...Show more
Source (s): function tubules muscle contraction: https://shortly.im/cnfo3
HulaGirl5
1 decade ago
The T-tubules are part of the triad that interconnect the sarcoplasmic reticulum (SR). They make contact with the terminal cisternae of the SR. Their function is to conduct the action potential throughout the muscle fiber, deeper into the muscle for contraction. ...Show more
doolin
Lv 4
5 years ago
T Tubules
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It is the segment between 2 successive Z-Lines. What are the T tubules and what is their chief function? - T tubules are transverse tubules formed by inward extensions of the sarcolemma. -Function is to allow electrical impulses traveling along the sarcomere to move deeper into the cell. What do impulses from the T tubules do to the sarcoplasmic reticulum? - It stimulates the membranes forming the sacs of sarcoplasmic reticulum. - This stimulation causes the SR to release its stored calcium ions. What types of protein are found in thick and thin myofilaments? Where is each type of protein found? Thick myofilaments:

It is the segment between 2 successive Z-Lines. What are the T tubules and what is their chief function? - T tubules are transverse tubules formed by inward extensions of the sarcolemma. -Function is to allow electrical impulses traveling along the sarcomere to move deeper into the cell. What do impulses from the T tubules do to the sarcoplasmic reticulum? - It stimulates the membranes forming the sacs of sarcoplasmic reticulum. - This stimulation causes the SR to release its stored calcium ions. What types of protein are found in thick and thin myofilaments? Where is each type of protein found? Thick myofilaments:

T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases | Skeletal Muscle | Full Text T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
Abstract
Introduction
T-tubule plasticity
Morphological aspects of triad biogenesis
Sarcoplasmic reticulum
Transverse tubule
Molecular mechanisms involved in T-tubule biogenesis and triad formation and maintenance
Table 1 Proteins implicated in triad organization, roles and associated human diseasesa
Caveolin 3
Amphiphysin 2 (BIN1)
Dysferlin
Mitsugumins
Junctophilins
Myotubularin
The RyR-DHPR complex
Conclusion
References
Acknowledgements
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Corresponding author
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Authors’ original file for figure 3
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 T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases | Skeletal Muscle | Full Text
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Published: 13 July 2011
T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
Lama Al-Qusairi
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Jocelyn Laporte
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Skeletal Muscle
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Abstract
In skeletal muscle, the excitation-contraction (EC) coupling machinery mediates the translation of the action potential transmitted by the nerve into intracellular calcium release and muscle contraction. EC coupling requires a highly specialized membranous structure, the triad, composed of a central T-tubule surrounded by two terminal cisternae from the sarcoplasmic reticulum. While several proteins located on these structures have been identified, mechanisms governing T-tubule biogenesis and triad formation remain largely unknown. Here, we provide a description of triad structure and plasticity and review the role of proteins that have been linked to T-tubule biogenesis and triad formation and/or maintenance specifically in skeletal muscle: caveolin 3, amphiphysin 2, dysferlin, mitsugumins, junctophilins, myotubularin, ryanodine receptor, and dihydhropyridine Receptor. The importance of these proteins in triad biogenesis and subsequently in muscle contraction is sustained by studies on animal models and by the direct implication of most of these proteins in human myopathies. Introduction
To trigger skeletal muscle contraction, the action potential generated by motor neurons is transmitted through motor nerves to muscle cells. The excitation-contraction (EC) coupling, i.e. signal transmission from the sarcolemma to the actin/myosin apparatus, is mediated by a second messenger, calcium ions.

T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases | Skeletal Muscle | Full Text

T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
Abstract
Introduction
T-tubule plasticity
Morphological aspects of triad biogenesis
Sarcoplasmic reticulum
Transverse tubule
Molecular mechanisms involved in T-tubule biogenesis and triad formation and maintenance
Table 1 Proteins implicated in triad organization, roles and associated human diseasesa
Caveolin 3
Amphiphysin 2 (BIN1)
Dysferlin
Mitsugumins
Junctophilins
Myotubularin
The RyR-DHPR complex
Conclusion
References
Acknowledgements
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T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
Lama Al-Qusairi
1, 2, 3, 4, 5, 6
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Jocelyn Laporte
1, 2, 3, 4, 5
Skeletal Muscle
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Abstract
In skeletal muscle, the excitation-contraction (EC) coupling machinery mediates the translation of the action potential transmitted by the nerve into intracellular calcium release and muscle contraction. EC coupling requires a highly specialized membranous structure, the triad, composed of a central T-tubule surrounded by two terminal cisternae from the sarcoplasmic reticulum. While several proteins located on these structures have been identified, mechanisms governing T-tubule biogenesis and triad formation remain largely unknown. Here, we provide a description of triad structure and plasticity and review the role of proteins that have been linked to T-tubule biogenesis and triad formation and/or maintenance specifically in skeletal muscle: caveolin 3, amphiphysin 2, dysferlin, mitsugumins, junctophilins, myotubularin, ryanodine receptor, and dihydhropyridine Receptor. The importance of these proteins in triad biogenesis and subsequently in muscle contraction is sustained by studies on animal models and by the direct implication of most of these proteins in human myopathies. Introduction
To trigger skeletal muscle contraction, the action potential generated by motor neurons is transmitted through motor nerves to muscle cells. The excitation-contraction (EC) coupling, i.e. signal transmission from the sarcolemma to the actin/myosin apparatus, is mediated by a second messenger, calcium ions.

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 T-tubule - Wikipedia
T-tubule
From Wikipedia, the free encyclopedia
(Redirected from T-tubules)
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Invagination of the plasma membrane of a muscle cell that extends inward from the cell surface around each myofibril; the ends of T-tubules make contact with the sarcoplasmic reticulum membrane
T-tubule
Skeletal muscle, with T-tubule labelled in zoomed in image. T-tubule structure and relationship to the sarcoplasmic reticulum in skeletal muscle
Details
Part of
Cell membrane of Skeletal muscle and cardiac muscle cells. Identifiers
Latin
tubulus transversus
TH
H2.00.05.2.01018, H2.00.05.2.02013
Anatomical terminology
T-tubules ( transverse tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells. With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. T-tubule structure may be affected by disease, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1 Structure
1.1 Regulators
2 Function
2.1 Excitation-contraction coupling
2.2 Calcium control
2.3 Detubulation
3 History
4 Clinical significance
5 See also
6 References
Structure
T-tubules are tubules formed from the same phospholipid bilayer as the surface membrane or sarcolemma of skeletal or cardiac muscle cells. They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma.

T-tubule - Wikipedia

T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 T-tubule - Wikipedia
T-tubule
From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Invagination of the plasma membrane of a muscle cell that extends inward from the cell surface around each myofibril; the ends of T-tubules make contact with the sarcoplasmic reticulum membrane
T-tubule
Skeletal muscle, with T-tubule labelled in zoomed in image. T-tubule structure and relationship to the sarcoplasmic reticulum in skeletal muscle
Details
Part of
Cell membrane of skeletal muscle and cardiac muscle cells. Identifiers
Latin
tubulus transversus
TH
H2.00.05.2.01018, H2.00.05.2.02013
Anatomical terminology
T-tubules ( transverse tubules) are extensions of the cell membrane that penetrate into the centre of skeletal and cardiac muscle cells. With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration. Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. T-tubule structure and function are affected beat-by-beat by cardiomyocyte contraction, as well as by diseases, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1 Structure
1.1 Regulators
2 Function
2.1 Excitation-contraction coupling
2.2 Calcium control
2.3 Detubulation
3 History
4 Clinical significance
5 See also
6 References
Structure
T-tubules are tubules formed from the same phospholipid bilayer as the surface membrane or sarcolemma of skeletal or cardiac muscle cells. They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma.

T-tubule - Wikipedia

Transverse Tubular System - an overview | ScienceDirect Topics Transverse Tubular System
Transverse Tubular System
Cardiovascular Physiology
Transverse Tubules
Ion Channel Trafficking
T-Tubules
Functional Organization of Vertebrate Plasma Membrane
2.4 T-tubules, physiology, and disease
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Cardiac Rhythm
4.2.1 Ca++ Regulation
Cardiovascular Physiology
Membrane Depolarization and Activator Calcium
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Ion Channel Trafficking in the Heart
Ca V 1.2 Channel Trafficking in the Heart
Ca V 1.2 Forward Trafficking in Normal Heart Physiology
Ca V 1.2 Forward Trafficking in Heart Pathophysiology
Accessory Proteins Involved in Ca V 1.2 Targeted Delivery
T-Tubules and Ca V 1.2 Regulation in Normal Heart Physiology
T-Tubules and Ca V 1.2 Regulation in Heart Pathophysiology
Ca V 1.2 Internalization
Muscles
Coupling Action Potentials to Contraction
Skeletal Muscle Excitability
AIII Further Evidence that the T-Tubules Fire Na + -Dependent AP s
 Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads. 71 Integrity of NCX/NKA/InsP3 complex is critical in removing calcium from the clefts between T-tubule surface and SR membrane, facilitating calcium decline during relaxation. Therefore, intracellular calcium equilibrium can be achieved by balancing calcium entry through LTCC clustered at BIN1-membrane and calcium removal by NCX anchored at ankyrin B-induced membrane. View chapter Purchase book
Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780128020029000029
Functional Organization of Vertebrate Plasma Membrane
Crystal F. Kline, Peter J. Mohler, in Current Topics in Membranes, 2013
2.4 T-tubules, physiology, and disease
T-tubule structure and function is severely compromised in human heart failure and in small and large animal models of cardiovascular disease ( Balijepalli et al., 2003; Louch et al., 2004 ). Animal models of heart failure exhibit T-tubule disorganization that appears to result from various myocardial insults, including sustained tachycardia ( Balijepalli et al.,

Transverse Tubular System - an overview | ScienceDirect Topics

Transverse Tubular System
Transverse Tubular System
Cardiovascular Physiology
Transverse Tubules
Ion Channel Trafficking
T-Tubules
Functional Organization of Vertebrate Plasma Membrane
2.4 T-tubules, physiology, and disease
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Cardiac Rhythm
4.2.1 Ca++ Regulation
Cardiovascular Physiology
Membrane Depolarization and Activator Calcium
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Ion Channel Trafficking in the Heart
Ca V 1.2 Channel Trafficking in the Heart
Ca V 1.2 Forward Trafficking in Normal Heart Physiology
Ca V 1.2 Forward Trafficking in Heart Pathophysiology
Accessory Proteins Involved in Ca V 1.2 Targeted Delivery
T-Tubules and Ca V 1.2 Regulation in Normal Heart Physiology
T-Tubules and Ca V 1.2 Regulation in Heart Pathophysiology
Ca V 1.2 Internalization
Muscles
Coupling Action Potentials to Contraction
Skeletal Muscle Excitability
AIII Further Evidence that the T-Tubules Fire Na + -Dependent AP s

Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads. 71 Integrity of NCX/NKA/InsP3 complex is critical in removing calcium from the clefts between T-tubule surface and SR membrane, facilitating calcium decline during relaxation. Therefore, intracellular calcium equilibrium can be achieved by balancing calcium entry through LTCC clustered at BIN1-membrane and calcium removal by NCX anchored at ankyrin B-induced membrane. View chapter Purchase book
Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780128020029000029
Functional Organization of Vertebrate Plasma Membrane
Crystal F. Kline, Peter J. Mohler, in Current Topics in Membranes, 2013
2.4 T-tubules, physiology, and disease
T-tubule structure and function is severely compromised in human heart failure and in small and large animal models of cardiovascular disease ( Balijepalli et al., 2003; Louch et al., 2004 ). Animal models of heart failure exhibit T-tubule disorganization that appears to result from various myocardial insults, including sustained tachycardia ( Balijepalli et al.,

T-tubule | Psychology Wiki | Fandom T-tubule
T-tubule
Contents
Structure
Excitation-contraction coupling
Detubulation
See also
External links
 T-tubule | Psychology Wiki | Fandom
T-tubule
T-tubule
[ [Image:|190px|center|]]

Latin
tubulus transversus
Gray's
subject #
System

MeSH
[1]
[ [Image:|190px|center|]]

A T-tubule (or transverse tubule) is a deep invagination of the sarcolemma, which is the plasma membrane, only found in skeletal and cardiac muscle cells. These invaginations allow depolarization of the membrane to quickly penetrate to the interior of the cell. Contents
1
Structure
2
Excitation-contraction coupling
3
Detubulation
4
See also
5
External links
Structure
Each muscle fiber is surrounded by a sarcolemma (the muscle fiber's plasma membrane) which invaginates perpendicular to the length of the fiber to form what is called a T-tubule. At these invaginations the sarcolemma is studded with a large number of L-type calcium channels. In skeletal muscle cells specifically, T-tubule invaginations are typically located at the junction overlap between the A and I bands of the sarcomere, and together with a pair of terminal cisternae (bulbous enlarged areas of the sarcoplasmic reticulum) it forms an arrangement called a triad. Cardiac muscle has a similar structure; instead of a triad there is a diad, which is composed of a T-tubule and a single terminal cisterna, and it occurs at the Z line. It is physiologically important for excitation-contraction coupling (see section below) that the T-tubules are positioned close to the terminal cisternae of the sarcoplasmic reticulum as the triad or diad arrangement allows physical and functional contact by voltage dependent L-type calcium channels. So, an action potential along the sarcolemma causes calcium channels to open in the terminal cisternae / sarcoplasmic reticulum which enables calcium to move from the sarcoplasmic reticulum into cytoplasm and the intracellular calcium concentration to increase. Excitation-contraction coupling
See Excitation-contraction coupling
T-tubules are the major sites for the coupling of excitation and contraction, which is the process whereby the spreading depolarization is converted into force production by muscle fibers.

T-tubule | Psychology Wiki | Fandom

T-tubule
T-tubule
Contents
Structure
Excitation-contraction coupling
Detubulation
See also
External links

T-Tubule - an overview | ScienceDirect Topics T-Tubule
T-Tubule
Ion Channel Trafficking
T-Tubules
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Muscles
Coupling Action Potentials to Contraction
The Cellular Basis of Cardiac Contractility
The SR Releases Stored Ca 2+ to Activate Contraction
Disorders of Muscle Excitability
Calcium couples muscle membrane excitation to filament contraction
Muscle physiology
Excitation–contraction coupling
EXERCISE | Muscle
Voltage-dependent Sarcoplasmic Reticulum Ca 2+ Release
 T-Tubule - an overview | ScienceDirect Topics
T-Tubule
T tubules extend from the free surface throughout the cells in a generally transverse direction, coursing around the myofibrils at the levels of the Z bands. From: Haschek and Rousseaux's Handbook of Toxicologic Pathology (Third Edition), 2013
Download as PDF
About this page
Ion Channel Trafficking
T.T. Hong, R.M. Shaw, in Ion Channels in Health and Disease, 2016
T-Tubules
T-tubule membrane is associated with a unique set of ion channels supported by membrane structural subdomains.23 Immunocytochemistry and patch clamp data indicate that 80% of the sarcolemma LTCCs are concentrated at T-tubules. Localization of LTCCs to T-tubules is critical in bringing LTCCs to the vicinity of calcium sense and release channel RyR at SR membrane. Approximation of LTCCs and RyRs form a functional microdomain, the cardiac dyads, which are the individual calcium-releasing units in cardiomyocytes. As discussed earlier, Targeted Delivery also applies to Cav1.2 channel localization to T-tubule surface, which requires a membrane scaffolding protein BIN1. 26 Interestingly, BIN1 also forms minifolds within T-tubules, affecting extracellular ion diffusion thereby controlling the driving force of Cav1.2 channel activity. 6 BIN1-folded subdomains within T-tubules may also limit LTCC lateral diffusion once the channels are inserted into T-tubule membrane, to maintain functional LTCC-RyR dyads. Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads.

T-Tubule - an overview | ScienceDirect Topics

T-Tubule
T-Tubule
Ion Channel Trafficking
T-Tubules
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Muscles
Coupling Action Potentials to Contraction
The Cellular Basis of Cardiac Contractility
The SR Releases Stored Ca 2+ to Activate Contraction
Disorders of Muscle Excitability
Calcium couples muscle membrane excitation to filament contraction
Muscle physiology
Excitation–contraction coupling
EXERCISE | Muscle
Voltage-dependent Sarcoplasmic Reticulum Ca 2+ Release

T-Tubule - an overview | ScienceDirect Topics
T-Tubule
T tubules extend from the free surface throughout the cells in a generally transverse direction, coursing around the myofibrils at the levels of the Z bands. From: Haschek and Rousseaux's Handbook of Toxicologic Pathology (Third Edition), 2013
Download as PDF
About this page
Ion Channel Trafficking
T.T. Hong, R.M. Shaw, in Ion Channels in Health and Disease, 2016
T-Tubules
T-tubule membrane is associated with a unique set of ion channels supported by membrane structural subdomains.23 Immunocytochemistry and patch clamp data indicate that 80% of the sarcolemma LTCCs are concentrated at T-tubules. Localization of LTCCs to T-tubules is critical in bringing LTCCs to the vicinity of calcium sense and release channel RyR at SR membrane. Approximation of LTCCs and RyRs form a functional microdomain, the cardiac dyads, which are the individual calcium-releasing units in cardiomyocytes. As discussed earlier, Targeted Delivery also applies to Cav1.2 channel localization to T-tubule surface, which requires a membrane scaffolding protein BIN1. 26 Interestingly, BIN1 also forms minifolds within T-tubules, affecting extracellular ion diffusion thereby controlling the driving force of Cav1.2 channel activity. 6 BIN1-folded subdomains within T-tubules may also limit LTCC lateral diffusion once the channels are inserted into T-tubule membrane, to maintain functional LTCC-RyR dyads. Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 Once formed, the ability of the tubular system to maintain its remarkable degree of structure despite the forces exerted during the normal contraction cycle may be due to the presence of a “scaffold” of focal adhesion molecules, membrane-associated proteins, and basal lamina proteins. 20
Proteins Present in the T-Tubule Membrane
The function of the t-tubules depends not only on their structure but also on the proteins within, and adjacent to, the t-tubule membrane. Immunohistochemical techniques have been widely used to investigate the location of proteins within cardiac ventricular myocytes. Such studies have shown marked variations in the distribution of membrane proteins, although a distinction needs to be drawn between the fraction of a particular type of protein located at the t-tubule and whether this is greater than the fraction of the total cell membrane located within the t-tubules, ie, whether protein density is higher (concentrated) at the t-tubule. This is discussed further in Interpretation of Immunohistochemical Data and in Conclusions and Unanswered Questions. Ca2+-Handling Proteins
The location of sarcolemmal Ca 2+ -handling proteins is important because of their role in excitation-contraction coupling and because the Ca 2+ -release channels (ryanodine receptors [RyRs]) of the sarcoplasmic reticulum (SR) are concentrated close to the t-tubule (see Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules). In the rabbit heart, an early study showed that a membrane fraction from the t-tubules had a higher density of L-type Ca 2+ channels than did membrane from the surface sarcolemma. 21 A more recent immunologic study also found this channel to be concentrated in the t-tubules of adult rabbit ventricular myocytes, with less staining of the surface sarcolemma, although the surface staining that did occur was punctate and associated with junctional SR. 22 In rat heart, the L-type Ca 2+ channel, and hence current ( ICa ), is also concentrated in the t-tubules, with estimates ranging from 3 to 9 times more concentrated in the t-tubule membrane than on the surface sarcolemma. 23–26 Comparative studies suggest that the t-tubular concentration of the L-type Ca 2+ channel is greater in rat ventricular myocytes than in those from the rabbit.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 We will also consider the possible role of the t-tubules in the functional changes that occur during cardiac development, hypertrophy, and failure. Occurrence and Morphology of the T-Tubules
T-tubules are present in the cardiac tissue of all species of mammals so far investigated (eg, mice, 1 rats, 2 guinea pigs, 3 rabbits, 4 dogs, 5 pigs, 1 and humans 6) but appear to be absent in avian, 7 reptile 8 and amphibian 8 cardiac tissue. Within mammalian cardiac tissue, t-tubules occur predominantly in ventricular myocytes, being either absent or far less developed in atrial, pacemaking, and conducting tissue, 9 although a recent report has suggested that ≈50% of atrial myocytes possess a sparse irregular tubular system. 10 The following discussion will concentrate on mammalian ventricular myocytes. The t-tubules are invaginations of the sarcolemma and glycocalyx, which appears to remain associated with the sarcolemma within the t-tubules. 11 Early studies of cardiac muscle showed that they occur at the Z line, at the end of each sarcomere 12; therefore, they occur at intervals of ≈2 μm along the longitudinal axis of the ventricular myocyte. Subsequent studies have shown that the t-tubular system also has longitudinal extensions. 13 Although the t-tubules leave the surface membrane at the Z line, forming an approximately rectangular array, only ≈60% of the tubular volume occurs near the Z line; the other 40% occurs between the Z lines.

We will also consider the possible role of the t-tubules in the functional changes that occur during cardiac development, hypertrophy, and failure. Occurrence and Morphology of the T-Tubules
T-tubules are present in the cardiac tissue of all species of mammals so far investigated (eg, mice, 1 rats, 2 guinea pigs, 3 rabbits, 4 dogs, 5 pigs, 1 and humans 6) but appear to be absent in avian, 7 reptile 8 and amphibian 8 cardiac tissue. Within mammalian cardiac tissue, t-tubules occur predominantly in ventricular myocytes, being either absent or far less developed in atrial, pacemaking, and conducting tissue, 9 although a recent report has suggested that ≈50% of atrial myocytes possess a sparse irregular tubular system. 10 The following discussion will concentrate on mammalian ventricular myocytes. The t-tubules are invaginations of the sarcolemma and glycocalyx, which appears to remain associated with the sarcolemma within the t-tubules. 11 Early studies of cardiac muscle showed that they occur at the Z line, at the end of each sarcomere 12; therefore, they occur at intervals of ≈2 μm along the longitudinal axis of the ventricular myocyte. Subsequent studies have shown that the t-tubular system also has longitudinal extensions. 13 Although the t-tubules leave the surface membrane at the Z line, forming an approximately rectangular array, only ≈60% of the tubular volume occurs near the Z line; the other 40% occurs between the Z lines.

Chapter 9 Mastering A&P Flashcards | Quizlet Chapter 9 Mastering A&P
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Key concepts:
Terms in this set (40)
 As the action potential spreads down the T tubules of the triads, voltage-sensitive tubule proteins change shape. How does the shape change of these proteins lead to contraction? It allows calcium to exit the sarcoplasmic reticulum and enter the cytosol. Which selection correctly describes the role of calcium in coupling? Calcium binds to troponin, which moves tropomyosin and exposes the myosin-binding sites on actin. Which selection best describes the initial event in contraction? Myosin heads bind to the newly exposed myosin-binding sites on actin to form cross bridges
cistern
swollen chamber of an organelle that lies on either side of the T-tubules
voltage-sensitive tubule proteins
a protein that changes shape as a direct result of an action potential
T tubules
a structure that forms a path from the membrane to cells interior
Troponin
protein that binds calcium
excitation-contraction coupling to the correct order
1. An action potential is generated
at the sarcolemma. 2. Action potential goes down the T tubule.

Chapter 9 Mastering A&P Flashcards | Quizlet

Chapter 9 Mastering A&P
Chapter 9 Mastering A&P
PLAY
Key concepts:
Terms in this set (40)

As the action potential spreads down the T tubules of the triads, voltage-sensitive tubule proteins change shape. How does the shape change of these proteins lead to contraction? It allows calcium to exit the sarcoplasmic reticulum and enter the cytosol. Which selection correctly describes the role of calcium in coupling? Calcium binds to troponin, which moves tropomyosin and exposes the myosin-binding sites on actin. Which selection best describes the initial event in contraction? Myosin heads bind to the newly exposed myosin-binding sites on actin to form cross bridges
cistern
swollen chamber of an organelle that lies on either side of the T-tubules
voltage-sensitive tubule proteins
a protein that changes shape as a direct result of an action potential
T tubules
a structure that forms a path from the membrane to cells interior
Troponin
protein that binds calcium
excitation-contraction coupling to the correct order
1. An action potential is generated
at the sarcolemma. 2. Action potential goes down the T tubule.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 Ca2+-Handling Proteins
The location of sarcolemmal Ca 2+ -handling proteins is important because of their role in excitation-contraction coupling and because the Ca 2+ -release channels (ryanodine receptors [RyRs]) of the sarcoplasmic reticulum (SR) are concentrated close to the t-tubule (see Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules). In the rabbit heart, an early study showed that a membrane fraction from the t-tubules had a higher density of L-type Ca 2+ channels than did membrane from the surface sarcolemma. 21 A more recent immunologic study also found this channel to be concentrated in the t-tubules of adult rabbit ventricular myocytes, with less staining of the surface sarcolemma, although the surface staining that did occur was punctate and associated with junctional SR. 22 In rat heart, the L-type Ca 2+ channel, and hence current ( ICa ), is also concentrated in the t-tubules, with estimates ranging from 3 to 9 times more concentrated in the t-tubule membrane than on the surface sarcolemma. 23–26 Comparative studies suggest that the t-tubular concentration of the L-type Ca 2+ channel is greater in rat ventricular myocytes than in those from the rabbit. 22
Although a high density of L-type Ca 2+ channel at the Z line has been reported in all studies of which we are aware, it has also been reported tha

Ca2+-Handling Proteins
The location of sarcolemmal Ca 2+ -handling proteins is important because of their role in excitation-contraction coupling and because the Ca 2+ -release channels (ryanodine receptors [RyRs]) of the sarcoplasmic reticulum (SR) are concentrated close to the t-tubule (see Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules). In the rabbit heart, an early study showed that a membrane fraction from the t-tubules had a higher density of L-type Ca 2+ channels than did membrane from the surface sarcolemma. 21 A more recent immunologic study also found this channel to be concentrated in the t-tubules of adult rabbit ventricular myocytes, with less staining of the surface sarcolemma, although the surface staining that did occur was punctate and associated with junctional SR. 22 In rat heart, the L-type Ca 2+ channel, and hence current ( ICa ), is also concentrated in the t-tubules, with estimates ranging from 3 to 9 times more concentrated in the t-tubule membrane than on the surface sarcolemma. 23–26 Comparative studies suggest that the t-tubular concentration of the L-type Ca 2+ channel is greater in rat ventricular myocytes than in those from the rabbit. 22
Although a high density of L-type Ca 2+ channel at the Z line has been reported in all studies of which we are aware, it has also been reported tha

T-Tubule - an overview | ScienceDirect Topics T-Tubule
T-Tubule
Ion Channel Trafficking
T-Tubules
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Muscles
Coupling Action Potentials to Contraction
The Cellular Basis of Cardiac Contractility
The SR Releases Stored Ca 2+ to Activate Contraction
Disorders of Muscle Excitability
Calcium couples muscle membrane excitation to filament contraction
Muscle physiology
Excitation–contraction coupling
EXERCISE | Muscle
Voltage-dependent Sarcoplasmic Reticulum Ca 2+ Release
 As discussed earlier, Targeted Delivery also applies to Cav1.2 channel localization to T-tubule surface, which requires a membrane scaffolding protein BIN1. 26 Interestingly, BIN1 also forms minifolds within T-tubules, affecting extracellular ion diffusion thereby controlling the driving force of Cav1.2 channel activity. 6 BIN1-folded subdomains within T-tubules may also limit LTCC lateral diffusion once the channels are inserted into T-tubule membrane, to maintain functional LTCC-RyR dyads. Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads. 71 Integrity of NCX/NKA/InsP3 complex is critical in removing calcium from the clefts between T-tubule surface and SR membrane, facilitating calcium decline during relaxation. Therefore, intracellular calcium equilibrium can be achieved by balancing calcium entry through LTCC clustered at BIN1-membrane and calcium removal by NCX anchored at ankyrin B-induced membrane. View chapter Purchase book
Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780128020029000029
Skeletal Muscle
Clara Franzini-Armstrong, Andrew G. Engel, in Muscle, 2012
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
T-tubules have a random, mostly longitudinal, disposition between the myofibrils during their initial formation but even at this stage they immediately form junctions with SR elements.

As discussed earlier, Targeted Delivery also applies to Cav1.2 channel localization to T-tubule surface, which requires a membrane scaffolding protein BIN1. 26 Interestingly, BIN1 also forms minifolds within T-tubules, affecting extracellular ion diffusion thereby controlling the driving force of Cav1.2 channel activity. 6 BIN1-folded subdomains within T-tubules may also limit LTCC lateral diffusion once the channels are inserted into T-tubule membrane, to maintain functional LTCC-RyR dyads. Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads. 71 Integrity of NCX/NKA/InsP3 complex is critical in removing calcium from the clefts between T-tubule surface and SR membrane, facilitating calcium decline during relaxation. Therefore, intracellular calcium equilibrium can be achieved by balancing calcium entry through LTCC clustered at BIN1-membrane and calcium removal by NCX anchored at ankyrin B-induced membrane. View chapter Purchase book
Read full chapter
URL: https://www.sciencedirect.com/science/article/pii/B9780128020029000029
Skeletal Muscle
Clara Franzini-Armstrong, Andrew G. Engel, in Muscle, 2012
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
T-tubules have a random, mostly longitudinal, disposition between the myofibrils during their initial formation but even at this stage they immediately form junctions with SR elements.

10.3 Muscle Fiber Excitation, Contraction, and Relaxation – Anatomy & Physiology 10.3 Muscle Fiber Excitation, Contraction, and Relaxation
10.3 Muscle Fiber Excitation, Contraction, and Relaxation
Learning Objectives
The Neuromuscular Junction
External Website
Excitation-Contraction Coupling
Contraction and Relaxation
External Website
Cross-Bridge Cycling
Sources of ATP
Relaxation of a Skeletal Muscle
Muscle Strength
Interactive Link Questions
Review Questions
Critical Thinking Questions
Glossary
Solutions
 A cross-bridge forms between actin and the myosin heads triggering contraction. As long as Ca ++ ions remain in the sarcoplasm to bind to troponin, and as long as ATP is available, the muscle fiber will continue to shorten. Relaxation of a Muscle Fiber: Ca ++ ions are pumped back into the SR, which causes the tropomyosin to reshield the binding sites on the actin strands. A muscle may also stop contracting when it runs out of ATP and becomes fatigued. Muscle contraction usually stops when signaling from the motor neuron ends, which repolarizes the sarcolemma and T-tubules, and closes the calcium channels in the SR. Ca ++ ions are then pumped back into the SR, which causes the tropomyosin to re-cover the binding sites on actin ( Figure 10.3.2 ). External Website
The release of calcium ions initiates muscle contractions. Watch this video to learn more about the role of calcium. ( a) What are “T-tubules” and what is their role? (

10.3 Muscle Fiber Excitation, Contraction, and Relaxation – Anatomy & Physiology

10.3 Muscle Fiber Excitation, Contraction, and Relaxation
10.3 Muscle Fiber Excitation, Contraction, and Relaxation
Learning Objectives
The Neuromuscular Junction
External Website
Excitation-Contraction Coupling
Contraction and Relaxation
External Website
Cross-Bridge Cycling
Sources of ATP
Relaxation of a Skeletal Muscle
Muscle Strength
Interactive Link Questions
Review Questions
Critical Thinking Questions
Glossary
Solutions

A cross-bridge forms between actin and the myosin heads triggering contraction. As long as Ca ++ ions remain in the sarcoplasm to bind to troponin, and as long as ATP is available, the muscle fiber will continue to shorten. Relaxation of a Muscle Fiber: Ca ++ ions are pumped back into the SR, which causes the tropomyosin to reshield the binding sites on the actin strands. A muscle may also stop contracting when it runs out of ATP and becomes fatigued. Muscle contraction usually stops when signaling from the motor neuron ends, which repolarizes the sarcolemma and T-tubules, and closes the calcium channels in the SR. Ca ++ ions are then pumped back into the SR, which causes the tropomyosin to re-cover the binding sites on actin ( Figure 10.3.2 ). External Website
The release of calcium ions initiates muscle contractions. Watch this video to learn more about the role of calcium. ( a) What are “T-tubules” and what is their role? (

Cardiac excitation-contraction coupling - Osmosis Cardiac excitation-contraction coupling
Cardiac excitation-contraction coupling
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Jessica Moore
Cardiovascular system
Auscultation of the heart
Electrocardiography
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Cardiac excitation-contraction coupling
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High Yield Notes
Flashcards
Cardiac excitation-contraction coupling
Transcript
 Another feature of cardiomyocytes are passageways called transverse tubules, or T-tubules. T-tubules are extensions of the outside environment. They increase the surface area of the cardiomyocyte and they look like the letter T, so it’s easy to remember their name. Think of a large walk-through aquarium: you can walk through tunnels and look at the sea creatures all around you, but you’re not in the water with them. Finally, there’s the sarcoplasmic reticulum, which is an organelle that stores intracellular calcium, the calcium that is sequestered inside the cell. When a depolarization wavefront hits a cardiomyocyte, a few calcium ions flow through gap junctions, and if a threshold membrane potential is reached, then sodium channels start to open up. If there’s a depolarization, then ions start to move across the cell membrane, and that’s where the T-tubules play a key role. During the part of the cardiomyocyte action potential when calcium ions flow into the cell, the presence of T-tubules helps bring calcium deep into the cell. Once this extracellular calcium gets inside, it binds to the ryanodine receptors on the sarcoplasmic reticulum, which releases even more calcium into the cell - a process called calcium-induced calcium release.

Cardiac excitation-contraction coupling - Osmosis

Cardiac excitation-contraction coupling
Cardiac excitation-contraction coupling
Continue learning with us!
Jessica Moore
Cardiovascular system
Auscultation of the heart
Electrocardiography
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Cardiac excitation-contraction coupling
Flashcards
High Yield Notes
Flashcards
Cardiac excitation-contraction coupling
Transcript

Another feature of cardiomyocytes are passageways called transverse tubules, or T-tubules. T-tubules are extensions of the outside environment. They increase the surface area of the cardiomyocyte and they look like the letter T, so it’s easy to remember their name. Think of a large walk-through aquarium: you can walk through tunnels and look at the sea creatures all around you, but you’re not in the water with them. Finally, there’s the sarcoplasmic reticulum, which is an organelle that stores intracellular calcium, the calcium that is sequestered inside the cell. When a depolarization wavefront hits a cardiomyocyte, a few calcium ions flow through gap junctions, and if a threshold membrane potential is reached, then sodium channels start to open up. If there’s a depolarization, then ions start to move across the cell membrane, and that’s where the T-tubules play a key role. During the part of the cardiomyocyte action potential when calcium ions flow into the cell, the presence of T-tubules helps bring calcium deep into the cell. Once this extracellular calcium gets inside, it binds to the ryanodine receptors on the sarcoplasmic reticulum, which releases even more calcium into the cell - a process called calcium-induced calcium release.

Transverse Tubular System - an overview | ScienceDirect Topics Transverse Tubular System
Transverse Tubular System
Cardiovascular Physiology
Transverse Tubules
Ion Channel Trafficking
T-Tubules
Functional Organization of Vertebrate Plasma Membrane
2.4 T-tubules, physiology, and disease
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Cardiac Rhythm
4.2.1 Ca++ Regulation
Cardiovascular Physiology
Membrane Depolarization and Activator Calcium
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Ion Channel Trafficking in the Heart
Ca V 1.2 Channel Trafficking in the Heart
Ca V 1.2 Forward Trafficking in Normal Heart Physiology
Ca V 1.2 Forward Trafficking in Heart Pathophysiology
Accessory Proteins Involved in Ca V 1.2 Targeted Delivery
T-Tubules and Ca V 1.2 Regulation in Normal Heart Physiology
T-Tubules and Ca V 1.2 Regulation in Heart Pathophysiology
Ca V 1.2 Internalization
Muscles
Coupling Action Potentials to Contraction
Skeletal Muscle Excitability
AIII Further Evidence that the T-Tubules Fire Na + -Dependent AP s
 Localization of LTCCs to T-tubules is critical in bringing LTCCs to the vicinity of calcium sense and release channel RyR at SR membrane. Approximation of LTCCs and RyRs form a functional microdomain, the cardiac dyads, which are the individual calcium-releasing units in cardiomyocytes. As discussed earlier, Targeted Delivery also applies to Cav1.2 channel localization to T-tubule surface, which requires a membrane scaffolding protein BIN1. 26 Interestingly, BIN1 also forms minifolds within T-tubules, affecting extracellular ion diffusion thereby controlling the driving force of Cav1.2 channel activity. 6 BIN1-folded subdomains within T-tubules may also limit LTCC lateral diffusion once the channels are inserted into T-tubule membrane, to maintain functional LTCC-RyR dyads. Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads. 71 Integrity of NCX/NKA/InsP3 complex is critical in removing calcium from the clefts between T-tubule surface and SR membrane, facilitating calcium decline during relaxation. Therefore, intracellular calcium equilibrium can be achieved by balancing calcium entry through LTCC clustered at BIN1-membrane and calcium removal by NCX anchored at ankyrin B-induced membrane. View chapter Purchase book
Read full chapter
URL:

Localization of LTCCs to T-tubules is critical in bringing LTCCs to the vicinity of calcium sense and release channel RyR at SR membrane. Approximation of LTCCs and RyRs form a functional microdomain, the cardiac dyads, which are the individual calcium-releasing units in cardiomyocytes. As discussed earlier, Targeted Delivery also applies to Cav1.2 channel localization to T-tubule surface, which requires a membrane scaffolding protein BIN1. 26 Interestingly, BIN1 also forms minifolds within T-tubules, affecting extracellular ion diffusion thereby controlling the driving force of Cav1.2 channel activity. 6 BIN1-folded subdomains within T-tubules may also limit LTCC lateral diffusion once the channels are inserted into T-tubule membrane, to maintain functional LTCC-RyR dyads. Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads. 71 Integrity of NCX/NKA/InsP3 complex is critical in removing calcium from the clefts between T-tubule surface and SR membrane, facilitating calcium decline during relaxation. Therefore, intracellular calcium equilibrium can be achieved by balancing calcium entry through LTCC clustered at BIN1-membrane and calcium removal by NCX anchored at ankyrin B-induced membrane. View chapter Purchase book
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URL:

WEEK 13 - Male reproductive system (Module 11) Flashcards | Quizlet WEEK 13 - Male reproductive system (Module 11)
WEEK 13 - Male reproductive system (Module 11)
Terms in this set (28)
 is a glycoprotein (beta-globulin) produced by the Sertoli cells in the seminiferous tubules of the testis that binds specifically to testosterone & dihydrotestosterone (DHT). The higher levels of these hormones enable spermatogenesis in the seminiferous tubules and sperm maturation in the epididymis
11.22. Discuss the role of the hormone Inhibin in the feedback process, what cell secretes it and why, what are its target cells? ...
11.23. Describe testosterone in terms of its chemical makeup (ie is it amino acid, protein or steroid) and how this affects its method of transport in the blood and method of action on target cells. a steroid hormone from the androgen group
Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (DHT), DHT binds to the same androgen receptor even more strongly than testosterone, so that its androgenic potency is about 5 times that of T. T-receptor or DHT-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects. 11.24. Testosterone is an important hormone in the male reproductive system, discuss the effects of this hormone in relation to the seminiferous tubule and the whole body? ...
;

WEEK 13 - Male reproductive system (Module 11) Flashcards | Quizlet

WEEK 13 - Male reproductive system (Module 11)
WEEK 13 - Male reproductive system (Module 11)
Terms in this set (28)

is a glycoprotein (beta-globulin) produced by the Sertoli cells in the seminiferous tubules of the testis that binds specifically to testosterone & dihydrotestosterone (DHT). The higher levels of these hormones enable spermatogenesis in the seminiferous tubules and sperm maturation in the epididymis
11.22. Discuss the role of the hormone Inhibin in the feedback process, what cell secretes it and why, what are its target cells? ...
11.23. Describe testosterone in terms of its chemical makeup (ie is it amino acid, protein or steroid) and how this affects its method of transport in the blood and method of action on target cells. a steroid hormone from the androgen group
Free testosterone (T) is transported into the cytoplasm of target tissue cells, where it can bind to the androgen receptor, or can be reduced to 5α-dihydrotestosterone (DHT), DHT binds to the same androgen receptor even more strongly than testosterone, so that its androgenic potency is about 5 times that of T. T-receptor or DHT-receptor complex undergoes a structural change that allows it to move into the cell nucleus and bind directly to specific nucleotide sequences of the chromosomal DNA. The areas of binding are called hormone response elements (HREs), and influence transcriptional activity of certain genes, producing the androgen effects. 11.24. Testosterone is an important hormone in the male reproductive system, discuss the effects of this hormone in relation to the seminiferous tubule and the whole body? ...
;

Mastering A&P Chapter 9 - Muscle and Muscle Tissue Diagram | Quizlet Mastering A&P Chapter 9 - Muscle and Muscle Tissue
Mastering A&P Chapter 9 - Muscle and Muscle Tissue
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Terms in this set (104)
 When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? motor endplates
terminal cisternae
sarcoplasmic reticulum
transverse or T tubules
Transverse or T tubules
T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. Action potentials. Acetylcholine. Sodium ions. Calcium ions. Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape.

Mastering A&P Chapter 9 - Muscle and Muscle Tissue Diagram | Quizlet

Mastering A&P Chapter 9 - Muscle and Muscle Tissue
Mastering A&P Chapter 9 - Muscle and Muscle Tissue
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Terms in this set (104)

When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? motor endplates
terminal cisternae
sarcoplasmic reticulum
transverse or T tubules
Transverse or T tubules
T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. Action potentials. Acetylcholine. Sodium ions. Calcium ions. Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape.

5. Molecular mechanism of skeletal muscle contraction. Structure of skeletal muscle. The regulatory role of calcium ion – greek.doctor 5. Molecular mechanism of skeletal muscle contraction. Structure of skeletal muscle. The regulatory role of calcium ion
5. Molecular mechanism of skeletal muscle contraction. Structure of skeletal muscle. The regulatory role of calcium ion
Table of Contents
Learning objectives
General principles of muscles
Excitation-contraction coupling
General structure of muscle cells
Structure and contraction of skeletal muscle
Structure of skeletal muscle
Mechanism of excitation
Mechanism of contraction
Termination of contraction
 Structure of skeletal muscle. The regulatory role of calcium ion
Table of Contents
Learning objectives
General principles of muscles
Excitation-contraction coupling
General structure of muscle cells
Structure and contraction of skeletal muscle
Structure of skeletal muscle
Mechanism of excitation
Mechanism of contraction
Termination of contraction
Learning objectives
What does excitation-contraction coupling mean? What do we call the cell membrane, cytoplasm, and endoplasmic reticulum of a muscle cell? Describe the composition of skeletal muscle
Which proteins comprise the thin and thick filaments? What is the function of troponin and tropomyosin? What is the functional unit of striated muscle? What are the thin filaments anchored to? What are T-tubules? Which two proteins in the T-tubules are essential for excitation-contraction coupling, and what are their functions? Describe the mechanism of excitation of skeletal muscle
Describe the cross-bridge cycle
Describe the termination of contraction
General principles of muscles
There are three types of muscle tissue.

5. Molecular mechanism of skeletal muscle contraction. Structure of skeletal muscle. The regulatory role of calcium ion – greek.doctor

5. Molecular mechanism of skeletal muscle contraction. Structure of skeletal muscle. The regulatory role of calcium ion
5. Molecular mechanism of skeletal muscle contraction. Structure of skeletal muscle. The regulatory role of calcium ion
Table of Contents
Learning objectives
General principles of muscles
Excitation-contraction coupling
General structure of muscle cells
Structure and contraction of skeletal muscle
Structure of skeletal muscle
Mechanism of excitation
Mechanism of contraction
Termination of contraction

Structure of skeletal muscle. The regulatory role of calcium ion
Table of Contents
Learning objectives
General principles of muscles
Excitation-contraction coupling
General structure of muscle cells
Structure and contraction of skeletal muscle
Structure of skeletal muscle
Mechanism of excitation
Mechanism of contraction
Termination of contraction
Learning objectives
What does excitation-contraction coupling mean? What do we call the cell membrane, cytoplasm, and endoplasmic reticulum of a muscle cell? Describe the composition of skeletal muscle
Which proteins comprise the thin and thick filaments? What is the function of troponin and tropomyosin? What is the functional unit of striated muscle? What are the thin filaments anchored to? What are T-tubules? Which two proteins in the T-tubules are essential for excitation-contraction coupling, and what are their functions? Describe the mechanism of excitation of skeletal muscle
Describe the cross-bridge cycle
Describe the termination of contraction
General principles of muscles
There are three types of muscle tissue.

A&P 1 ch 9 & 10 Flashcards | Quizlet A&P 1 ch 9 & 10
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A&P Ch 9
Chapter 9
Bones of the Lower Leg
Bones
 What is a sarcomere
A sarcomere is the area between two Z discs. Describe a triad, and list the functions of the two structures within the triad
Successive grouping of the 3 membranous (terminal cistern, T tubule, and terminal cistern) along the sarcoplasmic reticulum. T-tubules conduct impulses to the deepest regions of the muscle cell and every sarcomere. Terminal cistern produce energy during contraction
Explain how muscle fibers are stimulated to contract by describing the events at the neuromuscular junction
Skeletal muscles are stimulated by somatic motor neurons Axons of motor neurons travel from the central nervous system via nerves to skeletal muscles Each axon forms several branches as it enters a muscle Each axon ending forms a neuromuscular junction with a single muscle fiber
Describe how an action potential is generated and moves from the motor neuron to the muscle fiber
End plate potential spreads to adjacent membrane areas
>Voltage-gated Na+ channels open
>Na+ influx decreases the membrane voltage toward a critical threshold
>If threshold is reached, an action potential is generated
>Local depolarization wave continues to spread, changing the permeability of the sarcolemma
Follow and describe the events of excitation-contraction coupling that lead to cross bridge cycling
Sequence of events by which transmission of an AP along the sarcolemma leads to sliding of the myofilaments
> Latent period: > Time when E-C coupling events occur
> Time between AP initiation and the beginning of contraction
> AP is propagated along sarcomere to T tubules
> Voltage-sensitive proteins stimulate
> Ca2+ release from SR
> Ca2+ is necessary for contraction
What is the role (s) of calcium, sodium (Na) and postassium (K) within a muscle contraction? Calcium-Muscle contraction is regulated by calcium ions, which will change thin filament into an activated state by binding to troponin. The binding of calcium to the troponin changes it's shape so the myosin binding sites on the actin (thin filament) are exposed
Sodium-
What is the role of acetylcholine (Ach) within a muscle contraction? When released ACh binds to receptors on the motor end plate, changing its permeability to Na+ ions. Na+ ions (due to an increased electrochemical gradient) rush into the sarcolemma. Be able to identify the function of any structure within the muscle contraction sequence?

A&P 1 ch 9 & 10 Flashcards | Quizlet

A&P 1 ch 9 & 10
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A&P Ch 9
Chapter 9
Bones of the Lower Leg
Bones

Skeletal Muscles | Summary, Innervation, Contract & Facts Skeletal Muscles
Skeletal Muscles
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Skeletal Muscles
Quick Navigation
Introduction
Quick Navigation
Organization
Skeletal Muscle Fiber
Sarcolemma
T-tubules
Myofibrils
Thin filaments
Thick filaments
Z-Disk
Sarcomere
Titin filaments
Sarcoplasm
Sarcoplasmic Reticulum
Innervation
Motor End Plate
Process of Innervation
Excitation-Contraction Coupling
Contraction and Relaxation
ATPase activity of Myosin Head
Role of Troponin in Contraction
Phases of Contraction
Relaxation
Energy Sources
Phosphocreatine
Glycolysis
Oxidative Metabolism
Summary
References
 The innervation of the skeletal muscle fiber also takes place via sarcolemma. The glycocalyx above the plasma membrane also contains several collagen fibers. It serves to hold the fibers together. At each end of the skeletal muscle fibers, the glycocalyx layers of several fibers merge and fuse with the tendon, attaching the muscle fibers to the bones. T-tubules
At some places along the length of the fiber, the sarcolemma invaginates into the cytoplasm to form transverse tubules called T-tubules. Each T-tubule is connected with smooth endoplasmic reticulum on either side to form a triad. These triads serve a special role in the contraction of skeletal muscles. Myofibrils
Each skeletal muscle fiber is composed of several hundred to several thousand of myofibrils. These myofibrils extend throughout the length of the skeletal muscle fiber. Each myofibril is further composed of two types of filaments, thin filaments and thick filaments.

Skeletal Muscles | Summary, Innervation, Contract & Facts

Skeletal Muscles
Skeletal Muscles
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Skeletal Muscles
Quick Navigation
Introduction
Quick Navigation
Organization
Skeletal Muscle Fiber
Sarcolemma
T-tubules
Myofibrils
Thin filaments
Thick filaments
Z-Disk
Sarcomere
Titin filaments
Sarcoplasm
Sarcoplasmic Reticulum
Innervation
Motor End Plate
Process of Innervation
Excitation-Contraction Coupling
Contraction and Relaxation
ATPase activity of Myosin Head
Role of Troponin in Contraction
Phases of Contraction
Relaxation
Energy Sources
Phosphocreatine
Glycolysis
Oxidative Metabolism
Summary
References

The innervation of the skeletal muscle fiber also takes place via sarcolemma. The glycocalyx above the plasma membrane also contains several collagen fibers. It serves to hold the fibers together. At each end of the skeletal muscle fibers, the glycocalyx layers of several fibers merge and fuse with the tendon, attaching the muscle fibers to the bones. T-tubules
At some places along the length of the fiber, the sarcolemma invaginates into the cytoplasm to form transverse tubules called T-tubules. Each T-tubule is connected with smooth endoplasmic reticulum on either side to form a triad. These triads serve a special role in the contraction of skeletal muscles. Myofibrils
Each skeletal muscle fiber is composed of several hundred to several thousand of myofibrils. These myofibrils extend throughout the length of the skeletal muscle fiber. Each myofibril is further composed of two types of filaments, thin filaments and thick filaments.

LP 10 Flashcards | Quizlet LP 10
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LP 10
Muscle Tissue Practice Exam
 ...
What is the function of acetylcholine in regard to muscle contraction? ...
What are the steps involved with excitation-contraction coupling? ...
When actin and myosin form a connection during muscle contraction, what is that connection called? ...
What is the T-tubule, and what is its function? ...
What are the different ways that muscle gets its ATP, depending on the length of activity? ...
What needs to occur in order for a muscle to relax after contracting? ...
What is the role of connectin in muscle contraction and/or relaxation? ...
What is "treppe?" ...
What is the role of acetylcholinesterase? ...
What are the anatomical components found in a sarcomere?

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Anatomy Chapter 10
LP 10
Muscle Tissue Practice Exam

...
What is the function of acetylcholine in regard to muscle contraction? ...
What are the steps involved with excitation-contraction coupling? ...
When actin and myosin form a connection during muscle contraction, what is that connection called? ...
What is the T-tubule, and what is its function? ...
What are the different ways that muscle gets its ATP, depending on the length of activity? ...
What needs to occur in order for a muscle to relax after contracting? ...
What is the role of connectin in muscle contraction and/or relaxation? ...
What is "treppe?" ...
What is the role of acetylcholinesterase? ...
What are the anatomical components found in a sarcomere?

A&P 1 ch 9 & 10 Flashcards | Quizlet A&P 1 ch 9 & 10
A&P 1 ch 9 & 10
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A&P Ch 9
Chapter 9
Bones of the Lower Leg
Bones
 stores large amounts of glycosomes
Glycosome: provide glucose (sugar) during periods of muscle cell activity
Myoglobin: stores oxygen;Carry and store iron for muscle cells
Describe a myofibril
A myofibril is a bundle of contractile filaments (myofilaments), 1-2 μm in diameter, that are arranged in parallel groups in the cytoplasm of striated muscle cells. Why does a myofibril appear striated? Repeated presence of sarcomere on the myofibril. What is a sarcomere
A sarcomere is the area between two Z discs. Describe a triad, and list the functions of the two structures within the triad
Successive grouping of the 3 membranous (terminal cistern, T tubule, and terminal cistern) along the sarcoplasmic reticulum. T-tubules conduct impulses to the deepest regions of the muscle cell and every sarcomere. Terminal cistern produce energy during contraction
Explain how muscle fibers are stimulated to contract by describing the events at the neuromuscular junction
Skeletal muscles are stimulated by somatic motor neurons Axons of motor neurons travel from the central nervous system via nerves to skeletal muscles Each axon forms several branches as it enters a muscle Each axon ending forms a neuromuscular junction with a single muscle fiber
Describe how an action potential is generated and moves from the motor neuron to the muscle fiber
End plate potential spreads to adjacent membrane areas
>Voltage-gated Na+ channels open
>Na+ influx decreases the membrane voltage toward a critical threshold
>If threshold is reached, an action potential is generated
>Local depolarization wave continues to spread, changing the permeability of the sarcolemma
Follow and describe the events of excitation-contraction coupling that lead to cross bridge cycling
Sequence of events by which transmission of an AP along the sarcolemma leads to sliding of the myofilaments
> Latent period: > Time when E-C coupling events occur
> Time between AP initiation and the beginning of contraction
> AP is propagated along sarcomere to T tubules
> Voltage-sensitive proteins stimulate
> Ca2+ release from SR
> Ca2+ is necessary for contraction
What is the role (s) of calcium, sodium (Na) and postassium (K) within a muscle contraction?

A&P 1 ch 9 & 10 Flashcards | Quizlet

T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases | Skeletal Muscle | Full Text
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Published: 13 July 2011
T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
Lama Al-Qusairi
1, 2, 3, 4, 5, 6
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Jocelyn Laporte
1, 2, 3, 4, 5
Skeletal Muscle
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1, Article number: 26 ( 2011 ) Cite this article
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Abstract
In skeletal muscle, the excitation-contraction (EC) coupling machinery mediates the translation of the action potential transmitted by the nerve into intracellular calcium release and muscle contraction. EC coupling requires a highly specialized membranous structure, the triad, composed of a central T-tubule surrounded by two terminal cisternae from the sarcoplasmic reticulum. While several proteins located on these structures have been identified, mechanisms governing T-tubule biogenesis and triad formation remain largely unknown. Here, we provide a description of triad structure and plasticity and review the role of proteins that have been linked to T-tubule biogenesis and triad formation and/or maintenance specifically in skeletal muscle: caveolin 3, amphiphysin 2, dysferlin, mitsugumins, junctophilins, myotubularin, ryanodine receptor, and dihydhropyridine Receptor. The importance of these proteins in triad biogenesis and subsequently in muscle contraction is sustained by studies on animal models and by the direct implication of most of these proteins in human myopathies. Introduction
To trigger skeletal muscle contraction, the action potential generated by motor neurons is transmitted through motor nerves to muscle cells. The excitation-contraction (EC) coupling, i.e. signal transmission from the sarcolemma to the actin/myosin apparatus, is mediated by a second messenger, calcium ions.

Skeletal muscle physiology | BJA Education | Oxford Academic Skeletal muscle physiology
Skeletal muscle physiology
Published:
Subject
Issue Section:
Key points
Electrical events in muscle contraction
Excitation-contraction coupling
Contractile structures
Force transmission
Determinants of force of contraction
Summation
Recruitment
Energy for contraction
Muscle fibre-types
Further reading
 Skeletal muscle sarcolemma is characterized by invaginations called transverse- or t-tubules that run perpendicular to the surface of the cell deep into its body. By passing down the t-tubular membrane, the action potential is carried to the structures responsible for transducing an electrical into a chemical signal that will trigger activation of the contractile elements. Excitation-contraction coupling
This term encompasses the processes by which the surface membrane action potential leads to interaction of the intracellular contractile elements. The t-tubular membrane contains the highest density in the body of binding sites for dihydropyridine compounds, such as nifedipine. This finding was initially assumed to suggest that arrival of the action potential in the t-tubules opened voltage-gated Ca 2+ channels. We now know that, although the t-tubular dihydropyridine receptors show marked amino acid homology with L-type voltage gated Ca 2+ channels of other tissues, they do not function as Ca 2+ channels. Their role in skeletal muscle is that of voltage sensors. When the action potential arrives in the t-tubule, the change in membrane potential leads to a conformational change in the α-subunit of the dihydropyridine receptor. This subunit consists of four transmembrane domains each of six segments ( Fig. 1 ).

Skeletal muscle physiology | BJA Education | Oxford Academic

Skeletal muscle physiology
Skeletal muscle physiology
Published:
Subject
Issue Section:
Key points
Electrical events in muscle contraction
Excitation-contraction coupling
Contractile structures
Force transmission
Determinants of force of contraction
Summation
Recruitment
Energy for contraction
Muscle fibre-types
Further reading

Skeletal muscle sarcolemma is characterized by invaginations called transverse- or t-tubules that run perpendicular to the surface of the cell deep into its body. By passing down the t-tubular membrane, the action potential is carried to the structures responsible for transducing an electrical into a chemical signal that will trigger activation of the contractile elements. Excitation-contraction coupling
This term encompasses the processes by which the surface membrane action potential leads to interaction of the intracellular contractile elements. The t-tubular membrane contains the highest density in the body of binding sites for dihydropyridine compounds, such as nifedipine. This finding was initially assumed to suggest that arrival of the action potential in the t-tubules opened voltage-gated Ca 2+ channels. We now know that, although the t-tubular dihydropyridine receptors show marked amino acid homology with L-type voltage gated Ca 2+ channels of other tissues, they do not function as Ca 2+ channels. Their role in skeletal muscle is that of voltage sensors. When the action potential arrives in the t-tubule, the change in membrane potential leads to a conformational change in the α-subunit of the dihydropyridine receptor. This subunit consists of four transmembrane domains each of six segments ( Fig. 1 ).

Difference Between Skeletal Muscle and Cardiac Muscle | Compare the Difference Between Similar Terms Difference Between Skeletal Muscle and Cardiac Muscle
Difference Between Skeletal Muscle and Cardiac Muscle
CONTENTS
What is Skeletal Muscle?
What is Cardiac Muscle?
What are the Similarities Between Skeletal Muscle and Cardiac Muscle?
What is the Difference Between Skeletal Muscle and Cardiac Muscle?
Summary – Skeletal Muscle vs Cardiac Muscle
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 Cardiac Muscle
Cardiac muscles also exhibit cross striations by alternating thick and thin filaments. Under the electron microscope view, actin filaments appear as thin bands while myosin filaments appear as thick and darker bands. Cardiac muscle fibres are mostly branched. T-tubules in the cardiac muscle are larger, broader and run along the Z-Discs. Intercalated discs connect cardiac myocytes to an electrochemical syncytium and are responsible for force transmissions during muscle contraction. T-tubules play an important role in excitation-contraction-coupling (ECG). What are the Similarities Between Skeletal Muscle and Cardiac Muscle? Skeletal muscle and cardiac muscle are two of the three types of muscles present in our body. Both are striated muscles. Therefore, they contain myofibrils and sarcomeres.

Difference Between Skeletal Muscle and Cardiac Muscle | Compare the Difference Between Similar Terms

Difference Between Skeletal Muscle and Cardiac Muscle
Difference Between Skeletal Muscle and Cardiac Muscle
CONTENTS
What is Skeletal Muscle?
What is Cardiac Muscle?
What are the Similarities Between Skeletal Muscle and Cardiac Muscle?
What is the Difference Between Skeletal Muscle and Cardiac Muscle?
Summary – Skeletal Muscle vs Cardiac Muscle
Reference:
Image Courtesy:
About the Author: Samanthi
Leave a Reply
Cancel reply

Cardiac Muscle
Cardiac muscles also exhibit cross striations by alternating thick and thin filaments. Under the electron microscope view, actin filaments appear as thin bands while myosin filaments appear as thick and darker bands. Cardiac muscle fibres are mostly branched. T-tubules in the cardiac muscle are larger, broader and run along the Z-Discs. Intercalated discs connect cardiac myocytes to an electrochemical syncytium and are responsible for force transmissions during muscle contraction. T-tubules play an important role in excitation-contraction-coupling (ECG). What are the Similarities Between Skeletal Muscle and Cardiac Muscle? Skeletal muscle and cardiac muscle are two of the three types of muscles present in our body. Both are striated muscles. Therefore, they contain myofibrils and sarcomeres.

Therefore, BIN1-like membrane scaffold proteins may help localize particular pools of ion channel proteins to membrane subdomains for compartmentalized regulation of ion channel activity and function. Similarly, ankyrin B can play a role similar to BIN1 in clustering NCX/NKA/InsP3 complex to microdomains distinct from the dyads. 71 Integrity of NCX/NKA/InsP3 complex is critical in removing calcium from the clefts between T-tubule surface and SR membrane, facilitating calcium decline during relaxation. Therefore, intracellular calcium equilibrium can be achieved by balancing calcium entry through LTCC clustered at BIN1-membrane and calcium removal by NCX anchored at ankyrin B-induced membrane. View chapter Purchase book
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URL: https://www.sciencedirect.com/science/article/pii/B9780128020029000029
Functional Organization of Vertebrate Plasma Membrane
Crystal F. Kline, Peter J. Mohler, in Current Topics in Membranes, 2013
2.4 T-tubules, physiology, and disease
T-tubule structure and function is severely compromised in human heart failure and in small and large animal models of cardiovascular disease ( Balijepalli et al., 2003; Louch et al., 2004 ). Animal models of heart failure exhibit T-tubule disorganization that appears to result from various myocardial insults, including sustained tachycardia ( Balijepalli et al.,

T-tubule | Psychology Wiki | Fandom

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 Although the diversity of estimates of the extent of the t-tubules within a species makes it impossible to determine whether there may be differences between species, it is tempting to speculate that the extent of the t-tubules varies between species depending on cell size (surface area/volume ratio) and heart rate if the t-tubules are necessary to produce synchronous Ca 2+ release throughout the cell (see Coupling of Ca 2+ Entry and Ca 2+ Release, later) and, hence, synchronous contraction. Although we are unaware of any differences related to cell size, the density of the t-tubular network is greater in the mouse, which has a resting heart rate of 300 to 400 bpm, than in the pig, which has a heart rate of <100 bpm. 1
T-Tubule Development Is Labile
Ventricular myocytes isolated from neonatal hearts show little evidence of t-tubule development, 4,18 and cells kept in culture for 6 days show a progressive decrease of t-tubule density. 19 T-tubule structure has also been reported to change in myocytes from failing hearts (see T-Tubule Development and Morphology in Hypertrophy and Failure). However, the mechanisms underlying the expression and maintenance of the t-tubules are not clear. Once formed, the ability of the tubular system to maintain its remarkable degree of structure despite the forces exerted during the normal contraction cycle may be due to the presence of a “scaffold” of focal adhesion molecules, membrane-associated proteins, and basal lamina proteins. 20
Proteins Present in the T-Tubule Membrane
The function of the t-tubules depends not only on their structure but also on the proteins within, and adjacent to, the t-tubule membrane. Immunohistochemical techniques have been widely used to investigate the location of proteins within cardiac ventricular myocytes. Such studies have shown marked variations in the distribution of membrane proteins, although a distinction needs to be drawn between the fraction of a particular type of protein located at the t-tubule and whether this is greater than the fraction of the total cell membrane located within the t-tubules, ie, whether protein density is higher (concentrated) at the t-tubule. This is discussed further in Interpretation of Immunohistochemical Data and in Conclusions and Unanswered Questions.

T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References

 The plasmamembrane of a musclecell, called the sarcolemma, separates the sarcoplasm(muscle cellcytoplasm) from the extracellular surroundings. Within the sarcoplasmof each...
Full article >>>
A T-tubule is a deep invagination of the sarcolemma, which is the plasmamembrane, only found in skeletal and cardiac musclecells. These invaginations allow depolarizationof the membrane to quickly penetrate to the interior of the cell. Full article >>>
... a role in remodelling of sarcolemma, sarcoplasmic reticulum, and myofibrils. Remodelling of extracellular matrix and sarcolemmaas well as changes in signal ...
Full article >>>
... the Na+-Ca2+ exchange activity of cardiac sarcolemmain reconstituted vesicles. ... in reconstituted vesicles from bovine cardiac sarcolemma. J Biol Chem. ... Full article >>>
To permeabilize the sarcolemmaof intact fibres, saponin (Fluka Chem. ... Dystrophin protects the sarcolemmafrom stresses developed during musclecontraction. ... Full article >>>
b. t-tubules - invaginations of the sarcolemma... sarcolemmaand t-tubules repolarize.

The plasmamembrane of a musclecell, called the sarcolemma, separates the sarcoplasm(muscle cellcytoplasm) from the extracellular surroundings. Within the sarcoplasmof each...
Full article >>>
A T-tubule is a deep invagination of the sarcolemma, which is the plasmamembrane, only found in skeletal and cardiac musclecells. These invaginations allow depolarizationof the membrane to quickly penetrate to the interior of the cell. Full article >>>
... a role in remodelling of sarcolemma, sarcoplasmic reticulum, and myofibrils. Remodelling of extracellular matrix and sarcolemmaas well as changes in signal ...
Full article >>>
... the Na+-Ca2+ exchange activity of cardiac sarcolemmain reconstituted vesicles. ... in reconstituted vesicles from bovine cardiac sarcolemma. J Biol Chem. ... Full article >>>
To permeabilize the sarcolemmaof intact fibres, saponin (Fluka Chem. ... Dystrophin protects the sarcolemmafrom stresses developed during musclecontraction. ... Full article >>>
b. t-tubules - invaginations of the sarcolemma... sarcolemmaand t-tubules repolarize.

Anatomy & Physiology chapter 11 Physiology of the Muscle Flashcards - Cram.com Anatomy & Physiology Chapter 11 Physiology Of The Muscle
Anatomy & Physiology Chapter 11 Physiology Of The Muscle
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What are the three major functions of the skeletal muscles? (a) endomysium, (b) perimysium, (c) epimysium

Name some features of the muscle cell that are not found in other types of cells
Excitability, contractibility, and extensibility

What causes the striations observed in skeletal muscle fibers? The striations r a result of the A bands of sarcomeres appearing as relatively wide, dark stripes under the microscope, which alternate with narrower, lighter colored stripes formed by the I bands

Why is the triad relationship between T tubules and the SR important
The triad allows an electrical impulse traveling along a T tubule to stimulate the membranes of adjacent sacs of the SR

Describe the structure of thin and thick myofilaments, and name the kinds of proteins that compose them
Thin filament (actin, troponin,& tropomyosin): molecules strung 2gether like beads 2 form 2 fibrous strands that twist around each other. Describe the structure of thin and thick myofilaments, and name the kinds of proteins that compose them
Thick filament (myosin): shaped like golf clubs,w/ their long shafts bundled together 2 form a thick filament & their “heads” sticking out from the bundle

What is the role of calcium ions (Ca++) in muscle contraction? Calcium ions released from the SR bind to troponin in the thin filament allow tropomyosin 2 shift frm its position blcking the active sites of actin molecules, thus initiating the chemical reactions that produce contractions

Where does the energy stored in ATP come from? Catabolism of foods

What is the role of myoglobin in muscle fibers?

Anatomy & Physiology chapter 11 Physiology of the Muscle Flashcards - Cram.com

Anatomy & Physiology Chapter 11 Physiology Of The Muscle
Anatomy & Physiology Chapter 11 Physiology Of The Muscle
Card Range To Study
32 Cards in this Set

H to show hint; A reads text to speech; Share
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32 Cards in this Set
Front
Back

What are the three major functions of the skeletal muscles? (a) endomysium, (b) perimysium, (c) epimysium

Name some features of the muscle cell that are not found in other types of cells
Excitability, contractibility, and extensibility

What causes the striations observed in skeletal muscle fibers? The striations r a result of the A bands of sarcomeres appearing as relatively wide, dark stripes under the microscope, which alternate with narrower, lighter colored stripes formed by the I bands

Why is the triad relationship between T tubules and the SR important
The triad allows an electrical impulse traveling along a T tubule to stimulate the membranes of adjacent sacs of the SR

Describe the structure of thin and thick myofilaments, and name the kinds of proteins that compose them
Thin filament (actin, troponin,& tropomyosin): molecules strung 2gether like beads 2 form 2 fibrous strands that twist around each other. Describe the structure of thin and thick myofilaments, and name the kinds of proteins that compose them
Thick filament (myosin): shaped like golf clubs,w/ their long shafts bundled together 2 form a thick filament & their “heads” sticking out from the bundle

What is the role of calcium ions (Ca++) in muscle contraction? Calcium ions released from the SR bind to troponin in the thin filament allow tropomyosin 2 shift frm its position blcking the active sites of actin molecules, thus initiating the chemical reactions that produce contractions

Where does the energy stored in ATP come from? Catabolism of foods

What is the role of myoglobin in muscle fibers?

10.3 Muscle Fiber Excitation, Contraction, and Relaxation – Anatomy & Physiology 10.3 Muscle Fiber Excitation, Contraction, and Relaxation
10.3 Muscle Fiber Excitation, Contraction, and Relaxation
Learning Objectives
The Neuromuscular Junction
External Website
Excitation-Contraction Coupling
Contraction and Relaxation
External Website
Cross-Bridge Cycling
Sources of ATP
Relaxation of a Skeletal Muscle
Muscle Strength
Interactive Link Questions
Review Questions
Critical Thinking Questions
Glossary
Solutions
 Muscle contraction usually stops when signaling from the motor neuron ends, which repolarizes the sarcolemma and T-tubules, and closes the calcium channels in the SR. Ca ++ ions are then pumped back into the SR, which causes the tropomyosin to re-cover the binding sites on actin ( Figure 10.3.2 ). External Website
The release of calcium ions initiates muscle contractions. Watch this video to learn more about the role of calcium. ( a) What are “T-tubules” and what is their role? ( b) Please describe how actin-binding sites are made available for cross-bridging with myosin heads during contraction. Cross-Bridge Cycling
FROM sliding filament section… leads into cross-bridge cylcing section….. “But each head can only pull a very short distance before it has reached its limit and must be “re-cocked” before it can pull again, a step that requires ATP.” As you have learned, during contraction the myosin heads of the thick filament bind to actin and pull the thin filament which shortens the sarcomere and produces force. However, the length of the mysoin hinge region allows each myosin head to only pull a very short distance before it must reset to pull again. For thin filaments to continue to slide past thick filaments during muscle contraction, myosin heads must pull the actin at the binding sites, detach, re-cock, attach to more binding sites, pull, detach, re-cock, etc.

Muscle contraction usually stops when signaling from the motor neuron ends, which repolarizes the sarcolemma and T-tubules, and closes the calcium channels in the SR. Ca ++ ions are then pumped back into the SR, which causes the tropomyosin to re-cover the binding sites on actin ( Figure 10.3.2 ). External Website
The release of calcium ions initiates muscle contractions. Watch this video to learn more about the role of calcium. ( a) What are “T-tubules” and what is their role? ( b) Please describe how actin-binding sites are made available for cross-bridging with myosin heads during contraction. Cross-Bridge Cycling
FROM sliding filament section… leads into cross-bridge cylcing section….. “But each head can only pull a very short distance before it has reached its limit and must be “re-cocked” before it can pull again, a step that requires ATP.” As you have learned, during contraction the myosin heads of the thick filament bind to actin and pull the thin filament which shortens the sarcomere and produces force. However, the length of the mysoin hinge region allows each myosin head to only pull a very short distance before it must reset to pull again. For thin filaments to continue to slide past thick filaments during muscle contraction, myosin heads must pull the actin at the binding sites, detach, re-cock, attach to more binding sites, pull, detach, re-cock, etc.

 -Myofilaments (or filaments) are ultramicroscopic, thread-like structures found in myofibrils. -In other words, the myofilaments are bundled together to make a myofibril. What are the 2 types of Myofilaments? 1) thick myofilaments
2) thin myofilaments
What is a Sarcomere? The contractile unit of myofibrils. It is the segment between 2 successive Z-Lines. What are the T tubules and what is their chief function? - T tubules are transverse tubules formed by inward extensions of the sarcolemma. -Function is to allow electrical impulses traveling along the sarcomere to move deeper into the cell. What do impulses from the T tubules do to the sarcoplasmic reticulum?

-Myofilaments (or filaments) are ultramicroscopic, thread-like structures found in myofibrils. -In other words, the myofilaments are bundled together to make a myofibril. What are the 2 types of Myofilaments? 1) thick myofilaments
2) thin myofilaments
What is a Sarcomere? The contractile unit of myofibrils. It is the segment between 2 successive Z-Lines. What are the T tubules and what is their chief function? - T tubules are transverse tubules formed by inward extensions of the sarcolemma. -Function is to allow electrical impulses traveling along the sarcomere to move deeper into the cell. What do impulses from the T tubules do to the sarcoplasmic reticulum?

 What is the difference between a dyad and triad in skeletal cardiac muscle? - Answers
In skeletal muscle, a triad is formed when a T-Tubule is flanked
on either side by the calcium containing Terminal Cisternae of the
Sarcoplasmic Reticulum, at the level of the Z-line. The intimate
association of these three membranous sturctures (Terminal
Cisternae---T-Tubule---Terminal Cisternae) for a Triad. This
differs from a diad (or Dyad), in cardiac muscle where the T-Tubule
is only intimately associated with ONE Terminal Cisternae. Home

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What is the difference between a dyad and triad in skeletal cardiac muscle? Asked by Wiki User
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Answered 2008-10-10 21:49:34
In skeletal muscle, a triad is formed when a T-Tubule is flanked
on either side by the calcium containing Terminal Cisternae of the
Sarcoplasmic Reticulum, at the level of the Z-line. The intimate
association of these three membranous sturctures (Terminal
Cisternae---T-Tubule---Terminal Cisternae) for a Triad. This
differs from a diad (or Dyad), in cardiac muscle where the T-Tubule
is only intimately associated with ONE Terminal Cisternae. 012
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What is the difference between a dyad and triad in skeletal cardiac muscle? - Answers
In skeletal muscle, a triad is formed when a T-Tubule is flanked
on either side by the calcium containing Terminal Cisternae of the
Sarcoplasmic Reticulum, at the level of the Z-line. The intimate
association of these three membranous sturctures (Terminal
Cisternae---T-Tubule---Terminal Cisternae) for a Triad. This
differs from a diad (or Dyad), in cardiac muscle where the T-Tubule
is only intimately associated with ONE Terminal Cisternae. Home

Science

Math and Arithmetic

History

Literature and Language

Technology

Health

🧑⚖
Law & Legal Issues

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All Topics

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        Leaderboard
        Related Topics
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Human Anatomy and Physiology

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What is the difference between a dyad and triad in skeletal cardiac muscle? Asked by Wiki User
See Answer
Top Answer
Wiki User
Answered 2008-10-10 21:49:34
In skeletal muscle, a triad is formed when a T-Tubule is flanked
on either side by the calcium containing Terminal Cisternae of the
Sarcoplasmic Reticulum, at the level of the Z-line. The intimate
association of these three membranous sturctures (Terminal
Cisternae---T-Tubule---Terminal Cisternae) for a Triad. This
differs from a diad (or Dyad), in cardiac muscle where the T-Tubule
is only intimately associated with ONE Terminal Cisternae. 012
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What are the similarities between skeletal and cardiac muscle cells?

Mastering A&P Muscular System Flashcards | Quizlet Mastering A&P Muscular System
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Terms in this set (70)
 increased excitability of the muscle fibers at the site of injection. increased levels of ACh in the synaptic cleft. muscle paralysis at the site of injection. muscle paralysis at the site of injection. What are the components of a triad? One actin and one myosin
Two terminal cisternae of the SR and one calcium ion
Two thin filaments and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Excitation-contraction coupling results in an increase of calcium ion concentration: in the cytosol of the muscle fiber. in the sarcoplasmic reticulum. in the T-tubules. in the synaptic cleft.

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Terms in this set (70)

increased excitability of the muscle fibers at the site of injection. increased levels of ACh in the synaptic cleft. muscle paralysis at the site of injection. muscle paralysis at the site of injection. What are the components of a triad? One actin and one myosin
Two terminal cisternae of the SR and one calcium ion
Two thin filaments and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Excitation-contraction coupling results in an increase of calcium ion concentration: in the cytosol of the muscle fiber. in the sarcoplasmic reticulum. in the T-tubules. in the synaptic cleft.

Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum | Neupsy Key Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum
Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum
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 Free sarcoplasmic reticulum constitutes the remainder of the intrafiber sarcoplasmic reticulum membrane system. It is not associated with the T tubule system and functions in Ca 2+ reuptake into the sarcoplasmic reticulum. It has a large number of Ca 2+ adenosine triphosphatase (ATPase) pumps on its surface that function in the energy-dependent reuptake of sarcoplasmic Ca 2+ and therefore plays a role in muscle relaxation rather than excitation and contraction. A motor nerve action potential propagates down the motor nerve axon to the nerve terminal, causing release of acetylcholine (ACh) into the synaptic cleft of the neuromuscular junction. After binding of acetylcholine to the postsynaptic muscle membrane acetylcholine receptor (AChR), there is generation of an end-plate potential. Suprathreshold end-plate potentials generate muscle fiber action potentials. These propagate along the sarcolemma, depolarizing the muscle membrane sequentially as it travels along the membrane. The action potential continues down the T tubules. Depolarization of the T tubule membrane activates the voltage-gated Ca 2+ channel, thus activating the ryanodine receptor, releasing large amounts of Ca 2+ from the sarcoplasmic reticulum into the sarcoplasm. This leads to cross-bridge formation between thin and thick filaments, activation of the cross-bridge cycle, sliding of the thick and thin filaments past one another, sarcomere shortening, and eventually muscle contraction.

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Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum
Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum
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Free sarcoplasmic reticulum constitutes the remainder of the intrafiber sarcoplasmic reticulum membrane system. It is not associated with the T tubule system and functions in Ca 2+ reuptake into the sarcoplasmic reticulum. It has a large number of Ca 2+ adenosine triphosphatase (ATPase) pumps on its surface that function in the energy-dependent reuptake of sarcoplasmic Ca 2+ and therefore plays a role in muscle relaxation rather than excitation and contraction. A motor nerve action potential propagates down the motor nerve axon to the nerve terminal, causing release of acetylcholine (ACh) into the synaptic cleft of the neuromuscular junction. After binding of acetylcholine to the postsynaptic muscle membrane acetylcholine receptor (AChR), there is generation of an end-plate potential. Suprathreshold end-plate potentials generate muscle fiber action potentials. These propagate along the sarcolemma, depolarizing the muscle membrane sequentially as it travels along the membrane. The action potential continues down the T tubules. Depolarization of the T tubule membrane activates the voltage-gated Ca 2+ channel, thus activating the ryanodine receptor, releasing large amounts of Ca 2+ from the sarcoplasmic reticulum into the sarcoplasm. This leads to cross-bridge formation between thin and thick filaments, activation of the cross-bridge cycle, sliding of the thick and thin filaments past one another, sarcomere shortening, and eventually muscle contraction.

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 ACh diffuses into the synaptic cleft, binds to the receptor proteins on the junctional folds of the muscle sarcolemma (motor end plate), and initiates graded potentials. These graded potentials sum to an action potential, thus initiating excitement of the muscle fiber. The action potential propagates along the sarcolemma. As the action potential spreads down the T tubules of the triads, voltage-sensitive tubule proteins change shape. How does the shape change of these proteins lead to contraction? It allows calcium to exit the sarcoplasmic reticulum and enter the cytosol. *As the action potential propagates, it changes the shape of T tubule proteins. These proteins are linked to calcium channels in the terminal cisterns of the sarcoplasmic reticulum. When these proteins' calcium channels open, a massive amount of calcium flows into the cytosol. Which selection correctly describes the role of calcium in coupling?

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ACh diffuses into the synaptic cleft, binds to the receptor proteins on the junctional folds of the muscle sarcolemma (motor end plate), and initiates graded potentials. These graded potentials sum to an action potential, thus initiating excitement of the muscle fiber. The action potential propagates along the sarcolemma. As the action potential spreads down the T tubules of the triads, voltage-sensitive tubule proteins change shape. How does the shape change of these proteins lead to contraction? It allows calcium to exit the sarcoplasmic reticulum and enter the cytosol. *As the action potential propagates, it changes the shape of T tubule proteins. These proteins are linked to calcium channels in the terminal cisterns of the sarcoplasmic reticulum. When these proteins' calcium channels open, a massive amount of calcium flows into the cytosol. Which selection correctly describes the role of calcium in coupling?

Cardiac T-Tubule Microanatomy and Function | Physiological Reviews Cardiac T-Tubule Microanatomy and Function
Cardiac T-Tubule Microanatomy and Function
Abstract
I. INTRODUCTION
II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
B. Gross Morphology and Geometry
C. Membrane Ultrastructure and Microdomains
1. cBIN1 microfolds: microdomains supporting LTCC-RyR dyads
2. Caveoli (caveolae): β-AR/LTCC signaling hubs
3. Ankyrin B microdomains: NCX/NKA/InsP 3 macromolecular complex
D. Peri-Membrane Cytoskeleton Scaffolds at Cardiac T-Tubules
1. Actin filaments, tropomyosin, and N-WASP
2. Costamere complex and t-tubule membrane-associated scaffolds
3. Myofilament structural proteins
E. Variation in Cardiac T-Tubule Geometry
III. TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
1. Ca 2+ handling proteins
2. Na + handling proteins
3. K + handling proteins
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
1. LTCC trafficking and clustering to dyads through BIN1
2. RyR recruitment to dyads through BIN1
3. Junctophilin-2 in t-tubule-jSR junctional membrane complex formation
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments
 Cardiac t-tubules are also substantially remodeled during heart failure ( 38, 52, 89, 97, 98, 108, 130 - 134, 180, 202, 207, 208, 220, 224, 230 ). In addition to the observed loss and gross diminishment of the t-tubule network, protein components at t-tubules including ion channels and signaling molecules are reported to be either reduced at the t-tubule surface or redistributed elsewhere to non-t-tubule sarcolemma ( 20, 93, 134 ). Loss of complex t-tubules in heart failure not only causes impaired contractile function due to disrupted dyads and the resultant EC uncoupling, but also alters local concentration gradients and increases susceptibility to ventricular arrhythmia ( 66, 85, 91, 157, 163, 179, 181, 213 ). The molecular and cellular mechanisms of t-tubule remodeling in failing cardiomyocytes, in particular the alterations in t-tubule membrane ultrastructure and subdomains, is an active area of interest among cardiac biologists. This review summarizes and cites the current knowledge of cardiac t-tubule morphology, structure, components, and physiological functions, with emphasis on the organization and function of microdomains within t-tubules. The dynamic life cycle of t-tubule membrane and protein components, as well as the current understanding of microdomain remodeling in heart failure, will also be discussed. II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
Striated muscle cells have a unique membrane system, the transverse-tubules (t-tubules), or more precisely, the transverse-axial-tubular system. T-tubules are sarcolemma invaginations formed by membrane tubules that are primarily perpendicular to myocyte longitudinal edges. These membrane tubular structures are interconnected in a complex network.

Cardiac T-Tubule Microanatomy and Function | Physiological Reviews

Cardiac T-Tubule Microanatomy and Function
Cardiac T-Tubule Microanatomy and Function
Abstract
I. INTRODUCTION
II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
B. Gross Morphology and Geometry
C. Membrane Ultrastructure and Microdomains
1. cBIN1 microfolds: microdomains supporting LTCC-RyR dyads
2. Caveoli (caveolae): β-AR/LTCC signaling hubs
3. Ankyrin B microdomains: NCX/NKA/InsP 3 macromolecular complex
D. Peri-Membrane Cytoskeleton Scaffolds at Cardiac T-Tubules
1. Actin filaments, tropomyosin, and N-WASP
2. Costamere complex and t-tubule membrane-associated scaffolds
3. Myofilament structural proteins
E. Variation in Cardiac T-Tubule Geometry
III. TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
1. Ca 2+ handling proteins
2. Na + handling proteins
3. K + handling proteins
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
1. LTCC trafficking and clustering to dyads through BIN1
2. RyR recruitment to dyads through BIN1
3. Junctophilin-2 in t-tubule-jSR junctional membrane complex formation
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments

Cardiac t-tubules are also substantially remodeled during heart failure ( 38, 52, 89, 97, 98, 108, 130 - 134, 180, 202, 207, 208, 220, 224, 230 ). In addition to the observed loss and gross diminishment of the t-tubule network, protein components at t-tubules including ion channels and signaling molecules are reported to be either reduced at the t-tubule surface or redistributed elsewhere to non-t-tubule sarcolemma ( 20, 93, 134 ). Loss of complex t-tubules in heart failure not only causes impaired contractile function due to disrupted dyads and the resultant EC uncoupling, but also alters local concentration gradients and increases susceptibility to ventricular arrhythmia ( 66, 85, 91, 157, 163, 179, 181, 213 ). The molecular and cellular mechanisms of t-tubule remodeling in failing cardiomyocytes, in particular the alterations in t-tubule membrane ultrastructure and subdomains, is an active area of interest among cardiac biologists. This review summarizes and cites the current knowledge of cardiac t-tubule morphology, structure, components, and physiological functions, with emphasis on the organization and function of microdomains within t-tubules. The dynamic life cycle of t-tubule membrane and protein components, as well as the current understanding of microdomain remodeling in heart failure, will also be discussed. II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
Striated muscle cells have a unique membrane system, the transverse-tubules (t-tubules), or more precisely, the transverse-axial-tubular system. T-tubules are sarcolemma invaginations formed by membrane tubules that are primarily perpendicular to myocyte longitudinal edges. These membrane tubular structures are interconnected in a complex network.

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 When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? motor endplates
terminal cisternae
sarcoplasmic reticulum
transverse or T tubules
Transverse or T tubules
T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. Action potentials. Acetylcholine. Sodium ions. Calcium ions. Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape.

When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? motor endplates
terminal cisternae
sarcoplasmic reticulum
transverse or T tubules
Transverse or T tubules
T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. Action potentials. Acetylcholine. Sodium ions. Calcium ions. Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape.

 Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell.[1] T-tubule structure may be affected by disease, potentially contributing to heart failureand arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1Structure
1.1Regulators
2Function
2.1Excitation-contraction coupling
2.2Calcium control
2.3Detubulation
3History
4Clinical significance
5See also
6References
Structure[edit]
T-tubules are tubules formed from the same phospholipid bilayeras the surface membrane or sarcolemmaof skeletal or cardiac muscle cells.[1] They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma.[1] Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system.[2] The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. [ 1]
T-tubules are found in both atrialand ventricularcardiac muscle cells (cardiomyocytes), in which they develop in the first few weeks of life.[3] They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.[4] In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discswhere the actin filaments anchor within the cell.[1] T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulumin specific regions referred to as terminal cisternae. The association of the T-tubule with a terminal cistern is known as a diad. [ 5]
In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad. [ 1][6]
Regulators[edit]
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2is encoded by the gene BIN1and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane.[7] Junctophilin-2 is encoded by the gene JPH2and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling.[5] Titin capping protein or Telethonin is encoded by the gene TCAPand helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. [

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 Estimates of the percentage of the ventricular myocyte volume occupied by the t-tubules varies from 3.6% in rat myocytes 2 to 0.8% in mouse myocytes, 7 although this variation probably reflects methodological rather than species differences because there appears to be no clear relationship between species and estimates of percentage cell volume occupied by the t-tubules. Similarly, estimates of the percentage of cell membrane located in the t-tubules vary from 64% (calculated in Bers 11 from data in Soeller and Cannell 2) to 21%, 15 with no apparent species differences. The t-tubules of cardiac muscle have a mean diameter of ≈200 to 300 nm, 13 although within a single rat ventricular myocyte, the diameter of individual tubules can vary from 20 to 450 nm, but with more than half the t-tubules having diameters between 180 and 280 nm. 2 One consequence of this network of narrow tubules is that a rapid change in the composition of the solution around a ventricular myocyte results in a slower change in the composition of the fluid within the t-tubules because of the time required for diffusion into the t-tubular network. In guinea pig myocytes, a rapid change of [Ca 2+] o results in the diffusion of Ca 2+ into the t-tubules at 3 to 16 μm/s, 16 so that the solution change within the t-tubules is delayed by up to 2.3 seconds, and washout of Ca 2+ from the t-tubules occurs with a time constant of up to 1.7 seconds for the deeper regions of the t-tubular system, 16 although these time courses may vary between species, 17 possibly reflecting species differences in t-tubule morphology. Although the diversity of estimates of the extent of the t-tubules within a species makes it impossible to determine whether there may be differences between species, it is tempting to speculate that the extent of the t-tubules varies between species depending on cell size (surface area/volume ratio) and heart rate if the t-tubules are necessary to produce synchronous Ca 2+ release throughout the cell (see Coupling of Ca 2+ Entry and Ca 2+ Release, later) and, hence, synchronous contraction. Although we are unaware of any differences related to cell size, the density of the t-tubular network is greater in the mouse, which has a resting heart rate of 300 to 400 bpm, than in the pig, which has a heart rate of <100 bpm. 1
T-Tubule Development Is Labile
Ventricular myocytes isolated from neonatal hearts show little evidence of t-tubule development, 4,18 and cells kept in culture for 6 days show a progressive decrease of t-tubule density. 19 T-tubule structure has also been reported to change in myocytes from failing hearts (see T-Tubule Development and Morphology in Hypertrophy and Failure). However, the mechanisms underlying the expression and maintenance of the t-tubules are not clear.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research

Myocytes - an overview | ScienceDirect Topics Myocytes
Myocytes
Cardiovascular Research
B. Atrial Myocardium
Cardiovascular and Skeletal Muscle Systems
Cellular and Extracellular Elements of the Heart: Biology and Clinical Relevance
Ventricular Myocytes
Atrial Myocytes
Conduction System
Components of Myocardial Interstitium
Cellular Components of the Myocardial Vasculature
Myocardial Innervation
Cardiomyocyte Ultrastructure
Regional Variation in Structure
Functional Morphology of the Cardiac Myocyte
21.7 Variation in Morphology Among Different Cardiac Myocyte Types
Electrophysiology and Microinjection
Total Myoplasmic [Ca] during Systole
Cardiovascular System
Ventricular Myocytes
Cardiac cells
Myocytes
Positive lusitropy
Negative lusitropy
Organ-Specific Toxicologic Pathology
a. Ventricular Myocytes
Thyroid Hormone Action on the Heart and Cardiovascular System
III T3 effects on myocyte physiology
Recommended publications
 Jamieson and Palade, 1964). Although some reports indicate an absence of T tubules in atrial myocardium (Hibbs and Ferrans, 1969), studies with horseradish peroxidase tracer have identified two populations of atrial cells: one without T tubules and the other possessing T tubules. Atrial myocytes have been reported to have only a single nucleus with large mitochondrial collections at the nuclear poles (Jamieson and Palade, 1964 ). However, unpublished studies with isolated myocytes in one of our laboratories (S.P.B.) show that atrial myocytes have two nuclei, as in ventricular myocytes. Jamieson and Palade (1964) described the ultrastructure of the rat atrium and specifically drew attention to the electron-dense, membrane-bound, atrial-specific granules present not only in rat atrium but in all mammalian atrial myocytes. In the rat heart, atrial granules are larger and more numerous than those in larger mammals. These granules are now recognized to contain a specific natriuretic substance, atrial natriuretic factor, which plays a role in systemic fluid balance (DeBold, 1985; Brenner et al., 1990 ).

Myocytes - an overview | ScienceDirect Topics

Myocytes
Myocytes
Cardiovascular Research
B. Atrial Myocardium
Cardiovascular and Skeletal Muscle Systems
Cellular and Extracellular Elements of the Heart: Biology and Clinical Relevance
Ventricular Myocytes
Atrial Myocytes
Conduction System
Components of Myocardial Interstitium
Cellular Components of the Myocardial Vasculature
Myocardial Innervation
Cardiomyocyte Ultrastructure
Regional Variation in Structure
Functional Morphology of the Cardiac Myocyte
21.7 Variation in Morphology Among Different Cardiac Myocyte Types
Electrophysiology and Microinjection
Total Myoplasmic [Ca] during Systole
Cardiovascular System
Ventricular Myocytes
Cardiac cells
Myocytes
Positive lusitropy
Negative lusitropy
Organ-Specific Toxicologic Pathology
a. Ventricular Myocytes
Thyroid Hormone Action on the Heart and Cardiovascular System
III T3 effects on myocyte physiology
Recommended publications

Jamieson and Palade, 1964). Although some reports indicate an absence of T tubules in atrial myocardium (Hibbs and Ferrans, 1969), studies with horseradish peroxidase tracer have identified two populations of atrial cells: one without T tubules and the other possessing T tubules. Atrial myocytes have been reported to have only a single nucleus with large mitochondrial collections at the nuclear poles (Jamieson and Palade, 1964 ). However, unpublished studies with isolated myocytes in one of our laboratories (S.P.B.) show that atrial myocytes have two nuclei, as in ventricular myocytes. Jamieson and Palade (1964) described the ultrastructure of the rat atrium and specifically drew attention to the electron-dense, membrane-bound, atrial-specific granules present not only in rat atrium but in all mammalian atrial myocytes. In the rat heart, atrial granules are larger and more numerous than those in larger mammals. These granules are now recognized to contain a specific natriuretic substance, atrial natriuretic factor, which plays a role in systemic fluid balance (DeBold, 1985; Brenner et al., 1990 ).

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THIS SET IS OFTEN IN FOLDERS WITH...
Chapter 2
Anatomy Chapter 10
LP 10
Muscle Tissue Practice Exam
 ...
What is the function of acetylcholine in regard to muscle contraction? ...
What are the steps involved with excitation-contraction coupling? ...
When actin and myosin form a connection during muscle contraction, what is that connection called? ...
What is the T-tubule, and what is its function? ...
What are the different ways that muscle gets its ATP, depending on the length of activity? ...
What needs to occur in order for a muscle to relax after contracting? ...
What is the role of connectin in muscle contraction and/or relaxation? ...
What is "treppe?" ...
What is the role of acetylcholinesterase? ...
What are the anatomical components found in a sarcomere?

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...
What is the function of acetylcholine in regard to muscle contraction? ...
What are the steps involved with excitation-contraction coupling? ...
When actin and myosin form a connection during muscle contraction, what is that connection called? ...
What is the T-tubule, and what is its function? ...
What are the different ways that muscle gets its ATP, depending on the length of activity? ...
What needs to occur in order for a muscle to relax after contracting? ...
What is the role of connectin in muscle contraction and/or relaxation? ...
What is "treppe?" ...
What is the role of acetylcholinesterase? ...
What are the anatomical components found in a sarcomere?

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T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases | Skeletal Muscle | Full Text T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
Abstract
Introduction
T-tubule plasticity
Morphological aspects of triad biogenesis
Sarcoplasmic reticulum
Transverse tubule
Molecular mechanisms involved in T-tubule biogenesis and triad formation and maintenance
Table 1 Proteins implicated in triad organization, roles and associated human diseasesa
Caveolin 3
Amphiphysin 2 (BIN1)
Dysferlin
Mitsugumins
Junctophilins
Myotubularin
The RyR-DHPR complex
Conclusion
References
Acknowledgements
Author information
Affiliations
Corresponding author
Additional information
Competing interests
Authors' contributions
Authors’ original submitted files for images
Authors’ original file for figure 1
Authors’ original file for figure 2
Authors’ original file for figure 3
Authors’ original file for figure 4
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 Here, we provide a description of triad structure and plasticity and review the role of proteins that have been linked to T-tubule biogenesis and triad formation and/or maintenance specifically in skeletal muscle: caveolin 3, amphiphysin 2, dysferlin, mitsugumins, junctophilins, myotubularin, ryanodine receptor, and dihydhropyridine Receptor. The importance of these proteins in triad biogenesis and subsequently in muscle contraction is sustained by studies on animal models and by the direct implication of most of these proteins in human myopathies. Introduction
To trigger skeletal muscle contraction, the action potential generated by motor neurons is transmitted through motor nerves to muscle cells. The excitation-contraction (EC) coupling, i.e. signal transmission from the sarcolemma to the actin/myosin apparatus, is mediated by a second messenger, calcium ions. Indeed, muscle fibers contain large internal calcium stores with the ability to quickly release and retrieve calcium (Figure 1, right panel). For a fast and fine-tuning of muscle contraction, these stores are maintained under the control of the action potential, which ensures calcium release simultaneously within the whole interior of the muscle fiber. As myofibers are 50-100 μm in diameter and several millimeters to centimeters long, a highly specialized structure named the triad is necessary to overcome spatial limits in using calcium as secondary messenger, and connect the sarcolemma with the calcium stores. The sarcolemma forms regular invaginations which insert between myofibrils, termed transverse tubules (T-tubules). In skeletal muscle, T-tubules tightly associate with the sarcoplasmic reticulum (SR), in a region called terminal cisternae/junctional SR.

T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases | Skeletal Muscle | Full Text

T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
T-tubule biogenesis and triad formation in skeletal muscle and implication in human diseases
Abstract
Introduction
T-tubule plasticity
Morphological aspects of triad biogenesis
Sarcoplasmic reticulum
Transverse tubule
Molecular mechanisms involved in T-tubule biogenesis and triad formation and maintenance
Table 1 Proteins implicated in triad organization, roles and associated human diseasesa
Caveolin 3
Amphiphysin 2 (BIN1)
Dysferlin
Mitsugumins
Junctophilins
Myotubularin
The RyR-DHPR complex
Conclusion
References
Acknowledgements
Author information
Affiliations
Corresponding author
Additional information
Competing interests
Authors' contributions
Authors’ original submitted files for images
Authors’ original file for figure 1
Authors’ original file for figure 2
Authors’ original file for figure 3
Authors’ original file for figure 4
Rights and permissions
About this article
Cite this article
Share this article
Keywords

Here, we provide a description of triad structure and plasticity and review the role of proteins that have been linked to T-tubule biogenesis and triad formation and/or maintenance specifically in skeletal muscle: caveolin 3, amphiphysin 2, dysferlin, mitsugumins, junctophilins, myotubularin, ryanodine receptor, and dihydhropyridine Receptor. The importance of these proteins in triad biogenesis and subsequently in muscle contraction is sustained by studies on animal models and by the direct implication of most of these proteins in human myopathies. Introduction
To trigger skeletal muscle contraction, the action potential generated by motor neurons is transmitted through motor nerves to muscle cells. The excitation-contraction (EC) coupling, i.e. signal transmission from the sarcolemma to the actin/myosin apparatus, is mediated by a second messenger, calcium ions. Indeed, muscle fibers contain large internal calcium stores with the ability to quickly release and retrieve calcium (Figure 1, right panel). For a fast and fine-tuning of muscle contraction, these stores are maintained under the control of the action potential, which ensures calcium release simultaneously within the whole interior of the muscle fiber. As myofibers are 50-100 μm in diameter and several millimeters to centimeters long, a highly specialized structure named the triad is necessary to overcome spatial limits in using calcium as secondary messenger, and connect the sarcolemma with the calcium stores. The sarcolemma forms regular invaginations which insert between myofibrils, termed transverse tubules (T-tubules). In skeletal muscle, T-tubules tightly associate with the sarcoplasmic reticulum (SR), in a region called terminal cisternae/junctional SR.

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A&P Chapter 10 - Lecture Exam 2 10. 11) After the fusion of myoblasts, the muscle fiber loses its ability  to do what? a) grow
b) lengthen
c) contract
d) go through cell division. e) all of the answer choices
d) go through cell division. 11. 12) Which of the following correctly lists the sequence of structures  that action potentials must move through to excite skeletal muscle contraction? a) sarcolemma, axon of neuron, T tubules
b) T tubules, sarcolemma, myofilament
c) muscle fiber, axon of neuron, myofibrils
d) axon of neuron, sarcolemma, T tubules
e) myofibrils, myofilaments, mitochondria
d) axon of neuron, sarcolemma, T tubules
12. 13) The mitochondria in skeletal muscle fiber are arranged
a) randomly throughout the sarcoplasm. b) in circles around the T-tubules. c) around the nuclei.

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10. 11) After the fusion of myoblasts, the muscle fiber loses its ability  to do what? a) grow
b) lengthen
c) contract
d) go through cell division. e) all of the answer choices
d) go through cell division. 11. 12) Which of the following correctly lists the sequence of structures  that action potentials must move through to excite skeletal muscle contraction? a) sarcolemma, axon of neuron, T tubules
b) T tubules, sarcolemma, myofilament
c) muscle fiber, axon of neuron, myofibrils
d) axon of neuron, sarcolemma, T tubules
e) myofibrils, myofilaments, mitochondria
d) axon of neuron, sarcolemma, T tubules
12. 13) The mitochondria in skeletal muscle fiber are arranged
a) randomly throughout the sarcoplasm. b) in circles around the T-tubules. c) around the nuclei.

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 A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected? A series of proteins that control calcium release. *When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? transverse or T tubules
*T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. *Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm.

A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected? A series of proteins that control calcium release. *When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? transverse or T tubules
*T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. *Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm.

Sarcolemma - Definition and Examples - Biology Online Dictionary Sarcolemma Definition
Sarcolemma
Table of Contents
Sarcolemma Definition
Characteristics of Sarcolemma
Sarcolemma Structure
The Function of the Sarcolemma
What initiates an action potential on a muscle cell?
The Importance of T-tubules and Triads
Dysfunctional Sarcolemma
Biological Importance of Sarcolemma
References:
Quiz
 As the muscle cell membrane, the sarcolemma functions as a barrier between the extracellular and intercellular parts of the muscle fiber cells. It can do this because the membrane is lipid in nature, thereby it separates the fluids of the intracellular and extracellular spaces and only allows water in through aquaporin channels. The membrane contains ion pumps as in other cell membranes in the body, allowing for ion gradients to be created to use up ATP. The T-tubule membrane portion of the sarcolemma is highly plastic and therefore provides stability during muscle contraction. Studies have also shown that T tubules are involved in water balance and cell volume regulation, recovery from muscle fatigue as well as transport of molecules. The T-tubules also have an important role involved in the transmission of action potentials which will be discussed later. The structure and design of the sarcolemma are essential for receiving and conducting stimuli. During the resting state, the sarcolemma keeps the inside of the muscle fiber at a negative potential compared to the extracellular fluid. It pumps out more sodium ions than it takes in potassium ions. Therefore, the sarcoplasm has a higher potassium concentration but a lower sodium concentration than the extracellular space.

Sarcolemma - Definition and Examples - Biology Online Dictionary

Sarcolemma Definition
Sarcolemma
Table of Contents
Sarcolemma Definition
Characteristics of Sarcolemma
Sarcolemma Structure
The Function of the Sarcolemma
What initiates an action potential on a muscle cell?
The Importance of T-tubules and Triads
Dysfunctional Sarcolemma
Biological Importance of Sarcolemma
References:
Quiz

As the muscle cell membrane, the sarcolemma functions as a barrier between the extracellular and intercellular parts of the muscle fiber cells. It can do this because the membrane is lipid in nature, thereby it separates the fluids of the intracellular and extracellular spaces and only allows water in through aquaporin channels. The membrane contains ion pumps as in other cell membranes in the body, allowing for ion gradients to be created to use up ATP. The T-tubule membrane portion of the sarcolemma is highly plastic and therefore provides stability during muscle contraction. Studies have also shown that T tubules are involved in water balance and cell volume regulation, recovery from muscle fatigue as well as transport of molecules. The T-tubules also have an important role involved in the transmission of action potentials which will be discussed later. The structure and design of the sarcolemma are essential for receiving and conducting stimuli. During the resting state, the sarcolemma keeps the inside of the muscle fiber at a negative potential compared to the extracellular fluid. It pumps out more sodium ions than it takes in potassium ions. Therefore, the sarcoplasm has a higher potassium concentration but a lower sodium concentration than the extracellular space.

 Force is controlled by Ca2+ however cardiac muscle is less dependent on the release of Ca2+ from the SR and the mechanism is different (calcium induced calcium release)
3. Cardiac muscle cells depend primarily on oxidative phosphorylation to generate ATP. They are resistant to fatigue and depend on a continuous supply of oxygen
4. Cardiac muscle cells are much shorter than skeletal muscle fibers and are branched. 5. Cardiac muscle cells are joined together by intercalated discs (desmosomes and gap junctions)
Define the mechanical and functional role of the intercalated disc
Desmosomes mechanically adhere cells together
Gap junctions electrically connect cells and allow action potentials of one cell to spread to another. This allows the heart to contract as a unit. Compare and contrast the excitation-contraction coupling in cardiac and skeletal muscle
The organization of the membrane system involved in excitation-contraction coupling is similar to that in skeletal muscle. A few diffferences include sparser sarcoplasmic reticulum, t-tubules positioned near Z lines instead of A-I band junctions, t-tubules are larger in diameter, SR makes junctions with t-tubules, dyads in cardiac muscle vs triads in skeletal muscle. Explain the mechanisms of Ca2+ entry and extrusion from cardiac muscle cells
Action potential initiated by pacemaker cells propagates to the sarcolemma and spreads into the T-tubular membrane.

Force is controlled by Ca2+ however cardiac muscle is less dependent on the release of Ca2+ from the SR and the mechanism is different (calcium induced calcium release)
3. Cardiac muscle cells depend primarily on oxidative phosphorylation to generate ATP. They are resistant to fatigue and depend on a continuous supply of oxygen
4. Cardiac muscle cells are much shorter than skeletal muscle fibers and are branched. 5. Cardiac muscle cells are joined together by intercalated discs (desmosomes and gap junctions)
Define the mechanical and functional role of the intercalated disc
Desmosomes mechanically adhere cells together
Gap junctions electrically connect cells and allow action potentials of one cell to spread to another. This allows the heart to contract as a unit. Compare and contrast the excitation-contraction coupling in cardiac and skeletal muscle
The organization of the membrane system involved in excitation-contraction coupling is similar to that in skeletal muscle. A few diffferences include sparser sarcoplasmic reticulum, t-tubules positioned near Z lines instead of A-I band junctions, t-tubules are larger in diameter, SR makes junctions with t-tubules, dyads in cardiac muscle vs triads in skeletal muscle. Explain the mechanisms of Ca2+ entry and extrusion from cardiac muscle cells
Action potential initiated by pacemaker cells propagates to the sarcolemma and spreads into the T-tubular membrane.

Free Anatomy Flashcards about Ch 9 muscles/tissues Ch 9 muscles/tissues
Question
Question
Ch 9 muscles/tissues
Ch 9 practice exam muscles and muscle tissues
 a change in temperature. What does Aponeurosis refer to? a sheetlike indirect attachment to a skeletal element
What is the oxygen-binding protein found in muscle cells? Myoglobin
Whats the name of the contractile units in skeletal muscles? Myofibrils
What is the site of calcium regulation in the smooth muscle cell called? Calmodulin
One functional unit of skeletal muscle is___: a sarcomere
What is the functional role of T Tubules? to enhance cellular communication during muscle contraction. What is the role of calcium ions in muscle contraction? to bind to regulatory sites on troponin, changing the configuration.

Free Anatomy Flashcards about Ch 9 muscles/tissues

Ch 9 muscles/tissues
Question
Question
Ch 9 muscles/tissues
Ch 9 practice exam muscles and muscle tissues

a change in temperature. What does Aponeurosis refer to? a sheetlike indirect attachment to a skeletal element
What is the oxygen-binding protein found in muscle cells? Myoglobin
Whats the name of the contractile units in skeletal muscles? Myofibrils
What is the site of calcium regulation in the smooth muscle cell called? Calmodulin
One functional unit of skeletal muscle is___: a sarcomere
What is the functional role of T Tubules? to enhance cellular communication during muscle contraction. What is the role of calcium ions in muscle contraction? to bind to regulatory sites on troponin, changing the configuration.

Cardiac T-Tubule Microanatomy and Function | Physiological Reviews Cardiac T-Tubule Microanatomy and Function
Cardiac T-Tubule Microanatomy and Function
Abstract
I. INTRODUCTION
II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
B. Gross Morphology and Geometry
C. Membrane Ultrastructure and Microdomains
1. cBIN1 microfolds: microdomains supporting LTCC-RyR dyads
2. Caveoli (caveolae): β-AR/LTCC signaling hubs
3. Ankyrin B microdomains: NCX/NKA/InsP 3 macromolecular complex
D. Peri-Membrane Cytoskeleton Scaffolds at Cardiac T-Tubules
1. Actin filaments, tropomyosin, and N-WASP
2. Costamere complex and t-tubule membrane-associated scaffolds
3. Myofilament structural proteins
E. Variation in Cardiac T-Tubule Geometry
III. TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
1. Ca 2+ handling proteins
2. Na + handling proteins
3. K + handling proteins
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
1. LTCC trafficking and clustering to dyads through BIN1
2. RyR recruitment to dyads through BIN1
3. Junctophilin-2 in t-tubule-jSR junctional membrane complex formation
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments
 TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments
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Abstract
Unique to striated muscle cells, transverse tubules (t-tubules) are membrane organelles that consist of sarcolemma penetrating into the myocyte interior, forming a highly branched and interconnected network. Mature t-tubule networks are found in mammalian ventricular cardiomyocytes, with the transverse components of t-tubules occurring near sarcomeric z-discs. Cardiac t-tubules contain membrane microdomains enriched with ion channels and signaling molecules. The microdomains serve as key signaling hubs in regulation of cardiomyocyte function. Dyad microdomains formed at the junctional contact between t-tubule membrane and neighboring sarcoplasmic reticulum are critical in calcium signaling and excitation-contraction coupling necessary for beat-to-beat heart contraction. In this review, we provide an overview of the current knowledge in gross morphology and structure, membrane and protein composition, and function of the cardiac t-tubule network. We also review in detail current knowledge on the formation of functional membrane subdomains within t-tubules, with a particular focus on the cardiac dyad microdomain.

TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments
PDF (4 MB)
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Abstract
Unique to striated muscle cells, transverse tubules (t-tubules) are membrane organelles that consist of sarcolemma penetrating into the myocyte interior, forming a highly branched and interconnected network. Mature t-tubule networks are found in mammalian ventricular cardiomyocytes, with the transverse components of t-tubules occurring near sarcomeric z-discs. Cardiac t-tubules contain membrane microdomains enriched with ion channels and signaling molecules. The microdomains serve as key signaling hubs in regulation of cardiomyocyte function. Dyad microdomains formed at the junctional contact between t-tubule membrane and neighboring sarcoplasmic reticulum are critical in calcium signaling and excitation-contraction coupling necessary for beat-to-beat heart contraction. In this review, we provide an overview of the current knowledge in gross morphology and structure, membrane and protein composition, and function of the cardiac t-tubule network. We also review in detail current knowledge on the formation of functional membrane subdomains within t-tubules, with a particular focus on the cardiac dyad microdomain.

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A&P Lecture Ch. 8,9,11
Module 3: Section 9.04
Mastering A&P Chapter 3 - Cells: The Liv…
Anatomy and Physiology Chapter 9 Part 1
 B) Potassium leak channels. C) A series of proteins that control calcium release. D) Voltage-gated sodium channels. A series of proteins that control calcium release. ( When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? A) Sarcoplasmic reticulum
B) motor endplates
C) terminal cisternae
D) transverse or T tubules
transverse or t-tubules (T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior.) Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? A) sodium ions
B) calcium ions
C) Acetylcholine
D) Action potentials
Calcium ions (Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm.

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Muscles and Muscle tissue
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A&P Lecture Ch. 8,9,11
Module 3: Section 9.04
Mastering A&P Chapter 3 - Cells: The Liv…
Anatomy and Physiology Chapter 9 Part 1

B) Potassium leak channels. C) A series of proteins that control calcium release. D) Voltage-gated sodium channels. A series of proteins that control calcium release. ( When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? A) Sarcoplasmic reticulum
B) motor endplates
C) terminal cisternae
D) transverse or T tubules
transverse or t-tubules (T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior.) Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? A) sodium ions
B) calcium ions
C) Acetylcholine
D) Action potentials
Calcium ions (Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm.

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discs where the actin filaments anchor within the cell. T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulum in specific regions referred to as terminal cisternae. The association of the T-tubule with a terminal cistern is known as a diad. In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad. Regulators
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2 is encoded by the gene BIN1 and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane. Junctophilin-2 is encoded by the gene JPH2 and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling. Titin capping protein known as telethonin is encoded by the TCAP gene and helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. Function
Excitation-contraction coupling
See also:

T-tubule - Wikipedia

T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References

In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discs where the actin filaments anchor within the cell. T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulum in specific regions referred to as terminal cisternae. The association of the T-tubule with a terminal cistern is known as a diad. In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad. Regulators
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2 is encoded by the gene BIN1 and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane. Junctophilin-2 is encoded by the gene JPH2 and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling. Titin capping protein known as telethonin is encoded by the TCAP gene and helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. Function
Excitation-contraction coupling
See also:

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discs where the actin filaments anchor within the cell. T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulum in specific regions referred to as terminal cisternae. The association of the T-tubule with a terminal cistern is known as a diad. In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad. Regulators
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2 is encoded by the gene BIN1 and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane. Junctophilin-2 is encoded by the gene JPH2 and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling. Titin capping protein or Telethonin is encoded by the gene TCAP and helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. Function
Excitation-contraction coupling
See also:

T-tubule - Wikipedia

In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discs where the actin filaments anchor within the cell. T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulum in specific regions referred to as terminal cisternae. The association of the T-tubule with a terminal cistern is known as a diad. In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad. Regulators
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2 is encoded by the gene BIN1 and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane. Junctophilin-2 is encoded by the gene JPH2 and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling. Titin capping protein or Telethonin is encoded by the gene TCAP and helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. Function
Excitation-contraction coupling
See also:

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Terms in this set (70)
 increased excitability of the muscle fibers at the site of injection. increased levels of ACh in the synaptic cleft. muscle paralysis at the site of injection. muscle paralysis at the site of injection. What are the components of a triad? One actin and one myosin
Two terminal cisternae of the SR and one calcium ion
Two thin filaments and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Excitation-contraction coupling results in an increase of calcium ion concentration: in the cytosol of the muscle fiber. in the sarcoplasmic reticulum. in the T-tubules. in the synaptic cleft.

increased excitability of the muscle fibers at the site of injection. increased levels of ACh in the synaptic cleft. muscle paralysis at the site of injection. muscle paralysis at the site of injection. What are the components of a triad? One actin and one myosin
Two terminal cisternae of the SR and one calcium ion
Two thin filaments and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Excitation-contraction coupling results in an increase of calcium ion concentration: in the cytosol of the muscle fiber. in the sarcoplasmic reticulum. in the T-tubules. in the synaptic cleft.

Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum | Neupsy Key Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum
Muscle Membrane, T Tubules, and Sarcoplasmic Reticulum
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 Free sarcoplasmic reticulum constitutes the remainder of the intrafiber sarcoplasmic reticulum membrane system. It is not associated with the T tubule system and functions in Ca 2+ reuptake into the sarcoplasmic reticulum. It has a large number of Ca 2+ adenosine triphosphatase (ATPase) pumps on its surface that function in the energy-dependent reuptake of sarcoplasmic Ca 2+ and therefore plays a role in muscle relaxation rather than excitation and contraction. A motor nerve action potential propagates down the motor nerve axon to the nerve terminal, causing release of acetylcholine (ACh) into the synaptic cleft of the neuromuscular junction. After binding of acetylcholine to the postsynaptic muscle membrane acetylcholine receptor (AChR), there is generation of an end-plate potential. Suprathreshold end-plate potentials generate muscle fiber action potentials. These propagate along the sarcolemma, depolarizing the muscle membrane sequentially as it travels along the membrane. The action potential continues down the T tubules. Depolarization of the T tubule membrane activates the voltage-gated Ca 2+ channel, thus activating the ryanodine receptor, releasing large amounts of Ca 2+ from the sarcoplasmic reticulum into the sarcoplasm. This leads to cross-bridge formation between thin and thick filaments, activation of the cross-bridge cycle, sliding of the thick and thin filaments past one another, sarcomere shortening, and eventually muscle contraction.

Free sarcoplasmic reticulum constitutes the remainder of the intrafiber sarcoplasmic reticulum membrane system. It is not associated with the T tubule system and functions in Ca 2+ reuptake into the sarcoplasmic reticulum. It has a large number of Ca 2+ adenosine triphosphatase (ATPase) pumps on its surface that function in the energy-dependent reuptake of sarcoplasmic Ca 2+ and therefore plays a role in muscle relaxation rather than excitation and contraction. A motor nerve action potential propagates down the motor nerve axon to the nerve terminal, causing release of acetylcholine (ACh) into the synaptic cleft of the neuromuscular junction. After binding of acetylcholine to the postsynaptic muscle membrane acetylcholine receptor (AChR), there is generation of an end-plate potential. Suprathreshold end-plate potentials generate muscle fiber action potentials. These propagate along the sarcolemma, depolarizing the muscle membrane sequentially as it travels along the membrane. The action potential continues down the T tubules. Depolarization of the T tubule membrane activates the voltage-gated Ca 2+ channel, thus activating the ryanodine receptor, releasing large amounts of Ca 2+ from the sarcoplasmic reticulum into the sarcoplasm. This leads to cross-bridge formation between thin and thick filaments, activation of the cross-bridge cycle, sliding of the thick and thin filaments past one another, sarcomere shortening, and eventually muscle contraction.

Difference Between Endomysium and Sarcolemma | Compare the Difference Between Similar Terms Difference Between Endomysium and Sarcolemma
Difference Between Endomysium and Sarcolemma
CONTENTS
What is Endomysium?
What is Sarcolemma?
What are the Similarities Between Endomysium and Sarcolemma?
What is the Difference Between Endomysium and Sarcolemma?
Summary – Endomysium vs Sarcolemma
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 The transverse tubules are also referred to as T tubules. The terminal cisternae are formed on either side of the t tubules. When the t tubule is surrounded by two cisterns, it is referred to as a triad. Figure 02: Sarcolemma
The main function of the sarcolemma, in terms of muscle contraction, is to facilitate the permeability of Calcium ions required for the contraction process. Calcium ions are transported across the sarcolemma via ion channels and are transported into the cytoplasm of the muscle cell (sarcoplasm) via the transverse tubules. And, this will initiate the muscle action potential to bring about muscle contraction. Sarcolemma also contains various signal receiving receptors, which are required in controlling the muscle cell activities. What are the Similarities Between Endomysium and Sarcolemma? Endomysium and sarcolemma are found in muscle tissue.

Difference Between Endomysium and Sarcolemma | Compare the Difference Between Similar Terms

Difference Between Endomysium and Sarcolemma
Difference Between Endomysium and Sarcolemma
CONTENTS
What is Endomysium?
What is Sarcolemma?
What are the Similarities Between Endomysium and Sarcolemma?
What is the Difference Between Endomysium and Sarcolemma?
Summary – Endomysium vs Sarcolemma
Reference:
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About the Author: Samanthi
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The transverse tubules are also referred to as T tubules. The terminal cisternae are formed on either side of the t tubules. When the t tubule is surrounded by two cisterns, it is referred to as a triad. Figure 02: Sarcolemma
The main function of the sarcolemma, in terms of muscle contraction, is to facilitate the permeability of Calcium ions required for the contraction process. Calcium ions are transported across the sarcolemma via ion channels and are transported into the cytoplasm of the muscle cell (sarcoplasm) via the transverse tubules. And, this will initiate the muscle action potential to bring about muscle contraction. Sarcolemma also contains various signal receiving receptors, which are required in controlling the muscle cell activities. What are the Similarities Between Endomysium and Sarcolemma? Endomysium and sarcolemma are found in muscle tissue.

 3 K+
2 K+; 3 Na+
3 Na+; 2 K+
What are the components of a triad? One actin and one myosin
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Two thin filaments and one T-tubule
Two terminal cisternae of the SR and one calcium ion
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Excitation-contraction coupling results in an increase of calcium ion concentration: in the cytosol of the muscle fiber. in the T-tubules. in the synaptic cleft. in the sarcoplasmic reticulum. in the cytosol of the muscle fiber. Predict the effect of Tetrodotoxin, a powerful blocker of voltage-gated sodium ion channels:

3 K+
2 K+; 3 Na+
3 Na+; 2 K+
What are the components of a triad? One actin and one myosin
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Two thin filaments and one T-tubule
Two terminal cisternae of the SR and one calcium ion
Two terminal cisternae of the sarcoplasma reticulum (SR) and one T-tubule
Excitation-contraction coupling results in an increase of calcium ion concentration: in the cytosol of the muscle fiber. in the T-tubules. in the synaptic cleft. in the sarcoplasmic reticulum. in the cytosol of the muscle fiber. Predict the effect of Tetrodotoxin, a powerful blocker of voltage-gated sodium ion channels:

Convoluted - definition of convoluted by The Free Dictionary convoluted
convoluted
con·vo·lut·ed
convoluted
ˈconvoˌlutedly adv
ˈconvoˌlutedness n
con•vo•lut•ed
con′vo•lut`ed•ly, adv.
con′vo•lut`ed•ness, n.
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Cardiac T-Tubule Microanatomy and Function | Physiological Reviews Cardiac T-Tubule Microanatomy and Function
Cardiac T-Tubule Microanatomy and Function
Abstract
I. INTRODUCTION
II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
B. Gross Morphology and Geometry
C. Membrane Ultrastructure and Microdomains
1. cBIN1 microfolds: microdomains supporting LTCC-RyR dyads
2. Caveoli (caveolae): β-AR/LTCC signaling hubs
3. Ankyrin B microdomains: NCX/NKA/InsP 3 macromolecular complex
D. Peri-Membrane Cytoskeleton Scaffolds at Cardiac T-Tubules
1. Actin filaments, tropomyosin, and N-WASP
2. Costamere complex and t-tubule membrane-associated scaffolds
3. Myofilament structural proteins
E. Variation in Cardiac T-Tubule Geometry
III. TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
1. Ca 2+ handling proteins
2. Na + handling proteins
3. K + handling proteins
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
1. LTCC trafficking and clustering to dyads through BIN1
2. RyR recruitment to dyads through BIN1
3. Junctophilin-2 in t-tubule-jSR junctional membrane complex formation
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments
 Lastly, we discuss the dynamic nature of t-tubules including membrane turnover, trafficking of transmembrane proteins, and the life cycles of membrane subdomains such as the cardiac BIN1-microdomain, as well as t-tubule remodeling and alteration in diseased hearts. Understanding cardiac t-tubule biology in normal and failing hearts is providing novel diagnostic and therapeutic opportunities to better treat patients with failing hearts. I. INTRODUCTION
Cardiac transverse tubules (t-tubules) are highly branched invaginations of cardiomyocyte sarcolemma that are rich in ion channels important for excitation-contraction (EC) coupling, maintenance of resting membrane potential, action potential initiation and regulation, and signaling transduction. Specific to striated muscle cells, t-tubules are invaginations of the sarcolemma, penetrating into the intracellular space of myocytes. These tubular invaginations form a complex network with transverse tubules that are interconnected within the cytoplasm by longitudinal tubules. The transverse tubules occur around myofilaments, anchoring to sarcomeric z-discs through costameres. The phospholipid-rich t-tubule lipid bilayers are shaped and maintained by membrane scaffolding proteins and intracellular cytoskeleton, as well as surrounding extracellular matrix. T-tubule membrane contains microdomains that compartmentalize transmembrane ion handling proteins and signaling molecules. Together, t-tubules are effective organelles that serve as a centralized signaling hub controlling cardiac contractile function and electrophysiology. The most recognized function of t-tubules is regulation of cardiac EC coupling by concentrating voltage-gated L-type calcium channels (LTCCs) and positioning them in close proximity to calcium sense and release channels, ryanodine receptors (RyRs), at the junctional membrane of sarcoplasmic reticulum (jSR).

Cardiac T-Tubule Microanatomy and Function | Physiological Reviews Cardiac T-Tubule Microanatomy and Function
Cardiac T-Tubule Microanatomy and Function
Abstract
I. INTRODUCTION
II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
B. Gross Morphology and Geometry
C. Membrane Ultrastructure and Microdomains
1. cBIN1 microfolds: microdomains supporting LTCC-RyR dyads
2. Caveoli (caveolae): β-AR/LTCC signaling hubs
3. Ankyrin B microdomains: NCX/NKA/InsP 3 macromolecular complex
D. Peri-Membrane Cytoskeleton Scaffolds at Cardiac T-Tubules
1. Actin filaments, tropomyosin, and N-WASP
2. Costamere complex and t-tubule membrane-associated scaffolds
3. Myofilament structural proteins
E. Variation in Cardiac T-Tubule Geometry
III. TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
1. Ca 2+ handling proteins
2. Na + handling proteins
3. K + handling proteins
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
1. LTCC trafficking and clustering to dyads through BIN1
2. RyR recruitment to dyads through BIN1
3. Junctophilin-2 in t-tubule-jSR junctional membrane complex formation
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments
 Cardiac t-tubules contain membrane microdomains enriched with ion channels and signaling molecules. The microdomains serve as key signaling hubs in regulation of cardiomyocyte function. Dyad microdomains formed at the junctional contact between t-tubule membrane and neighboring sarcoplasmic reticulum are critical in calcium signaling and excitation-contraction coupling necessary for beat-to-beat heart contraction. In this review, we provide an overview of the current knowledge in gross morphology and structure, membrane and protein composition, and function of the cardiac t-tubule network. We also review in detail current knowledge on the formation of functional membrane subdomains within t-tubules, with a particular focus on the cardiac dyad microdomain. Lastly, we discuss the dynamic nature of t-tubules including membrane turnover, trafficking of transmembrane proteins, and the life cycles of membrane subdomains such as the cardiac BIN1-microdomain, as well as t-tubule remodeling and alteration in diseased hearts. Understanding cardiac t-tubule biology in normal and failing hearts is providing novel diagnostic and therapeutic opportunities to better treat patients with failing hearts. I. INTRODUCTION
Cardiac transverse tubules (t-tubules) are highly branched invaginations of cardiomyocyte sarcolemma that are rich in ion channels important for excitation-contraction (EC) coupling, maintenance of resting membrane potential, action potential initiation and regulation, and signaling transduction. Specific to striated muscle cells, t-tubules are invaginations of the sarcolemma, penetrating into the intracellular space of myocytes. These tubular invaginations form a complex network with transverse tubules that are interconnected within the cytoplasm by longitudinal tubules.

Cardiac t-tubules contain membrane microdomains enriched with ion channels and signaling molecules. The microdomains serve as key signaling hubs in regulation of cardiomyocyte function. Dyad microdomains formed at the junctional contact between t-tubule membrane and neighboring sarcoplasmic reticulum are critical in calcium signaling and excitation-contraction coupling necessary for beat-to-beat heart contraction. In this review, we provide an overview of the current knowledge in gross morphology and structure, membrane and protein composition, and function of the cardiac t-tubule network. We also review in detail current knowledge on the formation of functional membrane subdomains within t-tubules, with a particular focus on the cardiac dyad microdomain. Lastly, we discuss the dynamic nature of t-tubules including membrane turnover, trafficking of transmembrane proteins, and the life cycles of membrane subdomains such as the cardiac BIN1-microdomain, as well as t-tubule remodeling and alteration in diseased hearts. Understanding cardiac t-tubule biology in normal and failing hearts is providing novel diagnostic and therapeutic opportunities to better treat patients with failing hearts. I. INTRODUCTION
Cardiac transverse tubules (t-tubules) are highly branched invaginations of cardiomyocyte sarcolemma that are rich in ion channels important for excitation-contraction (EC) coupling, maintenance of resting membrane potential, action potential initiation and regulation, and signaling transduction. Specific to striated muscle cells, t-tubules are invaginations of the sarcolemma, penetrating into the intracellular space of myocytes. These tubular invaginations form a complex network with transverse tubules that are interconnected within the cytoplasm by longitudinal tubules.

 Cardiac muscle cells are joined together by intercalated discs (desmosomes and gap junctions)
Define the mechanical and functional role of the intercalated disc
Desmosomes mechanically adhere cells together
Gap junctions electrically connect cells and allow action potentials of one cell to spread to another. This allows the heart to contract as a unit. Compare and contrast the excitation-contraction coupling in cardiac and skeletal muscle
The organization of the membrane system involved in excitation-contraction coupling is similar to that in skeletal muscle. A few diffferences include sparser sarcoplasmic reticulum, t-tubules positioned near Z lines instead of A-I band junctions, t-tubules are larger in diameter, SR makes junctions with t-tubules, dyads in cardiac muscle vs triads in skeletal muscle. Explain the mechanisms of Ca2+ entry and extrusion from cardiac muscle cells
Action potential initiated by pacemaker cells propagates to the sarcolemma and spreads into the T-tubular membrane. Voltage-dependent L-type Ca2+ channels open. This causes Ca2+ induced Ca2+ release from the SR through the ryanodine receptors. This release of Ca2+ from the SR causes cytoplasmic Ca2+ levels to rise. After contraction, Ca2+ is pumped back into the SR via Ca2+ pumps. Ca2+ is pumped back into the extracellular space by the Na+/Ca2+ exchanger
Explain why cardiac muscle cannot be tetanized
Cardiac muscle cannot produce a second action potential until its contraction is almost complete.

Cardiac muscle cells are joined together by intercalated discs (desmosomes and gap junctions)
Define the mechanical and functional role of the intercalated disc
Desmosomes mechanically adhere cells together
Gap junctions electrically connect cells and allow action potentials of one cell to spread to another. This allows the heart to contract as a unit. Compare and contrast the excitation-contraction coupling in cardiac and skeletal muscle
The organization of the membrane system involved in excitation-contraction coupling is similar to that in skeletal muscle. A few diffferences include sparser sarcoplasmic reticulum, t-tubules positioned near Z lines instead of A-I band junctions, t-tubules are larger in diameter, SR makes junctions with t-tubules, dyads in cardiac muscle vs triads in skeletal muscle. Explain the mechanisms of Ca2+ entry and extrusion from cardiac muscle cells
Action potential initiated by pacemaker cells propagates to the sarcolemma and spreads into the T-tubular membrane. Voltage-dependent L-type Ca2+ channels open. This causes Ca2+ induced Ca2+ release from the SR through the ryanodine receptors. This release of Ca2+ from the SR causes cytoplasmic Ca2+ levels to rise. After contraction, Ca2+ is pumped back into the SR via Ca2+ pumps. Ca2+ is pumped back into the extracellular space by the Na+/Ca2+ exchanger
Explain why cardiac muscle cannot be tetanized
Cardiac muscle cannot produce a second action potential until its contraction is almost complete.

Mastering A&P Chapter 9 - Muscle and Muscle Tissue Diagram | Quizlet Mastering A&P Chapter 9 - Muscle and Muscle Tissue
Mastering A&P Chapter 9 - Muscle and Muscle Tissue
STUDY
PLAY
Terms in this set (104)
 Voltage-gated sodium channels. Myosin cross-bridge binding sites. Potassium leak channels. A series of proteins that control calcium release. Yes! When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? motor endplates
terminal cisternae
sarcoplasmic reticulum
transverse or T tubules
Transverse or T tubules
T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions.

Mastering A&P Chapter 9 - Muscle and Muscle Tissue Diagram | Quizlet

Mastering A&P Chapter 9 - Muscle and Muscle Tissue
Mastering A&P Chapter 9 - Muscle and Muscle Tissue
STUDY
PLAY
Terms in this set (104)

Voltage-gated sodium channels. Myosin cross-bridge binding sites. Potassium leak channels. A series of proteins that control calcium release. Yes! When action potentials propagate along T-tubules, a voltage-sensitive protein changes shape and triggers a different protein to open it's channels, resulting in the release of calcium from the terminal cisternae. What is name given to the regularly spaced infoldings of the sarcolemma? motor endplates
terminal cisternae
sarcoplasmic reticulum
transverse or T tubules
Transverse or T tubules
T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior. Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions.

The Renal Tubule: Definition, Function & Terms - Video & Lesson Transcript | Study.com The Renal Tubule: Definition, Function & Terms
The Renal Tubule: Definition, Function & Terms
The Ultrafiltrate in the Renal Tubule
Proximal Convoluted Tubule
The Loop of Henle
Distal Convoluted Tubule and Connecting Tubule
The Role of PTH in the Regulation of Calcium
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The Renal Tubule: Definition, Function & Terms
Related Study Materials
 This difference in functionality is what establishes the kidney's medullary osmotic gradient for maximal conservation of water. Distal Convoluted Tubule and Connecting Tubule
Once the filtrate passes through the thick ascending limb of Henle, it enters the distal convoluted tubule, which is a duct of the renal tubule located in the kidney's cortex that reabsorbs calcium, sodium, and chloride and regulates the pH of urine by secreting protons and absorbing bicarbonate. The reason this is called the distal, as opposed to proximal, convoluted tubule is because it is the segment farthest away in terms of position and connection to the renal corpuscle. The distal convoluted tubule will then connect to a section called the connecting tubule, which will do many of the same things as the distal convoluted tubule, but it is not, however, considered to be a part of the renal tubule. The Role of PTH in the Regulation of Calcium
It's important to know that a hormone in your body, called parathyroid hormone, or PTH for short, plays a role in the distal and proximal convoluted tubules. Recall that the majority of calcium is reabsorbed, through passive means, in the proximal convoluted tubule. This is the case under normal conditions. However, if PTH is secreted in response to low levels of calcium in the blood, then the proximal convoluted tubule will not be allowed to reabsorb calcium. Instead, the majority of calcium will be reabsorbed actively in the distal convoluted tubule and connecting segment as well as part of the loop of Henle. In addition, PTH will prevent the proximal tubule from reabsorbing phosphate, causing a net excretion of phosphate out of the body via urine.

The Renal Tubule: Definition, Function & Terms - Video & Lesson Transcript | Study.com

The Renal Tubule: Definition, Function & Terms
The Renal Tubule: Definition, Function & Terms
The Ultrafiltrate in the Renal Tubule
Proximal Convoluted Tubule
The Loop of Henle
Distal Convoluted Tubule and Connecting Tubule
The Role of PTH in the Regulation of Calcium
Register to view this lesson
Are you a student or a teacher?
The Renal Tubule: Definition, Function & Terms
Related Study Materials

This difference in functionality is what establishes the kidney's medullary osmotic gradient for maximal conservation of water. Distal Convoluted Tubule and Connecting Tubule
Once the filtrate passes through the thick ascending limb of Henle, it enters the distal convoluted tubule, which is a duct of the renal tubule located in the kidney's cortex that reabsorbs calcium, sodium, and chloride and regulates the pH of urine by secreting protons and absorbing bicarbonate. The reason this is called the distal, as opposed to proximal, convoluted tubule is because it is the segment farthest away in terms of position and connection to the renal corpuscle. The distal convoluted tubule will then connect to a section called the connecting tubule, which will do many of the same things as the distal convoluted tubule, but it is not, however, considered to be a part of the renal tubule. The Role of PTH in the Regulation of Calcium
It's important to know that a hormone in your body, called parathyroid hormone, or PTH for short, plays a role in the distal and proximal convoluted tubules. Recall that the majority of calcium is reabsorbed, through passive means, in the proximal convoluted tubule. This is the case under normal conditions. However, if PTH is secreted in response to low levels of calcium in the blood, then the proximal convoluted tubule will not be allowed to reabsorb calcium. Instead, the majority of calcium will be reabsorbed actively in the distal convoluted tubule and connecting segment as well as part of the loop of Henle. In addition, PTH will prevent the proximal tubule from reabsorbing phosphate, causing a net excretion of phosphate out of the body via urine.

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 Bar=5 μm. Reprinted from Soeller C, Cannell MB. Examination of the transverse tubular system in living cardiac rat myocytes by 2-photon microscopy and digital image–processing techniques. Circ Res. 1999;84:266–275, by permission of the American Heart Association ©1999. Estimates of the percentage of the ventricular myocyte volume occupied by the t-tubules varies from 3.6% in rat myocytes 2 to 0.8% in mouse myocytes, 7 although this variation probably reflects methodological rather than species differences because there appears to be no clear relationship between species and estimates of percentage cell volume occupied by the t-tubules. Similarly, estimates of the percentage of cell membrane located in the t-tubules vary from 64% (calculated in Bers 11 from data in Soeller and Cannell 2) to 21%, 15 with no apparent species differences. The t-tubules of cardiac muscle have a mean diameter of ≈200 to 300 nm, 13 although within a single rat ventricular myocyte, the diameter of individual tubules can vary from 20 to 450 nm, but with more than half the t-tubules having diameters between 180 and 280 nm. 2 One consequence of this network of narrow tubules is that a rapid change in the composition of the solution around a ventricular myocyte results in a slower change in the composition of the fluid within the t-tubules because of the time required for diffusion into the t-tubular network. In guinea pig myocytes, a rapid change of [Ca 2+] o results in the diffusion of Ca 2+ into the t-tubules at 3 to 16 μm/s, 16 so that the solution change within the t-tubules is delayed by up to 2.3 seconds, and washout of Ca 2+ from the t-tubules occurs with a time constant of up to 1.7 seconds for the deeper regions of the t-tubular system, 16 although these time courses may vary between species, 17 possibly reflecting species differences in t-tubule morphology.

Bar=5 μm. Reprinted from Soeller C, Cannell MB. Examination of the transverse tubular system in living cardiac rat myocytes by 2-photon microscopy and digital image–processing techniques. Circ Res. 1999;84:266–275, by permission of the American Heart Association ©1999. Estimates of the percentage of the ventricular myocyte volume occupied by the t-tubules varies from 3.6% in rat myocytes 2 to 0.8% in mouse myocytes, 7 although this variation probably reflects methodological rather than species differences because there appears to be no clear relationship between species and estimates of percentage cell volume occupied by the t-tubules. Similarly, estimates of the percentage of cell membrane located in the t-tubules vary from 64% (calculated in Bers 11 from data in Soeller and Cannell 2) to 21%, 15 with no apparent species differences. The t-tubules of cardiac muscle have a mean diameter of ≈200 to 300 nm, 13 although within a single rat ventricular myocyte, the diameter of individual tubules can vary from 20 to 450 nm, but with more than half the t-tubules having diameters between 180 and 280 nm. 2 One consequence of this network of narrow tubules is that a rapid change in the composition of the solution around a ventricular myocyte results in a slower change in the composition of the fluid within the t-tubules because of the time required for diffusion into the t-tubular network. In guinea pig myocytes, a rapid change of [Ca 2+] o results in the diffusion of Ca 2+ into the t-tubules at 3 to 16 μm/s, 16 so that the solution change within the t-tubules is delayed by up to 2.3 seconds, and washout of Ca 2+ from the t-tubules occurs with a time constant of up to 1.7 seconds for the deeper regions of the t-tubular system, 16 although these time courses may vary between species, 17 possibly reflecting species differences in t-tubule morphology.

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system. The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. T-tubules are found in both atrial and ventricular cardiac muscle cells ( cardiomyocytes ), in which they develop in the first few weeks of life. They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals. In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discs where the actin filaments anchor within the cell. T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulum in specific regions referred to as terminal cisternae. The association of the T-tubule with a terminal cistern is known as a diad. In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad.

T-tubule - Wikipedia

Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system. The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. T-tubules are found in both atrial and ventricular cardiac muscle cells ( cardiomyocytes ), in which they develop in the first few weeks of life. They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals. In cardiac muscle cells, T-tubules are between 20 and 450 nanometers in diameter and are usually located in regions called Z-discs where the actin filaments anchor within the cell. T-tubules within the heart are closely associated with the intracellular calcium store known as the sarcoplasmic reticulum in specific regions referred to as terminal cisternae. The association of the T-tubule with a terminal cistern is known as a diad. In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad.

T-tubule - Wikipedia

Cardiac T-Tubule Microanatomy and Function | Physiological Reviews Cardiac T-Tubule Microanatomy and Function
Cardiac T-Tubule Microanatomy and Function
Abstract
I. INTRODUCTION
II. CARDIAC T-TUBULE STRUCTURE
A. History of T-Tubule Structure-Related Research
B. Gross Morphology and Geometry
C. Membrane Ultrastructure and Microdomains
1. cBIN1 microfolds: microdomains supporting LTCC-RyR dyads
2. Caveoli (caveolae): β-AR/LTCC signaling hubs
3. Ankyrin B microdomains: NCX/NKA/InsP 3 macromolecular complex
D. Peri-Membrane Cytoskeleton Scaffolds at Cardiac T-Tubules
1. Actin filaments, tropomyosin, and N-WASP
2. Costamere complex and t-tubule membrane-associated scaffolds
3. Myofilament structural proteins
E. Variation in Cardiac T-Tubule Geometry
III. TRANSMEMBRANE PROTEINS AT CARDIAC T-TUBULES
A. Ion Handling Proteins (Channels/Transporters/Pumps)
1. Ca 2+ handling proteins
2. Na + handling proteins
3. K + handling proteins
B. Signaling Molecules at Cardiac T-Tubules
IV. FUNCTION OF CARDIAC T-TUBULES
A. Dyad and EC Coupling
1. LTCC trafficking and clustering to dyads through BIN1
2. RyR recruitment to dyads through BIN1
3. Junctophilin-2 in t-tubule-jSR junctional membrane complex formation
B. Ion Diffusion and Membrane Excitability
C. Other Microdomain-Related Functions
V. LIFE CYCLE OF CARDIAC T-TUBULES
A. Membrane Biogenesis, Maintenance, and Turnover
B. Ion Channel Trafficking and Half-Life
VI. ALTERATION OF T-TUBULE STRUCTURE AND FUNCTION IN HEART FAILURE
VII. CONCLUSIONS
GRANTS
DISCLOSURES
Acknowledgments
 The closely approximated LTCCs and RyRs form calcium releasing units, dyads, where calcium transients are initiated following each beat-to-beat action potential. With recent advances in high-resolution imaging technologies, detailed t-tubule microdomain structural organization and newly recognized functions are starting to emerge. For instance, the t-tubular invagination is not smooth, but consists of extensive membrane microfolds sculpted by a cardiac isoform of a BAR domain containing protein bridging integrator 1 (BIN1 or amphiphysin 2) ( 91 ). Cardiac BIN1 (cBIN1) organized membrane microfolds generate diffusion barriers which slow t-tubule-associated extracellular ionic diffusion, preserving electrical stability of myocytes during tachycardia-related fluctuations of ionic concentrations in the local extracellular and possibly intracellular environment ( 91 ). In addition, cBIN1-microfolds also organize local microdomains for efficient and dynamic regulation of cardiac dyad function, regulating EC coupling ( 66, 93, 94 ). Cardiac t-tubules are also substantially remodeled during heart failure ( 38, 52, 89, 97, 98, 108, 130 - 134, 180, 202, 207, 208, 220, 224, 230 ). In addition to the observed loss and gross diminishment of the t-tubule network, protein components at t-tubules including ion channels and signaling molecules are reported to be either reduced at the t-tubule surface or redistributed elsewhere to non-t-tubule sarcolemma ( 20, 93, 134 ). Loss of complex t-tubules in heart failure not only causes impaired contractile function due to disrupted dyads and the resultant EC uncoupling, but also alters local concentration gradients and increases susceptibility to ventricular arrhythmia ( 66, 85, 91, 157, 163, 179, 181, 213 ). The molecular and cellular mechanisms of t-tubule remodeling in failing cardiomyocytes, in particular the alterations in t-tubule membrane ultrastructure and subdomains, is an active area of interest among cardiac biologists. This review summarizes and cites the current knowledge of cardiac t-tubule morphology, structure, components, and physiological functions, with emphasis on the organization and function of microdomains within t-tubules.

Difference Between Sarcolemma and Sarcoplasmic Reticulum | Compare the Difference Between Similar Terms Difference Between Sarcolemma and Sarcoplasmic Reticulum
Difference Between Sarcolemma and Sarcoplasmic Reticulum
Key Difference – Sarcolemma vs Sarcoplasmic Reticulum
CONTENTS
What is Sarcolemma?
What is Sarcoplasmic Reticulum?
Figure 02: Sarcoplasmic Reticulum
What are the Similarities Between Sarcolemma and Sarcoplasmic Reticulum?
What is the Difference Between Sarcolemma and Sarcoplasmic Reticulum?
Sarcolemma vs Sarcoplasmic Recticulum
Summary – Sarcolemma vs Sarcoplasmic Reticulum
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 Sarcolemma also contains various signal receiving receptors that are required in controlling the muscle cell activities. What is Sarcoplasmic Reticulum? Sarcoplasmic reticulum is similar to the endoplasmic reticulum of normal cells. Due to the specialized location, the muscle cell endoplasmic reticulum is referred to as the sarcoplasmic reticulum. This belongs to the smooth endoplasmic reticulum. It plays an important role in storage of calcium ions. The structure of sarcoplasmic reticulum is composed of a network of tubules. They are extended throughout the muscle cell and are seen to be wrapped around the myofibrils. The sarcoplasmic reticulum is situated in close proximity to the T tubules, and they are associated via the terminal cisternae. Three subfunctions can explain the overall function of calcium storage in the SR
Calcium Absorption
Calcium storage
Calcium release
In the phase of calcium absorption, the sarcoplasmic reticulum, absorb Calcium ions via the calcium pumps of the sarcoplasmic reticulum.

Difference Between Sarcolemma and Sarcoplasmic Reticulum | Compare the Difference Between Similar Terms

Difference Between Sarcolemma and Sarcoplasmic Reticulum
Difference Between Sarcolemma and Sarcoplasmic Reticulum
Key Difference – Sarcolemma vs Sarcoplasmic Reticulum
CONTENTS
What is Sarcolemma?
What is Sarcoplasmic Reticulum?
Figure 02: Sarcoplasmic Reticulum
What are the Similarities Between Sarcolemma and Sarcoplasmic Reticulum?
What is the Difference Between Sarcolemma and Sarcoplasmic Reticulum?
Sarcolemma vs Sarcoplasmic Recticulum
Summary – Sarcolemma vs Sarcoplasmic Reticulum
Download the PDF Sarcolemma vs Sarcoplasmic Reticulum
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About the Author: Samanthi
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Sarcolemma also contains various signal receiving receptors that are required in controlling the muscle cell activities. What is Sarcoplasmic Reticulum? Sarcoplasmic reticulum is similar to the endoplasmic reticulum of normal cells. Due to the specialized location, the muscle cell endoplasmic reticulum is referred to as the sarcoplasmic reticulum. This belongs to the smooth endoplasmic reticulum. It plays an important role in storage of calcium ions. The structure of sarcoplasmic reticulum is composed of a network of tubules. They are extended throughout the muscle cell and are seen to be wrapped around the myofibrils. The sarcoplasmic reticulum is situated in close proximity to the T tubules, and they are associated via the terminal cisternae. Three subfunctions can explain the overall function of calcium storage in the SR
Calcium Absorption
Calcium storage
Calcium release
In the phase of calcium absorption, the sarcoplasmic reticulum, absorb Calcium ions via the calcium pumps of the sarcoplasmic reticulum.

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Answered 2008-10-10 21:49:34
In skeletal muscle, a triad is formed when a T-Tubule is flanked
on either side by the calcium containing Terminal Cisternae of the
Sarcoplasmic Reticulum, at the level of the Z-line. The intimate
association of these three membranous sturctures (Terminal
Cisternae---T-Tubule---Terminal Cisternae) for a Triad. This
differs from a diad (or Dyad), in cardiac muscle where the T-Tubule
is only intimately associated with ONE Terminal Cisternae. 012
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What are the similarities between skeletal and cardiac muscle cells? cardiac is cardiac and skeletal is skeletal. Structural difference between cardiac muscle and skeletal muscle? comparing to skeletal muscles, cardiac muscle: longer t tubules
intercalated disks
smaller and shorter
What is the difference between striated smooth and cardiac muscle? The main difference is that striated (skeletal) muscle is
voluntary and cardiac and smooth (visceral) are involuntary.

Asked by Wiki User
See Answer
Top Answer
Wiki User
Answered 2008-10-10 21:49:34
In skeletal muscle, a triad is formed when a T-Tubule is flanked
on either side by the calcium containing Terminal Cisternae of the
Sarcoplasmic Reticulum, at the level of the Z-line. The intimate
association of these three membranous sturctures (Terminal
Cisternae---T-Tubule---Terminal Cisternae) for a Triad. This
differs from a diad (or Dyad), in cardiac muscle where the T-Tubule
is only intimately associated with ONE Terminal Cisternae. 012
0
0
0
0
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Your Answer
Loading...
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Related Questions
What are the similarities between skeletal and cardiac muscle cells? cardiac is cardiac and skeletal is skeletal. Structural difference between cardiac muscle and skeletal muscle? comparing to skeletal muscles, cardiac muscle: longer t tubules
intercalated disks
smaller and shorter
What is the difference between striated smooth and cardiac muscle? The main difference is that striated (skeletal) muscle is
voluntary and cardiac and smooth (visceral) are involuntary.

 It contains Ca 2+ (calcium ions) that are necessary for muscle contractions
What are terminal cristae? They are slender sacs that are at either ends of individual sarcoplasmic reticulum. They serve as reservoirs for the calcium ions
How many of them are on each sarcoplasmic reticulum? Two for each segment
What is the t tubule? It is another slender sac that lies between the two terminal cristae. They invaginate the sarcelomma, creating openings. What is the triad? The two terminal cristae and center T tubule create the triad of each sarcoplasmic reticulum
What is the sarcolemma? It is the plasma membrane of muscle fibers that has little openings on it created by T tubules
What are myofibrils? They are bundles of long cylindrical fibers within the sarcoplasmic reticulum.

It contains Ca 2+ (calcium ions) that are necessary for muscle contractions
What are terminal cristae? They are slender sacs that are at either ends of individual sarcoplasmic reticulum. They serve as reservoirs for the calcium ions
How many of them are on each sarcoplasmic reticulum? Two for each segment
What is the t tubule? It is another slender sac that lies between the two terminal cristae. They invaginate the sarcelomma, creating openings. What is the triad? The two terminal cristae and center T tubule create the triad of each sarcoplasmic reticulum
What is the sarcolemma? It is the plasma membrane of muscle fibers that has little openings on it created by T tubules
What are myofibrils? They are bundles of long cylindrical fibers within the sarcoplasmic reticulum.

What Are Dentin Tubules?
What Are Dentin Tubules?
What Are Dentin Tubules?
The Flow of Dentin Tubules
Dental Hypersensitivity
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 What Are Dentin Tubules? What Are Dentin Tubules? Overview
What Are Dentin Tubules? The Flow of Dentin Tubules
Dental Hypersensitivity
Have you heard of the term dentin tubules? Well, now you have. Dentin tubules are a vital part of your teeth. As you may know, the teeth are made up of tissue layers, and each one serves a unique function. The dentin tubules are located in the dentin, one of the layers below the enamel surface. The role of dentin tubules is to help you feel sensations in your teeth. That's also why they're often blamed for hypersensitivity in people's teeth.

What Are Dentin Tubules?

What Are Dentin Tubules?
What Are Dentin Tubules?
The Flow of Dentin Tubules
Dental Hypersensitivity
Was this article helpful?
RELATED PRODUCTS

What Are Dentin Tubules? What Are Dentin Tubules? Overview
What Are Dentin Tubules? The Flow of Dentin Tubules
Dental Hypersensitivity
Have you heard of the term dentin tubules? Well, now you have. Dentin tubules are a vital part of your teeth. As you may know, the teeth are made up of tissue layers, and each one serves a unique function. The dentin tubules are located in the dentin, one of the layers below the enamel surface. The role of dentin tubules is to help you feel sensations in your teeth. That's also why they're often blamed for hypersensitivity in people's teeth.

T Tubule Medical Definition | Merriam-Webster Medical Dictionary T tubule
T tubule
Medical Definition of T tubule
Learn More about T tubule
Dictionary Entries near T tubule
T tubule
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 T Tubule Medical Definition | Merriam-Webster Medical Dictionary
T tubule
noun
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Medical Definition of T tubule
: any of the small tubules which run transversely through a striated muscle fiber and through which electrical impulses are transmitted from the sarcoplasm to the fiber's interior
Learn More about T tubule
Dictionary Entries near T tubule
T system
TTP
T-tube
T tubule
tubal
tubal abortion
tubal ligation
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Cite this Entry
“T tubule.” Merriam-Webster.com Medical Dictionary, Merriam-Webster, https://www.merriam-webster.com/medical/T%20tubule. Accessed 1 Jun. 2021. Style: MLA
MLA Chicago APA Merriam-Webster
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T Tubule Medical Definition | Merriam-Webster Medical Dictionary

T tubule
T tubule
Medical Definition of T tubule
Learn More about T tubule
Dictionary Entries near T tubule
T tubule
Cite this Entry
Style: MLA
Love words? Need even more definitions?

T Tubule Medical Definition | Merriam-Webster Medical Dictionary
T tubule
noun
Save Word
To save this word, you'll need to log in. Log In
Medical Definition of T tubule
: any of the small tubules which run transversely through a striated muscle fiber and through which electrical impulses are transmitted from the sarcoplasm to the fiber's interior
Learn More about T tubule
Dictionary Entries near T tubule
T system
TTP
T-tube
T tubule
tubal
tubal abortion
tubal ligation
See More Nearby Entries
Cite this Entry
“T tubule.” Merriam-Webster.com Medical Dictionary, Merriam-Webster, https://www.merriam-webster.com/medical/T%20tubule. Accessed 1 Jun. 2021. Style: MLA
MLA Chicago APA Merriam-Webster
Love words? Need even more definitions? Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free! Merriam-Webster unabridged

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References
 T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research
Home Circulation Research Vol. 92, No. 11 T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Fabien Brette
and
Clive Orchard
Fabien Brette
Fabien Brette From the School of Biomedical Sciences, University of Leeds, Leeds, UK. Search for more papers by this author
and
Clive Orchard
Clive Orchard From the School of Biomedical Sciences, University of Leeds, Leeds, UK. Search for more papers by this author
Originally published 13 Jun 2003 https://doi.org/10.1161/01.RES.0000074908.17214.FD Circulation Research. 2003;92:1182–1192
Abstract
The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane. Recent studies have suggested that the structure and function of the t-tubules are more complex than previously believed; in particular, many of the proteins involved in cellular Ca 2+ cycling appear to be concentrated at the t-tubule. Thus, the t-tubules are an important determinant of cardiac cell function, especially as the main site of excitation-contraction coupling, ensuring spatially and temporally synchronous Ca 2+ release throughout the cell. Changes in t-tubule structure and protein expression occur during development and in heart failure, so that changes in the t-tubules may contribute to the functional changes observed in these conditions.

T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Abstract
Occurrence and Morphology of the T-Tubules
T-Tubule Development Is Labile
Proteins Present in the T-Tubule Membrane
Ca2+-Handling Proteins
Na+-Handling Proteins
K+-Handling Proteins
Anion-Handling Proteins
Second-Messenger Pathways
Interpretation of Immunohistochemical Data
Protein Colocalization Within, and With Proteins Adjacent to, the T-Tubules
Localization of Function
Cells Lacking T-Tubules
Diffusion Studies
Scanning Pipette
Detubulation
Functional Role
Electrical Properties of T-Tubules
Coupling of Ca 2+ Entry and Ca 2+ Release
Ca 2+ Efflux
Signal Transduction
Changes During Development and Disease
T-Tubule Development and Morphology in Hypertrophy and Failure
Changes in Protein Expression in Development, Hypertrophy, and Failure
Relevance of Changes in T-Tubule Structure and Protein Expression to Function
Conclusions and Unanswered Questions
Footnotes
References

T-Tubule Function in Mammalian Cardiac Myocytes | Circulation Research
Home Circulation Research Vol. 92, No. 11 T-Tubule Function in Mammalian Cardiac Myocytes
T-Tubule Function in Mammalian Cardiac Myocytes
Fabien Brette
and
Clive Orchard
Fabien Brette
Fabien Brette From the School of Biomedical Sciences, University of Leeds, Leeds, UK. Search for more papers by this author
and
Clive Orchard
Clive Orchard From the School of Biomedical Sciences, University of Leeds, Leeds, UK. Search for more papers by this author
Originally published 13 Jun 2003 https://doi.org/10.1161/01.RES.0000074908.17214.FD Circulation Research. 2003;92:1182–1192
Abstract
The transverse tubules (t-tubules) of mammalian cardiac ventricular myocytes are invaginations of the surface membrane. Recent studies have suggested that the structure and function of the t-tubules are more complex than previously believed; in particular, many of the proteins involved in cellular Ca 2+ cycling appear to be concentrated at the t-tubule. Thus, the t-tubules are an important determinant of cardiac cell function, especially as the main site of excitation-contraction coupling, ensuring spatially and temporally synchronous Ca 2+ release throughout the cell. Changes in t-tubule structure and protein expression occur during development and in heart failure, so that changes in the t-tubules may contribute to the functional changes observed in these conditions.

Release of Calcium Ions by the Sarcoplasmic Reticulum - Medical Physiology Release of Calcium Ions by the Sarcoplasmic Reticulum
Release of Calcium Ions by the Sarcoplasmic Reticulum
Figure 7-5
 Release of Calcium Ions by the Sarcoplasmic Reticulum - Medical Physiology
Release of Calcium Ions by the Sarcoplasmic Reticulum
Last Updated on Thu, 10 Dec 2020 | Medical Physiology
One of the special features of the sarcoplasmic reticulum is that within its vesicular tubules is an excess of calcium ions in high concentration, and many of these ions are released from each vesicle when an action potential occurs in the adjacent T tubule. Figure 7-6 shows that the action potential of the T tubule causes current flow into the sarcoplasmic reticular cisternae where they abut the T tubule. This in turn causes rapid opening of large numbers of calcium channels through the membranes of the cisternae as well as their attached longitudinal tubules. These channels remain open for a few milliseconds; during this time, enough calcium ions are released into the
Figure 7-5
Transverse (T) tubule-sarcoplas-mic reticulum system. Note that the T tubules communicate with the outside of the cell membrane, and deep in the muscle fiber, each T tubule lies adjacent to the ends of longitudinal sarcoplasmic reticulum tubules that surround all sides of the actual myofibrils that contract. This illustration was drawn from frog muscle, which has one T tubule per sarcomere, located at the Z line. A similar arrangement is found in mammalian heart muscle, but mammalian skeletal muscle has two T tubules per sarcomere, located at the A-I band junctions. ( Redrawn from Bloom W, Fawcett DW: A Textbook of Histology.

Release of Calcium Ions by the Sarcoplasmic Reticulum - Medical Physiology

Release of Calcium Ions by the Sarcoplasmic Reticulum
Release of Calcium Ions by the Sarcoplasmic Reticulum
Figure 7-5

Release of Calcium Ions by the Sarcoplasmic Reticulum - Medical Physiology
Release of Calcium Ions by the Sarcoplasmic Reticulum
Last Updated on Thu, 10 Dec 2020 | Medical Physiology
One of the special features of the sarcoplasmic reticulum is that within its vesicular tubules is an excess of calcium ions in high concentration, and many of these ions are released from each vesicle when an action potential occurs in the adjacent T tubule. Figure 7-6 shows that the action potential of the T tubule causes current flow into the sarcoplasmic reticular cisternae where they abut the T tubule. This in turn causes rapid opening of large numbers of calcium channels through the membranes of the cisternae as well as their attached longitudinal tubules. These channels remain open for a few milliseconds; during this time, enough calcium ions are released into the
Figure 7-5
Transverse (T) tubule-sarcoplas-mic reticulum system. Note that the T tubules communicate with the outside of the cell membrane, and deep in the muscle fiber, each T tubule lies adjacent to the ends of longitudinal sarcoplasmic reticulum tubules that surround all sides of the actual myofibrils that contract. This illustration was drawn from frog muscle, which has one T tubule per sarcomere, located at the Z line. A similar arrangement is found in mammalian heart muscle, but mammalian skeletal muscle has two T tubules per sarcomere, located at the A-I band junctions. ( Redrawn from Bloom W, Fawcett DW: A Textbook of Histology.

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 As T-tubules bring the sarcolemma very close to the sarcoplasmic reticulum at all regions throughout the cell, calcium can then be released from the sarcoplasmic reticulum across the whole cell at the same time. This synchronisation of calcium release allows muscle cells to contract more forcefully. In cells lacking T-tubules such as smooth muscle cells, diseased cardiomyocytes, or muscle cells in which T-tubules have been artificially removed, the calcium that enters at the sarcolemma has to diffuse gradually throughout the cell, activating the ryanodine receptors much more slowly as a wave of calcium leading to less forceful contraction. As the T-tubules are the primary location for excitation-contraction coupling, the ion channels and proteins involved in this process are concentrated here - there are 3 times as many L-type calcium channels located within the T-tubule membrane compared to the rest of the sarcolemma. Furthermore, beta adrenoceptors are also highly concentrated in the T-tubular membrane, and their stimulation increases calcium release from the sarcoplasmic reticulum. Calcium control
As the space within the lumen of the T-tubule is continuous with the space that surrounds the cell (the extracellular space), ion concentrations between the two are very similar. However, due to the importance of the ions within the T-tubules (particularly calcium in cardiac muscle), it is very important that these concentrations remain relatively constant. As the T-tubules are very thin, they essentially trap the ions. This is important as, regardless of the ion concentrations elsewhere in the cell, T-tubules still have enough calcium ions to permit muscle contraction. Therefore, even if the concentration of calcium outside the cell falls ( hypocalcaemia ), the concentration of calcium within the T-tubule remains relatively constant, allowing cardiac contraction to continue.

T-tubule - Wikipedia

T-tubule - Wikipedia

Hormones That Regulate Tubular Reabsorption - Medical Physiology Hormones That Regulate Tubular Reabsorption
Hormones That Regulate Tubular Reabsorption
Collecting tubule and duct
Recommended
 Hormones That Regulate Tubular Reabsorption - Medical Physiology
Hormones That Regulate Tubular Reabsorption
Last Updated on Wed, 06 Jan 2021 | Medical Physiology
Hormone
Aldosterone Angiotensin II
Antidiuretic hormone Atrial natriuretic peptide Parathyroid hormone
Site of Action
Collecting tubule and duct
Proximal tubule, thick ascending loop of Henle/distal tubule, collecting tubule Distal tubule/collecting tubule and duct Distal tubule/collecting tubule and duct Proximal tubule, thick ascending loop of Henle/distal tubule
Effects
T NaCl, H2O reabsorption, T K+ secretion T NaCl, H2O reabsorption, T H+ secretion
T H2O reabsorption 0 NaCl reabsorption 0 PO4 reabsorption, T Ca++
reabsorption reabsorption. First, efferent arteriolar constriction reduces peritubular capillary hydrostatic pressure, which increases net tubular reabsorption, especially from the proximal tubules. Second, efferent arteriolar constriction, by reducing renal blood flow, raises filtration fraction in the glomerulus and increases the concentration of proteins and the colloid osmotic pressure in the peritubular capillaries; this increases the reabsorptive force at the peritubular capillaries and raises tubular reabsorption of sodium and water. 3. Angiotensin II directly stimulates sodium reabsorption in the proximal tubules, the loops of Henle, the distal tubules, and the collecting tubules. One of the direct effects of angiotensin II is to stimulate the sodium-potassium ATPase pump on the tubular epithelial cell basolateral membrane. A second effect is to stimulate sodium-hydrogen exchange in the luminal membrane, especially in the proximal tubule. Thus, angiotensin II stimulates sodium transport across both the luminal and the basolateral surfaces of the epithelial cell membrane in the tubules. These multiple actions of angiotensin II cause marked sodium retention by the kidneys when angiotensin II levels are increased.

Hormones That Regulate Tubular Reabsorption - Medical Physiology

Hormones That Regulate Tubular Reabsorption
Hormones That Regulate Tubular Reabsorption
Collecting tubule and duct
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Renal tubule | definition of renal tubule by Medical dictionary renal tubule
renal tubule
tubule
renal tubule
Mentioned in ?
References in periodicals archive ?
Medical browser ?
Full browser ?
 dentinal t's the tubular structures of the teeth. galactophorous t's small channels for the passage of milk from the secreting cells in the mammary gland. Henle's t's the straight ascending and descending portions of a renal tubule forming Henle's loop. lactiferous t's galactophorous tubules. mesonephric t's the tubules comprising the mesonephros, or temporary kidney, of amniotes. metanephric t's the tubules comprising the permanent kidney of amniotes. renal tubule the minute canals composing the substance of the kidney and secreting, collecting and conducting the urine; in the glomerulus they have a basement membrane and epithelial lining. seminiferous t's the tubules of the testis, in which spermatozoa develop and through which they leave the gland. uriniferous t's renal tubules;

Renal tubule | definition of renal tubule by Medical dictionary

renal tubule
renal tubule
tubule
renal tubule
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dentinal t's the tubular structures of the teeth. galactophorous t's small channels for the passage of milk from the secreting cells in the mammary gland. Henle's t's the straight ascending and descending portions of a renal tubule forming Henle's loop. lactiferous t's galactophorous tubules. mesonephric t's the tubules comprising the mesonephros, or temporary kidney, of amniotes. metanephric t's the tubules comprising the permanent kidney of amniotes. renal tubule the minute canals composing the substance of the kidney and secreting, collecting and conducting the urine; in the glomerulus they have a basement membrane and epithelial lining. seminiferous t's the tubules of the testis, in which spermatozoa develop and through which they leave the gland. uriniferous t's renal tubules;

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. T-tubule structure and function are affected beat-by-beat by cardiomyocyte contraction, as well as by diseases, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1 Structure
1.1 Regulators
2 Function
2.1 Excitation-contraction coupling
2.2 Calcium control
2.3 Detubulation
3 History
4 Clinical significance
5 See also
6 References
Structure
T-tubules are tubules formed from the same phospholipid bilayer as the surface membrane or sarcolemma of skeletal or cardiac muscle cells. They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma. Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system. The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. T-tubules are found in both atrial and ventricular cardiac muscle cells ( cardiomyocytes ), in which they develop in the first few weeks of life. They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.

T-tubule - Wikipedia

Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. T-tubule structure and function are affected beat-by-beat by cardiomyocyte contraction, as well as by diseases, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1 Structure
1.1 Regulators
2 Function
2.1 Excitation-contraction coupling
2.2 Calcium control
2.3 Detubulation
3 History
4 Clinical significance
5 See also
6 References
Structure
T-tubules are tubules formed from the same phospholipid bilayer as the surface membrane or sarcolemma of skeletal or cardiac muscle cells. They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma. Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system. The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. T-tubules are found in both atrial and ventricular cardiac muscle cells ( cardiomyocytes ), in which they develop in the first few weeks of life. They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.

T-tubule - Wikipedia T-tubule
T-tubule
Contents
Structure
Regulators
Function
Excitation-contraction coupling
Calcium control
Detubulation
History
Clinical significance
See also
References
 Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. T-tubule structure may be affected by disease, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1 Structure
1.1 Regulators
2 Function
2.1 Excitation-contraction coupling
2.2 Calcium control
2.3 Detubulation
3 History
4 Clinical significance
5 See also
6 References
Structure
T-tubules are tubules formed from the same phospholipid bilayer as the surface membrane or sarcolemma of skeletal or cardiac muscle cells. They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma. Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system. The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. T-tubules are found in both atrial and ventricular cardiac muscle cells ( cardiomyocytes ), in which they develop in the first few weeks of life. They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.

T-tubule - Wikipedia

Through these mechanisms, T-tubules allow heart muscle cells to contract more forcefully by synchronising calcium release throughout the cell. T-tubule structure may be affected by disease, potentially contributing to heart failure and arrhythmias. Although these structures were first seen in 1897, research into T-tubule biology is ongoing. Contents
1 Structure
1.1 Regulators
2 Function
2.1 Excitation-contraction coupling
2.2 Calcium control
2.3 Detubulation
3 History
4 Clinical significance
5 See also
6 References
Structure
T-tubules are tubules formed from the same phospholipid bilayer as the surface membrane or sarcolemma of skeletal or cardiac muscle cells. They connect directly with the sarcolemma at one end before travelling deep within the cell, forming a network of tubules with sections running both perpendicular (transverse) to and parallel (axially) to the sarcolemma. Due to this complex orientation, some refer to T-tubules as the transverse-axial tubular system. The inside or lumen of the T-tubule is open at the cell surface, meaning that the T-tubule is filled with fluid containing the same constituents as the solution that surrounds the cell (the extracellular fluid). Rather than being just a passive connecting tube, the membrane that forms T-tubules is highly active, being studded with proteins including L-type calcium channels, sodium-calcium exchangers, calcium ATPases and Beta adrenoceptors. T-tubules are found in both atrial and ventricular cardiac muscle cells ( cardiomyocytes ), in which they develop in the first few weeks of life. They are found in ventricular muscle cells in most species, and in atrial muscle cells from large mammals.

Sarcoplasmic reticulum - Wikipedia Sarcoplasmic reticulum
Sarcoplasmic reticulum
Contents
Structure
Calcium absorption
Calcium storage
Calcium release
Role in rigor mortis
References
 This means that small increases in calcium ions within the cell are easily detected and can bring about important cellular changes (the calcium is said to be a second messenger; see calcium in biology for more details). Calcium is used to make calcium carbonate (found in chalk) and calcium phosphate, two compounds that the body uses to make teeth and bones. This means that too much calcium within the cells can lead to hardening ( calcification) of certain intracellular structures, including the mitochondria, leading to cell death. Therefore, it is vital that calcium ion levels are controlled tightly, and can be released into the cell when necessary and then removed from the cell. Contents
1 Structure
2 Calcium absorption
3 Calcium storage
4 Calcium release
5 Role in rigor mortis
6 References
Structure
The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct contact with) the myofibrils (contractile units of the cell). Cardiac and skeletal muscle cells contain structures called transverse tubules (T-tubules), which are extensions of the cell membrane that travel into the centre of the cell. T-tubules are closely associated with a specific region of the SR, known as the terminal cisternae in skeletal muscle, with a distance of roughly 12 nanometers, separating them. This is the primary site of calcium release. The longitudinal SR are thinner projects, that run between the terminal cisternae/junctional SR, and are the location where ion channels necessary for calcium ion absorption are most abundant.

Sarcoplasmic reticulum - Wikipedia

Sarcoplasmic reticulum
Sarcoplasmic reticulum
Contents
Structure
Calcium absorption
Calcium storage
Calcium release
Role in rigor mortis
References

This means that small increases in calcium ions within the cell are easily detected and can bring about important cellular changes (the calcium is said to be a second messenger; see calcium in biology for more details). Calcium is used to make calcium carbonate (found in chalk) and calcium phosphate, two compounds that the body uses to make teeth and bones. This means that too much calcium within the cells can lead to hardening ( calcification) of certain intracellular structures, including the mitochondria, leading to cell death. Therefore, it is vital that calcium ion levels are controlled tightly, and can be released into the cell when necessary and then removed from the cell. Contents
1 Structure
2 Calcium absorption
3 Calcium storage
4 Calcium release
5 Role in rigor mortis
6 References
Structure
The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct contact with) the myofibrils (contractile units of the cell). Cardiac and skeletal muscle cells contain structures called transverse tubules (T-tubules), which are extensions of the cell membrane that travel into the centre of the cell. T-tubules are closely associated with a specific region of the SR, known as the terminal cisternae in skeletal muscle, with a distance of roughly 12 nanometers, separating them. This is the primary site of calcium release. The longitudinal SR are thinner projects, that run between the terminal cisternae/junctional SR, and are the location where ion channels necessary for calcium ion absorption are most abundant.

Sarcoplasmic reticulum - Wikipedia Sarcoplasmic reticulum
Sarcoplasmic reticulum
Contents
Structure
Calcium absorption
Calcium storage
Calcium release
Role in rigor mortis
References
 Contents
1 Structure
2 Calcium absorption
3 Calcium storage
4 Calcium release
5 Role in rigor mortis
6 References
Structure
The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct contact with) the myofibrils (contractile units of the cell). Cardiac and skeletal muscle cells contain structures called transverse tubules (T-tubules), which are extensions of the cell membrane that travel into the centre of the cell. T-tubules are closely associated with a specific region of the SR, known as the terminal cisternae in skeletal muscle, with a distance of roughly 12 nanometers, separating them. This is the primary site of calcium release. The longitudinal SR are thinner projects, that run between the terminal cisternae/junctional SR, and are the location where ion channels necessary for calcium ion absorption are most abundant. These processes are explained in more detail below and are fundamental for the process of excitation-contraction coupling in skeletal, cardiac and smooth muscle . Calcium absorption
The SR contains ion channel pumps, within its membrane that are responsible for pumping Ca 2+ into the SR. As the calcium ion concentration within the SR is higher than in the rest of the cell, the calcium ions won't freely flow into the SR, and therefore pumps are required, that use energy, which they gain from a molecule called adenosine triphosphate (ATP). These calcium pumps are called Sarco (endo)plasmic reticulum Ca 2+ ATPases (SERCA). There are a variety of different forms of SERCA, with SERCA 2a being found primarily in cardiac and skeletal muscle.

Sarcoplasmic reticulum - Wikipedia

Contents
1 Structure
2 Calcium absorption
3 Calcium storage
4 Calcium release
5 Role in rigor mortis
6 References
Structure
The sarcoplasmic reticulum is a network of tubules that extend throughout muscle cells, wrapping around (but not in direct contact with) the myofibrils (contractile units of the cell). Cardiac and skeletal muscle cells contain structures called transverse tubules (T-tubules), which are extensions of the cell membrane that travel into the centre of the cell. T-tubules are closely associated with a specific region of the SR, known as the terminal cisternae in skeletal muscle, with a distance of roughly 12 nanometers, separating them. This is the primary site of calcium release. The longitudinal SR are thinner projects, that run between the terminal cisternae/junctional SR, and are the location where ion channels necessary for calcium ion absorption are most abundant. These processes are explained in more detail below and are fundamental for the process of excitation-contraction coupling in skeletal, cardiac and smooth muscle . Calcium absorption
The SR contains ion channel pumps, within its membrane that are responsible for pumping Ca 2+ into the SR. As the calcium ion concentration within the SR is higher than in the rest of the cell, the calcium ions won't freely flow into the SR, and therefore pumps are required, that use energy, which they gain from a molecule called adenosine triphosphate (ATP). These calcium pumps are called Sarco (endo)plasmic reticulum Ca 2+ ATPases (SERCA). There are a variety of different forms of SERCA, with SERCA 2a being found primarily in cardiac and skeletal muscle.

 A muscle contraction in which shortening occurs. What is the functional role of the T tubules? enhance cellular communication during muscle contraction. What role does the nervous system play in muscle contraction? controls the muscles by the motor nurons. What compound is formed in oxidation that supplies the energy for contraction? Myoglobin glycogen creatine
What is the compound that stores oxygen in muscle cells? myoglobin
The pinkish pigment of the muscle that stores oxygen? MYOGLOBIN
BiologyMuscular SystemElements and CompoundsCardiovascular HealthMedication and DrugsGeneticsChemical BondingHuman Anatomy and PhysiologyOrganic ChemistryShorteningExercise
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A muscle contraction in which shortening occurs. What is the functional role of the T tubules? enhance cellular communication during muscle contraction. What role does the nervous system play in muscle contraction? controls the muscles by the motor nurons. What compound is formed in oxidation that supplies the energy for contraction? Myoglobin glycogen creatine
What is the compound that stores oxygen in muscle cells? myoglobin
The pinkish pigment of the muscle that stores oxygen? MYOGLOBIN
BiologyMuscular SystemElements and CompoundsCardiovascular HealthMedication and DrugsGeneticsChemical BondingHuman Anatomy and PhysiologyOrganic ChemistryShorteningExercise
Trending Questions
what is 9 inch + 5 inch? Asked By
                            Sophia Sneed
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Transverse Tubular System - an overview | ScienceDirect Topics Transverse Tubular System
Transverse Tubular System
Cardiovascular Physiology
Transverse Tubules
Ion Channel Trafficking
T-Tubules
Functional Organization of Vertebrate Plasma Membrane
2.4 T-tubules, physiology, and disease
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Cardiac Rhythm
4.2.1 Ca++ Regulation
Cardiovascular Physiology
Membrane Depolarization and Activator Calcium
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Ion Channel Trafficking in the Heart
Ca V 1.2 Channel Trafficking in the Heart
Ca V 1.2 Forward Trafficking in Normal Heart Physiology
Ca V 1.2 Forward Trafficking in Heart Pathophysiology
Accessory Proteins Involved in Ca V 1.2 Targeted Delivery
T-Tubules and Ca V 1.2 Regulation in Normal Heart Physiology
T-Tubules and Ca V 1.2 Regulation in Heart Pathophysiology
Ca V 1.2 Internalization
Muscles
Coupling Action Potentials to Contraction
Skeletal Muscle Excitability
AIII Further Evidence that the T-Tubules Fire Na + -Dependent AP s
 In a spontaneously hypertensive rat model, distinct changes in the T-tubule system were reported, specifically a dramatic reorganization of the T-tubule system ( Song et al., 2006 ). The T-tubule system in this model was characterized by a loss of transverse elements but a gain in longitudinal elements, producing a T-tubule network with a chaotic appearance ( Song et al., 2006 ). Notably, in this same study, the organization of the SR as noted by RyR 2 distribution was unaffected. Disruption or loss of the T-tubule network is also observed in human cardiac myocytes from patients with heart failure ( Lyon et al., 2009 ). Patients with hypertrophic cardiomyopathy, dilated cardiomyopathy, and ischemic heart disease all exhibit profound T-tubule abnormalities, including reduction in T-tubule density and cell surface regularity ( Lyon et al., 2009 ). Additionally, human failing myocytes have T-tubules that lie on the longitudinal axis and are more often dilated and bifurcated.

Transverse Tubular System - an overview | ScienceDirect Topics

Transverse Tubular System
Transverse Tubular System
Cardiovascular Physiology
Transverse Tubules
Ion Channel Trafficking
T-Tubules
Functional Organization of Vertebrate Plasma Membrane
2.4 T-tubules, physiology, and disease
Skeletal Muscle
T-tubules Are Surface Invaginations; the SR Is an Internal Membrane System
Cardiac Rhythm
4.2.1 Ca++ Regulation
Cardiovascular Physiology
Membrane Depolarization and Activator Calcium
Structure and Function of Calcium Release Channels
2 T Tubules and CRUs Revert to More Primitive Forms Under Pathological Conditions
Ion Channel Trafficking in the Heart
Ca V 1.2 Channel Trafficking in the Heart
Ca V 1.2 Forward Trafficking in Normal Heart Physiology
Ca V 1.2 Forward Trafficking in Heart Pathophysiology
Accessory Proteins Involved in Ca V 1.2 Targeted Delivery
T-Tubules and Ca V 1.2 Regulation in Normal Heart Physiology
T-Tubules and Ca V 1.2 Regulation in Heart Pathophysiology
Ca V 1.2 Internalization
Muscles
Coupling Action Potentials to Contraction
Skeletal Muscle Excitability
AIII Further Evidence that the T-Tubules Fire Na + -Dependent AP s

In a spontaneously hypertensive rat model, distinct changes in the T-tubule system were reported, specifically a dramatic reorganization of the T-tubule system ( Song et al., 2006 ). The T-tubule system in this model was characterized by a loss of transverse elements but a gain in longitudinal elements, producing a T-tubule network with a chaotic appearance ( Song et al., 2006 ). Notably, in this same study, the organization of the SR as noted by RyR 2 distribution was unaffected. Disruption or loss of the T-tubule network is also observed in human cardiac myocytes from patients with heart failure ( Lyon et al., 2009 ). Patients with hypertrophic cardiomyopathy, dilated cardiomyopathy, and ischemic heart disease all exhibit profound T-tubule abnormalities, including reduction in T-tubule density and cell surface regularity ( Lyon et al., 2009 ). Additionally, human failing myocytes have T-tubules that lie on the longitudinal axis and are more often dilated and bifurcated.

Convoluted - definition of convoluted by The Free Dictionary convoluted
convoluted
con·vo·lut·ed
convoluted
ˈconvoˌlutedly adv
ˈconvoˌlutedness n
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con′vo•lut`ed•ly, adv.
con′vo•lut`ed•ness, n.
convoluted
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Muscles and Muscle tissue Flashcards | Quizlet Muscles and Muscle tissue
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THIS SET IS OFTEN IN FOLDERS WITH...
A&P Lecture Ch. 8,9,11
Module 3: Section 9.04
Mastering A&P Chapter 3 - Cells: The Liv…
Anatomy and Physiology Chapter 9 Part 1
 What is name given to the regularly spaced infoldings of the sarcolemma? A) Sarcoplasmic reticulum
B) motor endplates
C) terminal cisternae
D) transverse or T tubules
transverse or t-tubules (T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior.) Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? A) sodium ions
B) calcium ions
C) Acetylcholine
D) Action potentials
Calcium ions (Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm. This flood of calcium ions is directly responsible for the coupling of excitation to contraction in skeletal muscle fibers.) What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated? A) A skeletal muscle fiber is innervated by multiple motor neurons. B) Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron. C) A motor neuron typically innervates only one skeletal muscle fiber.

What is name given to the regularly spaced infoldings of the sarcolemma? A) Sarcoplasmic reticulum
B) motor endplates
C) terminal cisternae
D) transverse or T tubules
transverse or t-tubules (T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior.) Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? A) sodium ions
B) calcium ions
C) Acetylcholine
D) Action potentials
Calcium ions (Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm. This flood of calcium ions is directly responsible for the coupling of excitation to contraction in skeletal muscle fibers.) What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated? A) A skeletal muscle fiber is innervated by multiple motor neurons. B) Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron. C) A motor neuron typically innervates only one skeletal muscle fiber.

Smooth Muscle Physiology Flashcards | Quizlet Smooth Muscle Physiology
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 Although smooth muscle cells contain thick myosin filaments and thin actin filaments, the contractile elements (and cytoskeletal elements) are not arranged transversely as they are in striated (skeletal and cardiac) muscle. This lack of striations results in an apparent lack of organization in light and electron micrographs of smooth muscle cells, which in the past has sometimes led to the conclusion that smooth muscle is more poorly developed than skeletal and cardiac muscle. However, smooth muscle is highly specialized for its role in the body. The organization of its contractile apparatus remains less well understood than that of striated muscle, but this may simply reflect the need for improved 3 D imaging techniques. The dense bodies of smooth muscle are analogous to x in skeletal and cardiac muscle
Z-lines
T/F - Unlike skeletal muscle, smooth muscle does not have troponin, t-tubules, or SR
False - smooth muscle DOES NOT have troponin or t-tubules, but it does have some SR, but less developed than in skeletal muscle
Smooth muscle cells contain three types of filaments: 1. Thick x filaments are longer than those in skeletal muscle. 2. Thin x filaments. Unlike skeletal and cardiac muscle these filaments DO NOT contain x and x (although they do contain proteins called calponin and caldesmon that may serve regulatory roles).

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Smooth Muscle Physiology
Smooth Muscle Physiology
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Although smooth muscle cells contain thick myosin filaments and thin actin filaments, the contractile elements (and cytoskeletal elements) are not arranged transversely as they are in striated (skeletal and cardiac) muscle. This lack of striations results in an apparent lack of organization in light and electron micrographs of smooth muscle cells, which in the past has sometimes led to the conclusion that smooth muscle is more poorly developed than skeletal and cardiac muscle. However, smooth muscle is highly specialized for its role in the body. The organization of its contractile apparatus remains less well understood than that of striated muscle, but this may simply reflect the need for improved 3 D imaging techniques. The dense bodies of smooth muscle are analogous to x in skeletal and cardiac muscle
Z-lines
T/F - Unlike skeletal muscle, smooth muscle does not have troponin, t-tubules, or SR
False - smooth muscle DOES NOT have troponin or t-tubules, but it does have some SR, but less developed than in skeletal muscle
Smooth muscle cells contain three types of filaments: 1. Thick x filaments are longer than those in skeletal muscle. 2. Thin x filaments. Unlike skeletal and cardiac muscle these filaments DO NOT contain x and x (although they do contain proteins called calponin and caldesmon that may serve regulatory roles).

 The association of the T-tubule with a terminal cistern is known as a diad. [ 5]
In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad. [ 1][6]
Regulators[edit]
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2is encoded by the gene BIN1and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane.[7] Junctophilin-2 is encoded by the gene JPH2and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling.[5] Titin capping protein or Telethonin is encoded by the gene TCAPand helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. [ 5]
Function[edit]
Excitation-contraction coupling[edit]
See also: Excitation-contraction coupling
T-tubules are an important link in the chain from electrical excitation of a cell to its subsequent contraction (excitation-contraction coupling). When contraction of a muscle is needed, stimulation from a nerve or an adjacent muscle cell causes a characteristic flow of charged particlesacross the cell membrane known as an action potential. At rest, there are fewer positively charged particles on the inner side of the membrane compared to the outer side, and the membrane is described as being polarised. During an action potential, positively charged particles (predominantly sodium and calcium ions) flow across the membrane from the outside to the inside.

The association of the T-tubule with a terminal cistern is known as a diad. [ 5]
In skeletal muscle cells, T-tubules are between 20 and 40 nm in diameter and are typically located either side of the myosin strip, at the junction of overlap between the A and I bands. T-tubules in skeletal muscle are associated with two terminal cisternae, known as a triad. [ 1][6]
Regulators[edit]
The shape of the T-tubule system is produced and maintained by a variety of proteins. The protein amphiphysin-2is encoded by the gene BIN1and is responsible for forming the structure of the T-tubule and ensuring that the appropriate proteins (in particular L-type calcium channels) are located within the T-tubule membrane.[7] Junctophilin-2 is encoded by the gene JPH2and helps to form a junction between the T-tubule membrane and the sarcoplasmic reticulum, vital for excitation-contraction coupling.[5] Titin capping protein or Telethonin is encoded by the gene TCAPand helps with T-tubule development and is potentially responsible for the increasing number of T-tubules seen as muscles grow. [ 5]
Function[edit]
Excitation-contraction coupling[edit]
See also: Excitation-contraction coupling
T-tubules are an important link in the chain from electrical excitation of a cell to its subsequent contraction (excitation-contraction coupling). When contraction of a muscle is needed, stimulation from a nerve or an adjacent muscle cell causes a characteristic flow of charged particlesacross the cell membrane known as an action potential. At rest, there are fewer positively charged particles on the inner side of the membrane compared to the outer side, and the membrane is described as being polarised. During an action potential, positively charged particles (predominantly sodium and calcium ions) flow across the membrane from the outside to the inside.

BSS2085 Mastering A&P Flashcards - Cram.com Bss2085 Mastering A&p
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 It is especially abundant and convoluted in skeletal muscle cells. It functions in the storage, release, and reuptake of calcium ions.) A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected? A series of proteins that control calcium release

What is name given to the regularly spaced infoldings of the sarcolemma? transverse or T tubules
(T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior)

Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. (Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm. This flood of calcium ions is directly responsible for the coupling of excitation to contraction in skeletal muscle fibers.)

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Bss2085 Mastering A&p
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It is especially abundant and convoluted in skeletal muscle cells. It functions in the storage, release, and reuptake of calcium ions.) A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected? A series of proteins that control calcium release

What is name given to the regularly spaced infoldings of the sarcolemma? transverse or T tubules
(T tubules penetrate a skeletal muscle fiber and provide a pathway for excitation into the interior)

Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers? Calcium ions. (Action potentials propagating down the T-tubule cause a voltage-sensitive protein to change shape. This shape change opens calcium release channels in the sarcoplasmic reticulum, allowing calcium ions to flood the sarcoplasm. This flood of calcium ions is directly responsible for the coupling of excitation to contraction in skeletal muscle fibers.)