Question

A sarcomere is ________?

1) the nonfunctional unit of skeletal muscle
2) the area between two Z discs
3) the area between two intercalated discs
4) the wavy lines on the cell seen in the microscope

Answer 1

The sarcomere is the functional unit of a skeletal muscle, defined as the region between two consecutive Z lines. It contains overlapping actin and myosin filaments, and its contraction results in the shortening of the muscle fiber, facilitating movement.

Step-by-step explanation:

A sarcomere is the functional unit of a skeletal muscle fiber. It is defined as the region from one Z line to the next Z line. Within this region, the sarcomere encompasses one whole A band, which contains myosin and actin filaments that overlap, and two half I bands, each containing just the actin filament, which are anchored to the Z lines. The Z lines demarcate the boundaries of the sarcomere, and contraction occurs as the actin and myosin filaments slide over one another, leading to the shortening of the sarcomere and, consequently, muscle contraction.

The structure contributes to the striated pattern observed in skeletal muscles, with regular alternating dark (A bands) and light (I bands) giving the muscle its characteristic striped appearance. As myofibrils, composed of many sarcomeres, contract, the muscle cells contract, enabling movement.