An era is a commonly used word for a long period of time. When used in science, for example geology, an era denotes a clearly defined period of time of arbitrary but well-defined length, such as for example the Mesozoic Era from 252 Maâ66 Ma, delimited by a start event and an end event.
As you increase voltage to the muscle describe how it responds to the increased stimulus. As the voltage was increased from threshold to maximum voltage, there was a greater force in the muscle contraction. Once the maximum voltage (2500 mv) was reached, even if there was an increase in voltage, the force of the muscle contraction remained the same.
At lengths less than about 70% of resting length, the muscle develops no tension at all when stimulated. It follows that, during an isotonic contraction, a skeletal muscle can only shorten to about 70% of its resting length, and it can only develop tension at lengths between 70% and 180% of resting length.ecause all of the muscle fibers of a motor unit contract simultaneously, it is more difficult to achieve fine gradations in the force of contraction when motor units are large. Suppose one motor unit contains 20 fibers and another only 5, and suppose each fiber can produce 1 gram of force.