The event(s) that induce the contraction of a muscle fiber is/are the
A) entry of calcium ions into the cytoplasm of the muscle fiber.
B) entry of chloride ions into the cytoplasm of the muscle fiber.
C) release of acetylcholine onto the postsynaptic membrane.
D) separation of the actin and myosin filaments.
E) movement of potassium ions into the muscle fiber.

Question

Quizplus · Accepted Answer

The entry of calcium ions into the cytoplasm of the muscle fiber is the event that induces the contraction of a muscle fiber. Calcium ions bind to a protein called troponin, which causes tropomyosin to shift and expose binding sites on the actin filaments for myosin heads to attach and initiate the sliding of the actin and myosin filaments.

The Event(s) That Induce the Contraction of a Muscle Fiber