Muscle fibers contract when Z lines move _________ and the sarcomeres _________.
A) apart;stretch
B) apart;shorten
C) together;stretch
D) together;shorten

Question

Quizplus · Accepted Answer

Muscle fibers contract when the Z lines move together (toward the center of the sarcomere) and the sarcomeres shorten. This is due to the myosin heads pulling on the actin filaments, causing them to slide past each other and the sarcomere to contract. Therefore, choice D ("together;shorten") is the best choice.

Muscle Fibers Contract When Z Lines Move _________ and the Sarcomeres