When an action potential arrives at the muscle fiber, calcium is released internally and binds with troponin.

Question

Quizplus · Accepted Answer

This statement is true. When an action potential arrives at the muscle fiber, calcium is released internally from the sarcoplasmic reticulum (a specialized type of endoplasmic reticulum found in muscle fibers) and binds with troponin, a protein found on the actin filaments of the muscle fiber. This binding causes tropomyosin to shift, exposing the binding sites on the actin filament, allowing for myosin to form cross-bridges and initiate muscle contraction.

When an Action Potential Arrives at the Muscle Fiber, Calcium