The release of which of the following nutrients from extracellular fluid stimulates muscle contraction?
A) phosphorus
B) potassium
C) sodium
D) calcium

Question

Quizplus · Accepted Answer

Calcium is the nutrient released from extracellular fluid that stimulates muscle contraction. When a muscle is stimulated by a nerve impulse, calcium ions are released from the sarcoplasmic reticulum in the muscle cell. The calcium ions then bind to the protein complex troponin-tropomyosin, causing a shift in position that exposes the myosin binding sites on the actin filaments. This allows the myosin heads to bind to actin and initiate muscle contraction.

The Release of Which of the Following Nutrients from Extracellular