A muscle's capacity to be shortened is limited by
A) bones, which eventually impede further contraction.
B) the amount of overlap of actin and myosin, which eventually causes myosin to push against the Z line.
C) the amount of overlap of actin and myosin, which eventually causes actin to push against the Z line.
D) the water component of its fibers' cytoplasm, which is incompressible.
E) the water content of the cartilage matrix of the joint the muscle is associated with.

Question

Quizplus · Accepted Answer

The amount of overlap of actin and myosin in a muscle fiber is limited by the position of the Z line. When a muscle contracts, the actin filaments slide over the myosin filaments, causing the muscle to shorten. However, eventually the myosin filaments will push against the Z line, which restricts further shortening of the muscle fiber. Therefore, the capacity of a muscle to be shortened is limited by the amount of overlap between actin and myosin.

A Muscle's Capacity to Be Shortened Is Limited by