One change that occurs within a sarcomere during muscle contraction is that the
A) thin filaments get thicker.
B) thick filaments move closer together.
C) Z lines move closer together.
D) thick filaments get thicker.

Question

Quizplus · Accepted Answer

During muscle contraction, the sarcomere shortens as the Z lines move closer together. This occurs because the thin filaments slide past the thick filaments, causing the H zone (region in the middle of the sarcomere where only thick filaments are present) to shorten. The thick filaments do not get thicker and the distance between them does not change, so options A and D can be eliminated. Option B may seem plausible, but it is ultimately incorrect as it is not the thick filaments that move closer together, but rather the Z lines.

One Change That Occurs Within a Sarcomere During Muscle Contraction