where are cardiac muscles found in the body
Anatomical terms of muscle


Muscles are described using unique anatomical terminology according to their actions and structure. There are three types of muscle tissue in the human body: skeletal, smooth, and cardiac. Skeletal striated muscle, or "voluntary muscle", primarily joins to bone with tendons. Skeletal muscle enables movement of the bones of the human skeleton and maintains posture. Smooth muscle tissue is found in parts of the body where it conveys action without conscious intent. The majority of this type of muscle tissue is found in the digestive and urinary systems where
19358514
Tissue (biology)


connective tissue. Muscle cells form the active contractile tissue of the body known as muscle tissue or muscular tissue. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle tissue is separated into three distinct categories: visceral or smooth muscle, found in the inner linings of organs; skeletal muscle, typically attached to bones, which generate gross movement; and cardiac muscle, found in the heart, where it contracts to pump blood throughout an organism. Cells comprising the central nervous system and
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Muscular system


The muscular system is an organ system consisting of skeletal, smooth and cardiac muscles. It permits movement of the body, maintains posture and circulates blood throughout the body. The muscular systems in vertebrates are controlled through the nervous system although some muscles (such as the cardiac muscle) can be completely autonomous. Together with the skeletal system, it forms the musculoskeletal system, which is responsible for movement of the human body. There are three distinct types of muscles: skeletal muscles, cardiac or heart muscles, and smooth (non
999340
Muscle contraction


also known as jumper's knee or patellar tendonosis) have been shown to benefit from high-load eccentric contractions. In vertebrate animals, there are three types of muscle tissues: skeletal, smooth, and cardiac. Skeletal muscle constitutes the majority of muscle mass in the body and is responsible for locomotor activity. Smooth muscle forms blood vessels, gastrointestinal tract, and other areas in the body that produce sustained contractions. Cardiac muscle make up the heart, which pumps blood. Skeletal and cardiac muscles are called striated muscle because of
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Muscle tissue


Muscle tissue is a soft tissue that composes muscles in animal bodies, and gives rise to muscles' ability to contract. This is opposed to other components or tissues in muscle such as tendons or perimysium. It is formed during embryonic development through a process known as myogenesis. Muscle tissues varies with function and location in the body. In mammals the three types are: skeletal or striated muscle; smooth or non-striated muscle; and cardiac muscle, which is sometimes known as semi-striated. Smooth and cardiac muscle contracts
14873531
Anatomy


, many glands are formed of epithelial cells. Muscle cells (myocytes) form the active contractile tissue of the body. Muscle tissue functions to produce force and cause motion, either locomotion or movement within internal organs. Muscle is formed of contractile filaments and is separated into three main types; smooth muscle, skeletal muscle and cardiac muscle. Smooth muscle has no striations when examined microscopically. It contracts slowly but maintains contractibility over a wide range of stretch lengths. It is found in such organs as sea anemone tentacles and the body
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Human musculoskeletal system


musculoskeletal system and only the skeletal muscles can move the body. Cardiac muscles are found in the heart and are used only to circulate blood; like the smooth muscles, these muscles are not under conscious control. Skeletal muscles are attached to bones and arranged in opposing groups around joints. Muscles are innervated, to communicate nervous energy to, by nerves, which conduct electrical currents from the central nervous system and cause the muscles to contract. In mammals, when a muscle contracts, a series of reactions occur. Muscle contraction is
6590959
Muscle tissue


termed uterine smooth muscle), male and female reproductive tracts, gastrointestinal tract, respiratory tract, arrector pili of skin, the ciliary muscle, and iris of the eye. The structure and function is basically the same in smooth muscle cells in different organs, but the inducing stimuli differ substantially, in order to perform individual effects in the body at individual times. In addition, the glomeruli of the kidneys contain smooth muscle-like cells called mesangial cells. Cardiac muscle is involuntary, striated muscle that is found in the walls
14873537
Muscle tissue


of cardiac muscle cells in the heart propel blood out of the atria and ventricles to the blood vessels of the left/body/systemic and right/lungs/pulmonary circulatory systems. This complex mechanism illustrates systole of the heart. Cardiac muscle cells, unlike most other tissues in the body, rely on an available blood and electrical supply to deliver oxygen and nutrients and remove waste products such as carbon dioxide. The coronary arteries help fulfill this function. 1. They carry out movements of the body. 2. They support
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T-tubule


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
4056656
Muscle


, the fibers in cardiac muscle are typically branched to form a network. Cardiac muscle fibers are interconnected by intercalated discs, giving that tissue the appearance of a syncytium. The filaments in a sarcomere are composed of actin and myosin. The gross anatomy of a muscle is the most important indicator of its role in the body. There is an important distinction seen between pennate muscles and other muscles. In most muscles, all the fibers are oriented in the same direction, running in a line from the origin to the insertion.
16060829
Blood doping


methods (e.g. increase aerobic capacity by maximizing the uptake of O) in order to enhance the O transport of the body to the muscles. The body undergoes aerobic respiration in order to provide sufficient delivery of O to the exercising skeletal muscles and the main determining factors are shown in figure 1. The rate of maximum O uptake (Omax) depends on cardiac output, O extraction and hemoglobin mass. The cardiac output of an athlete is difficult to manipulate during competitions and the distribution of cardiac output is at the maximum rate (
5772535
Troponin


muscle begins. Troponin is found in both skeletal muscle and cardiac muscle, but the specific versions of troponin differ between types of muscle. The main difference is that the TnC subunit of troponin in skeletal muscle has four calcium ion-binding sites, whereas in cardiac muscle there are only three. Views on the actual amount of calcium that binds to troponin vary from expert to expert and source to source. In both cardiac and skeletal muscles, muscular force production is controlled primarily by changes in the intracellular calcium concentration. In general
18674209
Cardiac fibroma


causing the formation of tumors in various parts of the body. Research is currently being undertaken to identify relevant casual factors. The mechanism behind cardiac fibromas are still unclear. Fibromas have a homogeneous mass of fibroblasts mixed with an abundance of collagen and elastic fibers. These masses represent mesenchymal growth, but lacks other mesenchymal elements, such as blood vessels, cartilage bone, and muscle. They often entrap cardiomyocytes, which are muscle cells that make up the cardiac muscle. Cells are decreasing during this time, while collagen contents are increasing
4220229
T-type calcium channel


in this case calcium, through the membrane when the channel is activated. When membrane depolarization occurs in a cell membrane where these channels are embedded, they open and allow calcium to enter the cell, which leads to several different cellular events depending on where in the body the cell is found. As a member of the Ca3 subfamily of voltage-gated calcium channels, the function of the T-type channel is important for the repetitive firing of action potentials in cells with rhythmic firing patterns such as cardiac muscle cells and neurons
5705232
Nutritional muscular dystrophy


are antioxidants therefore, deficiencies of these nutrients leads to oxidative damage to cells within the body. The muscle cells are the most vulnerable to damage in livestock species. The oxidative damage causes degeneration of muscles, in particular those within the skeletal and cardiac systems. If the cardiac muscles are impaired the animal may exhibit signs of respiratory distress. While deterioration of skeletal muscles results in stiffness, weakness, and recumbency. If the diet is deficient supplement with selenium and/or vitamin E. Injections can be given to treat the condition or as a
10665662
Actinin


Actinin is a microfilament protein. α-Actinin is necessary for the attachment of actin filaments to the Z-lines in skeletal muscle cells, and to the dense bodies in smooth muscle cells. The functional protein is an anti-parallel dimer, which cross-links the thin filaments in adjacent sarcomeres, and therefore coordinates contractions between sarcomeres in the horizontal axis. The non-sarcomeric α-actinins, encoded by ACTN1 and ACTN4, are widely expressed. ACTN2 expression is found in both cardiac and skeletal muscle, whereas ACTN3
4913159
Lactate shuttle hypothesis


majority of lactate turnover in the human body (as evidenced by the slight increases in arterial lactate concentration). Brooks et al. confirmed this in 1999, when they found that lactate oxidation exceeded that of pyruvate by 10-40% in rat liver, skeletal, and cardiac muscle. In 1990, Roth and Brooks found evidence for the facilitated transporter of lactate, monocarboxylate transport protein (MCT), in the sarcolemma vesicles of rat skeletal muscle. Later, MCT1 was the first of the MCT super family to be identified
16914765
CSRP3


Cysteine and glycine-rich protein 3 also known as cardiac LIM protein (CLP) or muscle LIM protein (MLP) is a protein that in humans is encoded by the CSRP3 gene. CSRP3 IS a small 194 amino acid protein, which is specifically expressed in skeletal and cardiac muscle. In rodents, CSRP3 has also been found to be expressed in neurons. The CSRP3 gene was discovered in rat in 1994. In humans it was mapped to chromosome 11p15.1, where it spans a 20kb genomic region, organized in 6
1947706
Anatomical terms of muscle


it acts by propelling forward food, chyme, and feces in the former and urine in the latter. Other places smooth muscle can be found are within the uterus, where it helps facilitate birth, and the eye, where the pupillary sphincter controls pupil size. Cardiac muscle is specific to the heart. It is also involuntary in its movement, and is additionally self-excitatory, contracting without outside stimuli. As well as anatomical terms of motion, which describe the motion made by a muscle, unique terminology is used to
19358515
Myocyte


A myocyte (also known as a muscle cell) is the type of cell found in muscle tissue. Myocytes are long, tubular cells that develop from myoblasts to form muscles in a process known as myogenesis. There are various specialized forms of myocytes with distinct properties: cardiac, skeletal, and smooth muscle cells. The striated cells of cardiac and skeletal muscles are referred to as muscle fibers. Cardiomyocytes are the muscle fibres that form the chambers of the heart, and have a single central nucleus. Skeletal muscle fibers help support
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Cardiac excitation-contraction coupling


Cardiac excitation-contraction coupling (Cardiac EC coupling) describes the series of events, from the production of an electrical impulse (action potential) to the contraction of muscles in the heart. This process is of vital importance as it allows for the heart to beat in a controlled manner, without the need for conscious input. EC coupling results in the sequential contraction of the heart muscles that allows blood to be pumped, first to the lungs (pulmonary circulation) and then around the rest of the body (systemic circulation)
14747272
Nav1.5


Na1.5 is an integral membrane protein and tetrodotoxin-resistant voltage-gated sodium channel subunit. Na1.5 is found primarily in cardiac muscle, where it mediates the fast influx of Na-ions (I) across the cell membrane, resulting in the fast depolarization phase of the cardiac action potential. As such, it plays a major role in impulse propagation through the heart. A vast number of cardiac diseases is associated with mutations in Na1.5 (see paragraph genetics). "SCN5A" is the gene that encodes the cardiac sodium channel
10907806
Plakophilin-2


Plakophilin-2 is a protein that in humans is encoded by the "PKP2" gene. Plakophilin 2 is expressed in skin and cardiac muscle, where it functions to link cadherins to intermediate filaments in the cytoskeleton. In cardiac muscle, plakophilin-2 is found in desmosome structures located within intercalated discs. Mutations in "PKP2" have been shown to be causal in arrhythmogenic right ventricular cardiomyopathy. Two splice variants of the "PKP2" gene have been identified. The first has a molecular weight of 97.4 kDa (881 amino acids) and the
21215271
Cardiac neural crest cells


form the ears) to the third somites (clusters of mesoderm that will become skeletal muscle, vertebrae and dermis). The cardiac neural crest cells have a number of functions including creation of the muscle and connective tissue walls of large arteries; parts of the cardiac septum; parts of the thyroid, parathyroid and thymus glands. They differentiate into melanocytes and neurons and the cartilage and connective tissue of the pharyngeal arches. They may also contribute to the creation of the carotid body, the organ which monitors oxygen in the blood and
11160455
Cardiovascular centre


in carotid bodies, or a change of blood pressure is detected by baroreceptors in the aortic sinuses or carotid sinuses, the cardiovascular centre affects changes to the heart rate by sending a nerve impulse to the cardiac pacemaker (or SA node) via sympathetic fibres (to cause faster and stronger cardiac muscle contraction) and the vagus nerve (to cause slower and less strong cardiac muscle contraction). The cardiovascular centre also increases the stroke volume of the heart (that is, the amount of blood it pumps). These two changes
414966
Phospholamban


Phospholamban, also known as PLN or PLB, is a micropeptide protein that in humans is encoded by the "PLN" gene. Phospholamban is a 52-amino acid integral membrane protein that regulates the Calcium (Ca) pump in cardiac muscle cells. This protein is found as a pentamer and is a major substrate for the cAMP-dependent protein kinase (PKA) in cardiac muscle. In the unphosphorylated state, phospholamban is an inhibitor of cardiac muscle sarcoplasmic reticulum Ca-ATPase (SERCA2) which transports calcium from cytosol into the sarcoplasmic
3438274
Curare


syndrome in that there is paralysis of every voluntarily controlled muscle in the body (including the eyes), making it practically impossible for the victim to confirm consciousness while paralyzed. Spontaneous breathing is resumed after the end of the duration of action of curare, which is generally between 30 minutes to 8 hours, depending on the variant of the toxin and dosage. Cardiac muscle is not directly affected by curare, but if more than four to six minutes has passed since respiratory cessation the cardiac muscle may stop functioning by oxygen-deprivation
3526187
Muscle


to the appropriate locations, where they fuse into elongate skeletal muscle cells. The three types of muscle (skeletal, cardiac and smooth) have significant differences. However, all three use the movement of actin against myosin to create contraction. In skeletal muscle, contraction is stimulated by electrical impulses transmitted by the nerves, the motoneurons (motor nerves) in particular. Cardiac and smooth muscle contractions are stimulated by internal pacemaker cells which regularly contract, and propagate contractions to other muscle cells they are in contact with. All skeletal muscle
16060835
Phosphoglycerate mutase


-type) or other tissue (b-type for brain where the b-isozyme was originally isolated). Existing as a dimer, the enzyme then has 3 isozymes depending on which subunit forms makeup the whole molecule (mm, bb or mb). The mm-type is found mainly in smooth muscle almost exclusively. The mb-isozyme is found in cardiac and skeletal muscle and the bb-type is found in the rest of tissues. While all three isozymes may be found in any tissue, the above
2664716
Gap junction


in cardiac muscle: the signal to contract is passed efficiently through gap junctions, allowing the heart muscle cells to contract in unison. Gap junctions are expressed in virtually all tissues of the body, with the exception of adult fully developed skeletal muscle and mobile cell types such as sperm or erythrocytes. Several human genetic disorders are associated with mutations in gap junction genes. Many of those affect the skin because this tissue is heavily dependent upon gap junction communication for the regulation of differentiation and proliferation. Cardiac gap junctions can pharmacologically be opened
19875672
Desmin


desmin's function early in development but not later on. In adult desmin-null mice, hearts from 10 wk-old animals showed drastic alterations in muscle architecture, including a misalignment of myofibrils and disorganization and swelling of mitochondria; findings that were more severe in cardiac relative to skeletal muscle. Cardiac tissue also exhibited progressive necrosis and calcification of the myocardium. A separate study examined this in more detail in cardiac tissue and found that murine hearts lacking desmin developed hypertrophic cardiomyopathy and chamber dilation combined with systolic dysfunction. In adult muscle
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Pharmacoepigenetics


incorporated into DNA and then recognized as a substrate for DNA methyltransferases, but since the enzyme is bound the methyltransferase cannot add methylation marks and thus silence crucial genes. Histone modifications, DNA methylation, and microRNAs have been found to play an important role in heart disease. Previously, histone tail acetylation has been linked to cardiac hypertrophy or abnormal heart muscle thickening that is usually due to an increase in cardiomyocyte size or other cardiac muscle changes. The hypertrophic changes that occur in cardiac muscles cells result from the required acetylation of histone
4550804
Calciseptine


in excitable cells like neurons and cardiac or smooth muscle cells. N-type Ca channels are found in neuronal cells, and play an important role in the coupling of nerve excitation and neurotransmitter secretion. L-type calcium channels are present in cardiac and smooth muscle cells, coupling excitation to muscle contraction. Other types of voltage-activated Ca-channels include T-type and P-type channels. Because the presence of calcium in the cytosol is required for muscle contraction, blockers of calcium channels prevent the muscles from building
15181254
Dextro-Transposition of the great arteries


heart muscle eventually leads to hypertrophy and may result in cardiac arrest if left untreated. In a normal heart, oxygen-depleted ("blue") blood is pumped from the right side of the heart, through the pulmonary artery, to the lungs where it is oxygenated. The oxygen-rich ("red") blood then returns to the left heart, via the pulmonary veins, and is pumped through the aorta to the rest of the body, including the heart muscle itself. With d-TGA, deoxygenated
4578159
Neuroeffector junction


of activity between cells. Many smooth muscle cells in a transverse section through a muscle bundle show regions of very close apposition to adjacent cells at which connexins form junctions between the cells. Unlike in cardiac muscle, where gap junctions are confined to the ends of cardiac myocytes, smooth muscle gap junctions occur along the length of the muscle cells as well as towards their ends. There are small bundles of three to seven varicose axons, partially or wholly enveloped in Schwann-cell sheath, both on the surface of the muscle as
10809412
TLN1


discs of cardiac muscle and to costamere structures of both skeletal and cardiac muscles, in correspondence with the I-band and M-line. Talin-1 is also found at focal adhesions of smooth muscle cells and non-muscle cells. In undifferentiated cultures of myoblasts, talin-1 expression is perinuclear, and then progresses to a cytoplasmic distribution followed by a sarcomlemmal, costameric-like pattern by day 15 of differentiation. Homozygous disruption of "TLN1" in mice is embryonic lethal, demonstrating that talin-1 is required for normal embryogenesis. It has
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Ryanodine receptor 2


the major component of a calcium channel located in the sarcoplasmic reticulum that supplies ions to the cardiac muscle during systole. To enable cardiac muscle contraction, calcium influx through voltage-gated L-type calcium channels in the plasma membrane allows calcium ions to bind to RYR2 located on the sarcoplasmic reticulum. This binding causes the release of calcium through RYR2 from the sarcoplasmic reticulum into the cytosol, where it binds to the C domain of troponin, which shifts tropomyosin and allows the myosin ATPase to bind to actin, enabling cardiac muscle contraction
6185433
MYH10


Myosin-10 also known as myosin heavy chain 10 or non-muscle myosin IIB (NM-IIB) is a protein that in humans is encoded by the "MYH10" gene. Non-muscle myosins are expressed in a wide variety of tissues, but NM-IIB is the only non-muscle myosin II isoform expressed in cardiac muscle, where it localizes to adherens junctions within intercalated discs. NM-IIB is essential for normal development of cardiac muscle and for integrity of intercalated discs. Mutations in MYH10 have been identified in
20652083
Cardiac muscle


likened to the wall of a house. Most of the wall is taken up by bricks, which in cardiac muscle are individual cardiac muscle cells or cardiomyocytes. The mortar which surrounds the bricks is known as the extracellular matrix, produced by supporting cells known as fibroblasts. In the same way that the walls of a house contain electrical wires and plumbing, cardiac muscle also contains specialised cells for conducting electrical signals rapidly (the cardiac conduction system), and blood vessels to bring nutrients to the muscle cells and take away waste products
1020156
GLUT4


-negative vesicles are activated by insulin stimulation as well as by exercise. Cardiac muscle is slightly different from skeletal muscle. At rest, they prefer to utilize fatty acids as their main energy source. As activity increases and it begins to pump faster, the cardiac muscles begin to oxidize glucose at a higher rate. An analysis of mRNA levels of GLUT1 and GLUT4 in cardiac muscles show that GLUT1 plays a larger role in cardiac muscles than it does in skeletal muscles. GLUT4, however, is still believed to be the primary
19737092
Central nervous system disease


the peripheral nervous system. It also conducts motor information to the body's skeletal muscles, cardiac muscles, smooth muscles, and glands. There are 31 pairs of spinal nerves along the spinal cord, all of which consist of both sensory and motor neurons. The spinal cord is protected by vertebrae and connects the peripheral nervous system to the brain, and it acts as a "minor" coordinating center. The brain serves as the organic basis of cognition and exerts centralized control over the other organs of the body. The brain
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Striated muscle tissue


organs such as the intestines or blood vessels. The fibers of striated muscle have a cylindrical shape with blunt ends, whereas those in smooth muscle can be described as being spindle-like with tapered ends. Two other characteristics that differentiate striated muscle from smooth muscle are that the former has more mitochondria and contains cells that are multinucleated. The main function of striated muscle tissue is to create force and contract. These contractions will either pump blood throughout the body (cardiac muscle) or powers breathing, movement or posture (skeletal muscle
20033134
Cardiac muscle cell


Cardiac muscle cells or cardiomyocytes (also known as myocardiocytes or cardiac myocytes) are the muscle cells (myocytes) that make up the cardiac muscle (heart muscle). Each myocardial cell contains myofibrils, which are specialized organelles consisting of long chains of sarcomeres, the fundamental contractile units of muscle cells. Cardiomyocytes show striations similar to those on skeletal muscle cells. Unlike multinucleated skeletal cells, the majority of cardiomyocytes contain only one nucleus, although they may have as many as four. Cardiomyocytes have a high mitochondrial density, which allows
14383732
Neocardiogenesis


scale repair, made necessary by events such as myocardial infarctions. Neocardiogenesis replaces dead cardiac muscle cells with living cells so that both the structure and function of the heart are maintained. This improves myocardial pumping of fluid around the body. The human heart has been thought of as a postmitotic organ. Cardiomyocytes (muscle cells of the heart) were thought to be terminally differentiated cells that were irreplaceable and thus required to maintain cardiac function throughout life. However it is now known that the heart is able to regenerate new small vessels needed
11121189
Cardiac physiology


that pump blood through the body. The pacemaker cells make up just (1% of cells) and form the conduction system of the heart. They are generally much smaller than the contractile cells and have few of the myofibrils or myofilaments which means that they have limited contractibility. Their function is similar in many respects to neurons. The bundle of His and Purkinje fibres are specialised cardiomyocytes that function in the conduction system. Cardiomyocytes, are considerably shorter and have smaller diameters than skeletal myocytes. Cardiac muscle (like skeletal muscle)
1157508
Cardiac arrest


death is expected. Sudden cardiac arrest (SCA) and sudden cardiac death (SCD) occur when the heart abruptly begins to beat in an abnormal or irregular rhythm (arrhythmia). Without organized electrical activity in the heart muscle, there is no consistent contraction of the ventricles, which results in the heart's inability to generate an adequate cardiac output (forward pumping of blood from heart to rest of the body). There are many different types of arrhythmias, but the ones most frequently recorded in SCA and SCD are ventricular
15053978
Anatomy


oesophagus, respiratory airways, and blood vessels. Cardiac muscle is found only in the heart, allowing it to contract and pump blood round the body. Nervous tissue is composed of many nerve cells known as neurons which transmit information. In some slow-moving radially symmetrical marine animals such as ctenophores and cnidarians (including sea anemones and jellyfish), the nerves form a nerve net, but in most animals they are organized longitudinally into bundles. In simple animals, receptor neurons in the body wall cause a local reaction to a
71933
Sarcocystis


lesions (oedema, hemorrhages, and necrosis) develop in the affected tissues. The parasite has a predilection for skeletal muscle (myositis), cardiac muscle (petechial hemorrhages of cardiac muscle and serosae), and lymph nodes (oedema, necrosis, and hemorrhage). These lesions are associated with maturation of second generation of meronts within the endothelial and subendothelials cells. Occasionally mononuclear infiltration or hyperemia has been observed in the lamina propria of the small intestine. After the acute phase, cysts may be found in various muscular tissues,
2746953
Cardiac muscle


both the atria and the ventricles of the heart. Although this muscle tissue is very similar between cardiac chambers, some differences exist. The myocardium found in the ventricles is thick to allow forceful contractions, while the myocardium in the atria is much thinner. The individual myocytes that make up the myocardium also differ between cardiac chambers. Ventricular cardiomyocytes are longer and wider, with a denser T-tubule network. Although the fundamental mechanisms of calcium handling are similar between ventricular and atrial cardiomyocytes, the calcium transient is smaller and decays more
1020175
Hooded seal


differently. Studies show that cardiac blood flow provides sufficient O2 to sustain lipolytic pathways during dives, remedying their hypoxic challenge. Cardiac tissue is found to be more developed than skeletal muscles at birth and during the weaning period, although neither tissue is fully developed by the end of the weaning period. Pups are born with fully developed hemoglobin stores (found in blood), but their myoglobin levels (found in skeletal tissue) are only 25–30% of adult levels. These observations conclude that pup muscles are less able to sustain both
5901262
TNNT2


an isoelectric point (pI) of 4.88. It is the tropomyosin- binding and thin filament anchoring subunit of the troponin complex in cardiac muscle cells. TNNT2 gene is expressed in vertebrate cardiac muscles and embryonic skeletal muscles. Cardiac TnT is a 35.9 kDa protein composed of 298 amino acids. Cardiac TnT is the largest of the three troponin subunits (cTnT, troponin I (TnI), troponin C (TnC)) on the actin thin filament of cardiac muscle. The structure of TnT is asymmetric; the globular C-terminal
5967579
MYL4


fetal skeletal muscle, as well as fetal and adult cardiac atrial tissue. ALC-1 binds the neck region of muscle myosin in adult atria. Two alternatively spliced transcript variants encoding the same protein have been found for this gene. Relative to ventricular essential light chain VLC-1, ALC-1 has an additional ~40 amino-acid N-terminal region that contains four to eleven residues that are critical for binding actin and modulating myosin kinetics. ALC-1 is expressed very early in skeletal muscle and cardiac muscle development; two E-boxes and CArG box in
21295014
Cardiac glycoside


it to be widely used medicinally in the treatment of cardiac arrhythmias. Cardiac glycosides have long served as the main medical treatment to congestive heart failure and cardiac arrhythmia, due to their effects of increasing the force of muscle contraction while reducing heart rate. Heart failure is characterized by an inability to pump enough blood to support the body, possibly due to a decrease in the volume of the blood or its contractile force. Treatments for the condition thus focus on lowering blood pressure, so that the heart does not have to exert as
7538253
Fasciculation


A fasciculation, or muscle twitch, is a small, local, involuntary muscle contraction and relaxation which may be visible under the skin. Deeper areas can be detected by electromyography (EMG) testing, though they can happen in any skeletal muscle in the body. Fasciculations arise as a result of "spontaneous depolarization" of a lower motor neuron leading to the synchronous contraction of all the skeletal muscle fibers within a single motor unit. An example of normal spontaneous depolarization is the constant contractions of cardiac muscle, causing the heart to
6821396
Amlodipine


, a non-dihydropyridine. In turn, following treatment lasting a month, with amlodipine, cardiac output was significantly enhanced. Unlike verapamil which has efficacy in moderation of emotional arousal and reduces cardiac load without lowering cardiac output demands, amlodipine increases the cardiac output response concomitantly with increased functional cardiac load. Amlodipine is an angioselective [[calcium channel blocker]] and inhibits the movement of calcium ions into [[vascular smooth muscle]] cells and [[cardiac muscle cell]]s which inhibits the contraction of cardiac muscle and vascular smooth
4800440
Troponin


is a Ca-binding subunit, playing the main role in Ca dependent regulation of muscle contraction. TnT and TnI in cardiac muscle are presented by forms different from those in skeletal muscles. Two isoforms of TnI and two isoforms of TnT are expressed in human skeletal muscle tissue (skTnI and skTnT). Only one tissue-specific isoform of TnI is described for cardiac muscle tissue (cTnI), whereas the existence of several cardiac specific isoforms of TnT (cTnT) are described in the literature. No cardiac specific isoforms are
18674212
Cardiac muscle


, then a region of heart muscle may become permanently scarred and damaged. Heart muscle can also become damaged despite a normal blood supply. The heart muscle may become inflamed in a condition called myocarditis, most commonly caused by a viral infection but sometimes caused by the body's own immune system. Heart muscle can also be damaged by drugs such as alcohol, long standing high blood pressure or hypertension, or persistent abnormal heart racing. Specific diseases of heart muscle called cardiomyopathies can cause heart muscle to become abnormally thick (hypertrophic cardiomyopathy
1020178
Artificial cardiac pacemaker


device and replace it by simply unhooking the leads from the device to replace and hooking the leads to the new device. The possible complications, such as perforation of the heart wall, come from removing the lead{s} from the patient's body. The other end of a pacemaker lead is actually implanted into the heart muscle. In addition leads that have been implanted for a decade or two will usually have attachments to the patient's body at various places in the pathway from device to heart muscle since the human body tends to
2821007
Admittance and conductance in cardiac performance


by Y = G + G + iωC where The signals G and C are both properties of cardiac muscle and vary in a fixed ratio. Thus the ratio of G to C is equal to the ratio of muscle conductivity (σ) to muscle permittivity (ε). The ratio σ/ε is the constant of proportionality. Although both σ and ε are functions of the health of the heart tissue, they are relatively constant for short periods of time. Using this proportionality, one can rewrite the equation for G as
6337403
Ventricular fibrillation


cardiac arrest. The ventricular muscle twitches randomly rather than contracting in a co-ordinated fashion (from the apex of the heart to the outflow of the ventricles), and so the ventricles fail to pump blood around the body – because of this, it is classified as a cardiac arrest rhythm, and patients in V-fib should be treated with cardiopulmonary resuscitation and prompt defibrillation. Left untreated, ventricular fibrillation is rapidly fatal as the vital organs of the body, including the heart, are starved of oxygen, and as
14144241
MYL2


Myosin regulatory light chain 2, ventricular/cardiac muscle isoform (MLC-2) also known as the regulatory light chain of myosin (RLC) is a protein that in humans is encoded by the "MYL2" gene. This cardiac ventricular RLC isoform is distinct from that expressed in skeletal muscle (MYLPF), smooth muscle (MYL12B) and cardiac atrial muscle (MYL7). Ventricular myosin light chain-2 (MLC-2v) refers to the ventricular cardiac muscle form of myosin light chain 2 (Myl2). MLC-2v is a 19-KDa protein composed
20906869
Cardiac yoga


the cardiovascular problems that cardiac yoga is aimed to relieve are coronary artery disease, hypertension, myocardial infarction, bypass surgery, and many others. Cardiac yoga is recommended to the medically stable patients. Cardiac yoga focuses mainly on breathing practices, stress reduction, stretching, relaxation, and body awareness techniques. While exercising, patients use mats, pillows, chairs and other accessories to ensure general comfort and correct positioning. The aim is to improve lung capacity, reduce stress, strengthen tired muscles and inspire healing. It also assists with
7401963
Cardiac muscle


such as collagen and elastin along with polysaccharides (sugar chains) known as glycosaminoglycans. Together, these substances give support and strength to the muscle cells, create elasticity in cardiac muscle, and keep the muscle cells hydrated by binding water molecules. The matrix in immediate contact with the muscle cells is referred to as the basement membrane, mainly composed of type IV collagen and laminin. Cardiomyocytes are linked to the basement membrane via specialised glycoproteins called integrins. The physiology of cardiac muscle shares many similarities with that of skeletal muscle. The
1020168
Calsequestrin


via presentation of a charged protein surface. Two forms of calsequestrin have been identified. The cardiac form Calsequestrin-2 (CASQ2) is present in cardiac and slow skeletal muscle and the fast skeletal form Calsequestrin-1(CASQ1) is found in fast skeletal muscle. The release of calsequestrin-bound calcium (through a calcium release channel) triggers muscle contraction. The active protein is not highly structured, more than 50% of it adopting a random coil conformation. When calcium binds there is a structural change whereby the alpha-helical content of the protein
15529099
Prenylamine


. Prenylamine has two primary molecular target in human, Calmodulin and Myosin light-chain kinase 2 found in skeletal and cardiac muscle. Pharmacologically, it decreases the sympathetic stimulation on cardiac muscle predominantly through partial depletion of catecholamine via competitive inhibition of reuptake by storage granule, which lead to further depletion due to spontaneous leakage as a result of disturbance of equilibrium. This depletion mechanism is similar to reserpine because both agents target the same site on storage granule, however prenylamine shows a high affinity for cardiac tissue while reserpine is more selective toward
16288035
John Alexander MacWilliam


. He found that there was a "certain area along the septum" where inhibition of the wave of contraction could be easily produced. He observed the condition which became known as "auricular flutter", and concluded that fibrillation was a disorder of muscle, not of nerve. He also described the basic elements of cardiopulmonary resuscitation - commonly abbreviated as CPR - (ventilation and cardiac compression) in keeping his experimental animals alive. His contributions to cardiac electrophysiology were not limited to ventricular fibrillation. For example, he described the technique
9789879
Nemaline myopathy


until adulthood. These cases are usually not genetic. Of the genes that have been linked to nemaline myopathy, most are also involved in encoding proteins in the sarcomeres in the muscle cells. Respiratory muscles are often more affected than other skeletal muscle groups. Cardiac muscle is usually not affected in nemaline myopathy patients and the ocular muscles are usually spared. The different genes whose mutations lead to the different kinds of nemaline myopathies affect the cells and the person’s body differently. The first kind of nemaline myopathy identified is due to the
9466780
Systole


other. First, atrial contraction feeds blood into the ventricles, then ventricular contraction pumps blood out of the heart to the body systems, including the lungs for resupply of oxygen. Cardiac systole is the contraction of the cardiac muscle in response to an electrochemical stimulus to the heart's cells (cardiomyocytes). Cardiac output (CO) is the volume of blood pumped by the left ventricle in one minute. The ejection fraction (EF) is the volume of blood pumped divided by the total volume of blood in the left ventricle
11206411
Cardiac fibrosis


Cardiac fibrosis may refer to an abnormal thickening of the heart valves due to inappropriate proliferation of cardiac fibroblasts but more commonly refers to the excess deposition of extracellular matrix in the cardiac muscle. Fibrotic cardiac muscle is stiffer and less compliant and is seen in the progression to heart failure. The description below focuses on a specific mechanism of valvular pathology but there are other causes of valve pathology and fibrosis of the cardiac muscle. Fibrocyte cells normally secrete collagen, and function to provide structural support for the heart. When over-activated this
10224813
ACTC1


ACTC1 encodes cardiac muscle alpha actin. This isoform differs from the alpha actin that is expressed in skeletal muscle, ACTA1. Alpha cardiac actin is the major protein of the thin filament in cardiac sarcomeres, which are responsible for muscle contraction and generation of force to support the pump function of the heart. Cardiac alpha actin is a 42.0 kDa protein composed of 377 amino acids. Cardiac alpha actin is a filamentous protein extending from a complex mesh with cardiac alpha-actinin (ACTN2) at Z-lines towards the center of the
19818299
MYL3


Myosin essential light chain (ELC), ventricular/cardiac isoform is a protein that in humans is encoded by the "MYL3" gene. This cardiac ventricular/slow skeletal ELC isoform is distinct from that expressed in fast skeletal muscle (MYL1) and cardiac atrial muscle (MYL4). Ventricular ELC is part of the myosin molecule and is important in modulating cardiac muscle contraction. Cardiac, ventricular ELC is 21.9 kDa and composed of 195 amino acids (See human MYL3 sequences features here). Cardiac ELC and the second light
21216317
Cardiac muscle


muscle including angina pectoris and myocardial infarction, and other heart muscle disease known as cardiomyopathies. Cardiac muscle tissue or myocardium forms the bulk of the heart. The heart wall is a three layered structure with a thick layer of myocardium sandwiched between the inner endocardium and the outer epicardium (also known as the visceral pericardium). The inner endocardium lines the cardiac chambers, covers the cardiac valves, and joins with the endothelium that lines the blood vessels that connect to the heart. On the outer aspect of the myocardium is the epicardium
1020153
Cardiac cycle


depleted blood to the lungs through the pulmonary trunk and arteries; or the systemic circulation—in which the left ventricle pumps/ejects newly oxygenated blood throughout the body via the aorta and all other arteries. In a healthy heart all activities and rests during each individual cardiac cycle, or heartbeat, are initiated and orchestrated by signals of the heart's electrical conduction system, which is the "wiring" of the heart that carries electrical impulses throughout the body of cardiomyocytes, the specialized muscle cells of the heart. These impulses ultimately
1599640
Brain-body interaction


Various types of brain-body interactions have been distinguished. For example, brain-gut interactions are biochemical signaling that takes place between the gastrointestinal tract and the central nervous system. Brain-heart interactions link cardiac physiology to activity in the central and peripheral nervous system and may explain how peripheral cardiovascular arousal can influence decision making and the regulation of social and emotional behaviours. Brain-muscle interactions involve both efferent nerve fibres that transmit action potentials to the muscles to generate muscle contractions and afferent nerve fibres that transmit somatosensory information back to
857779
Cytoskeletal drugs


as well as enhancing its rate of depolymerization. Typically the microtubule targeting drugs can be found in the clinic where they are used therapeutically in the treatment of some forms of cancer. As a result of the lack of specificity for specific type of actin (i.e. cannot distinguish between cardiac, smooth muscle, muscle and cytoskeletal forms of actin) the use of these drugs in animals results in unacceptable off target effects. Despite this the actin targeting compounds are still useful tools that can be used on a cellular level to help further
5881964
Myofilament


Myofilaments are the filaments of myofibrils, constructed from proteins, principally myosin or actin. Types of muscle are striated muscle (such as skeletal muscle and cardiac muscle), obliquely striated muscle (found in some invertebrates), and smooth muscle. Various arrangements of myofilaments create different muscles. Striated muscle has transverse bands of filaments. In obliquely striated muscle, the filaments are staggered. Smooth muscle has irregular arrangements of filaments. There are three different types of myofilaments: thick, thin, and elastic filaments. The protein complex composed
5382936
Antiarin


felines is 0.094 mg/kg, using intravenous injection. Meanwhile, 1 mg will kill a dog. β-Antiarin is administered to the body through injection. Once inside the body, the chemical will affect muscular and cardiac tissues. A heart attack occurs because beta-antiarin affects Na+K+-ATPase cardiac-muscle membrane activity. However, the very effect that allows β-antiarin to be a poison also gives it medicinal properties. It limits the sodium ion (Na) concentration by blocking the Na pump, which then promotes calcium
19149344
MYOM2


immunoglobulin C2-type repeats in the N-terminal region, five fibronectin type III repeats in the central region, and an additional four immunoglobulin C2-type repeats in the C-terminal region. M-protein is expressed only in striated muscle, including fast skeletal muscle and cardiac muscle. M-protein exhibits a different pattern of expression in cardiac and skeletal muscle, as well as fast- versus slow-skeletal muscle during development, suggesting different regulatory mechanisms for expression quantity and temporal appearance. In cardiac muscle, expression of M-protein continues
19570029
Striated muscle tissue


failure. Mammals have the ability to complete small amounts of cardiac regeneration during development. Vertebrates can regenerate cardiac muscle tissue throughout their entire life span. Skeletal muscle is able to regenerate far better than cardiac muscle due to satellite cells, which are dormant in all healthy skeletal muscle tissue. There are three phases to the regeneration process. These phases include the inflammatory response, the activation, differentiation, and fusion of satellite cells, and the maturation and remodeling of newly formed myofibrils. This process begins with the necrosis of damaged muscle
20033137
Congenital generalized lipodystrophy


(excessive hairiness) and hypertriglyceridemia. Fatty liver and muscle hypertrophy arise from the fact that lipids are instead stored in these areas; whereas in a healthy individual, lipids are distributed more uniformly throughout the body subcutaneously. The absence of adipose tissue where they normally occur causes the body to store fat in the remaining areas. Common cardiovascular problems related to this syndrome are cardiac hypertrophy and arterial hypertension (high blood pressure). This disorder can also cause metabolic syndrome. Most with the disorder also have a prominent umbilicus or umbilical hernia
21929139
Cardiac excitation-contraction coupling


at a rate between 60 and 100 beats every minute, when the body is at rest. This rate can be altered, however, by nerves that work to either increase heart rate (sympathetic nerves) or decrease it (parasympathetic nerves), as the body's oxygen demands change. Ultimately, muscle contraction revolves around a charged atom (ion), calcium (Ca), which is responsible for converting the electrical energy of the action potential into mechanical energy (contraction) of the muscle. This is achieved in a
14747273
Cardiac muscle cell


, they cannot be replaced, thus causing permanent damage. Current research indicates, however, that it may be possible to repair damaged cardiac tissue with stem cells. The cardiomyopathies are a group of diseases characterized by disruptions to cardiac muscle cell growth and / or organization. Presentation can range from asymptomatic to sudden cardiac death. Cardiomyopathy can be caused by genetic, endocrine, environmental, or other factors. Significant damage to cardiac muscle cells is referred to as myocytolysis. It was first described in medical literature by Schlesinger and Reiner
14383740
Cardiac contractility modulation


between the interior of the cell and its outside environment increased the calcium influx through the cell membrane and improved the contraction of cardiac muscle cells. In 2001, scientists observed that a similar effect occurs even if the voltage is applied exclusively outside the cardiac muscle cells. Additionally, it was observed that therapeutically useful effects on the cardiac muscle were achieved if the electrical signals were applied not only to single cells but to large areas using larger leads, as used in conventional cardiac pacemakers. The contractility of both a healthy heart and a
8926662
Cardiac contractility modulation


synchronized with the electrical action in the cardiac cycle. Other than a pacemaker, which delivers an electrical signal with the intention to result in cardiac contraction, the Cardiac contractility modulation treatment applies the NES, adjusted to and synchronized with the electrical action in the cardiac cycle. In Cardiac contractility modulation therapy, electrical stimulation is applied to the cardiac muscle during the absolute refractory period. In this phase of the cardiac cycle, electrical signals cannot trigger new cardiac muscle contractions, hence this type of stimulation is known as a non-
8926635
Cardiac muscle


primary function of both muscle types is to contract, and in both cases a contraction begins with a characteristic flow of ions across the cell membrane known as an action potential. The action potential subsequently triggers muscle contraction by increasing the concentration of calcium within the cytosol. However, the mechanism by which calcium concentrations within the cytosol rise differ between skeletal and cardiac muscle. In cardiac muscle, the action potential comprises an inward flow of both sodium and calcium ions. The flow of sodium ions is rapid but very short-lived,
1020169
Integrin beta 1


cardiac muscle and skeletal muscle, the integrin beta-1D isoform is specifically expressed, and localizes to costameres, where it aids in the lateral force transmission from the Z-discs to the extracellular matrix. Abnormal levels of integrin beta-1D have been found in limb girdle muscular dystrophy and polyneuropathy. Integrin beta-1 can exist as different isoforms via alternative splicing. Six alternatively spliced variants have been found for this gene which encode five proteins with alternate C-termini. Integrin receptors exist as heterodimers, and greater than 20 different integrin heterodimeric receptors have been
17775026
Dementia with Lewy bodies


autonomic dysfunction are often subtle. Symptoms include blood pressure problems, such as dizziness after quickly standing up and supine hypertension; constipation, urinary problems, and sexual dysfunction; loss of or reduced ability to smell; and excessive sweating, drooling, or salivation, and problems swallowing. Alpha-synuclein deposits can affect cardiac muscle and blood vessels. According to of the cardiac sympathetic nerves is a neuropathological feature" of the Lewy body dementias. Almost all people with synucleinopathies have cardiovascular dysfunction, although most are asymptomatic; individuals with DLB
6492064
Desmosome


A desmosome (; "binding body"), also known as a macula adherens (plural: maculae adherentes) (Latin for "adhering spot"), is a cell structure specialized for cell-to-cell adhesion. A type of junctional complex, they are localized spot-like adhesions randomly arranged on the lateral sides of plasma membranes. Desmosomes are one of the stronger cell-to-cell adhesion types and are found in tissue that experience intense mechanical stress, such as cardiac muscle tissue, bladder tissue, gastrointestinal
5160420
Telethonin


Z1-Z2 domains in cardiac and skeletal muscle. Structural analysis of full-length Telethonin with the N-terminal region of Titin indicate that the C-terminus of Telethonin is critical for the dimerization of two Telethonin/Titin complexes into a higher oligomeric structure. Telethonin expression is developmentally regulated in both cardiac and skeletal muscle and is thought to be critical to sarcomere assembly. Telethonin was found to be a late assembling protein only present in mature myofibrils at Z-discs. Telethonin forms a complex with MLP at Z-discs, which
20596561
Intercalated disc


Intercalated discs are microscopic identifying features of cardiac muscle. Cardiac muscle consists of individual heart muscle cells (cardiomyocytes) connected by intercalated discs to work as a single functional organ or syncytium. By contrast, skeletal muscle consists of multinucleated muscle fibers and exhibit no intercalated discs. Intercalated discs support synchronized contraction of cardiac tissue. They occur at the Z line of the sarcomere and can be visualized easily when observing a longitudinal section of the tissue. Three types of cell junction make up an intercalated disc — fascia adherens, desmosomes and gap
19662704
Cardiomyoplasty


Cardiomyoplasty is a surgical procedure in which healthy muscle from another part of the body is wrapped around the heart to provide support for the failing heart. Most often the latissimus dorsi muscle is used for this purpose. A special pacemaker is implanted to make the skeletal muscle contract. If cardiomyoplasty is successful and increased cardiac output is achieved, it usually acts as a bridging therapy, giving time for damaged myocardium to be treated in other ways, such as remodeling by cellular therapies. Cellular cardiomyoplasty is a method which augments myocardial function and
11565973
Aerospace physiology


because there is little or no oxygen. The work capacity of the body is reduced, decreasing the movement of all muscles (skeletal and cardiac muscles). The decrease in work capacity is related to the decrease of the oxygen of transportation velocity. Some acute effects from hypoxia include: dizziness, laxity, mental fatigue, muscle fatigue and euphoria. These effects will affect a non-acclimated person starting in an altitude of 3650 meters above sea level. These effects will increase and can result in cramps or convulsions at an altitude
14520371
Fibrodysplasia ossificans progressiva


skeletal bone. The diaphragm, tongue, and extra-ocular muscles are spared in this process, as well as cardiac and smooth muscle. Since the incorrect enzyme remains unresolved within the immune response, the body continues providing the incorrect BMP4-containing lymphocytes. BMP4 is a product that contributes to the development of the skeleton in the normal embryo. The ACVR1 gene encodes a bone morphogenic protein (BMP) receptor; this gene is mutated in FOP. It is responsible for growth and development of bone and muscles. The typical mutation,
16065949
Cardiac muscle


measuring 100–150μm by 30–40μm. Individual cardiac muscle cells are joined together at their ends by intercalated disks to form long fibres. Each cell contains myofibrils, specialised protein fibres that slide past each other. These are organised into sarcomeres, the fundamental contractile units of muscle cells. The regular organisation of myofibrils into sarcomeres gives cardiac muscle cells a striped or striated appearance when looked at through a microscope, similar to skeletal muscle. These striations are caused by lighter I bands composed mainly of a protein called actin, and darker A bands composed
1020158
Troponin


known for human TnC. TnC in human cardiac muscle tissue is presented by an isoform typical for slow skeletal muscle. Another form of TnC, fast skeletal TnC isoform, is more typical for fast skeletal muscles. cTnI is expressed only in myocardium. No examples of cTnI expression in healthy or injured skeletal muscle or in other tissue types are known. cTnT is probably less cardiac specific. Expression of cTnT in skeletal tissue of patients with chronic skeletal muscle injuries has been described. Inside the cardiac troponin complex the strongest interaction between molecules has
18674213
Heart


many respects to neurons. Cardiac muscle tissue has autorhythmicity, the unique ability to initiate a cardiac action potential at a fixed rate—spreading the impulse rapidly from cell to cell to trigger the contraction of the entire heart. There are specific proteins expressed in cardiac muscle cells. These are mostly associated with muscle contraction, and bind with actin, myosin, tropomyosin, and troponin. They include MYH6, ACTC1, TNNI3, CDH2 and PKP2. Other proteins expressed are MYH7 and LDB3 that are also expressed in skeletal muscle. The
16207065
Frank–Starling law


the sarcoplasmic reticulum. In addition, there is a decrease in the spacing between thick and thin filaments, when a cardiac muscle fiber is stretched, allowing an increased number of cross-bridges to form. The force that any single cardiac muscle fiber generates is related to the sarcomere length at the time of muscle cell activation by calcium. The stretch on the individual fibers, caused by ventricular filling, determines the sarcomere length of the fibres. Therefore the force (pressure) generated by the cardiac muscle fibres is related to the
18736276
TNNT2


Cardiac muscle troponin T (cTnT) is a protein that in humans is encoded by the "TNNT2" gene. Cardiac TnT is the tropomyosin-binding subunit of the troponin complex, which is located on the thin filament of striated muscles and regulates muscle contraction in response to alterations in intracellular calcium ion concentration. The TNNT2 gene is located at 1q32 in the human chromosomal genome, encoding the cardiac muscle isoform of troponin T (cTnT). Human cTnT is an ~36-kDa protein consisting of 297 amino acids including the first methionine with
5967578
Cardiac muscle


the network, enabling the syncytium to act in a coordinated contraction of the myocardium. There is an atrial syncytium and a ventricular syncytium that are connected by cardiac connection fibres. Electrical resistance through intercalated discs is very low, thus allowing free diffusion of ions. The ease of ion movement along cardiac muscle fibers axes is such that action potentials are able to travel from one cardiac muscle cell to the next, facing only slight resistance. Each syncytium obeys the all or none law. Intercalated discs are complex adhering structures that connect the
1020162