When Contraction Occurs, ________

Question

When contraction occurs, ________.
A) the A band remains constant
B) the H band gets smaller
C) the I band begins to disappear
D) the Z lines move closer together
E) All of the answers are correct.

Accepted Answer

During contraction, all of the given changes occur in the sarcomere. The A band remains constant and maintains the length of the thick filaments. The H band gets smaller as the thin filaments slide inward and overlap with the thick filaments. The I band begins to disappear as the thin filaments slide inward and the Z lines move closer together as the sarcomere shortens. Therefore, all of the answers are correct.