Figure 17-38 shows an electron micrograph of a skeletal muscle fiber, where various points along a fiber and various regions have been labeled. Figure 17-38
Which of the following statements is TRUE about muscle contraction?

Question

Figure 17-38 shows an electron micrograph of a skeletal muscle fiber, where various points along a fiber and various regions have been labeled.  Figure 17-38
Which of the following statements is TRUE about muscle contraction?

Quizplus · Accepted Answer

According to the sliding filament theory of muscle contraction, the overlapping actin and myosin filaments slide past each other, causing the sarcomere (region between two Z lines) to shorten. Therefore, as the muscle fiber contracts, point B (located at the center of the sarcomere) will move closer to point C (located at the Z line), while point A (located at the opposite end of the sarcomere) will also move closer to point B. Region D (the H zone, located in the center of the A band) will become smaller as the actin filaments slide inward, but region E (the I band, located between two adjacent A bands) will not necessarily shrink in size.

Figure 17-38 Shows an Electron Micrograph of a Skeletal Muscle