Question

Depolarization, the process by which muscle fibers are stimulated to contract, occurs when:

Answer 1

Answer:

C. cell wall permeability changes and sodium rushes into the cell.

Explanation:

During depolarization, there is a decrease in the charge difference across the membrane. The inside of the membrane becomes positive compared to the outside. During depolarization, the voltage-gated Na+ channels are opened rapidly. The electrochemical gradient favors the movement of Na+ towards the inside of the cell. The inward movement of Na+  causes the depolarizing phase of the action potential and changes the membrane potential from −55 mV to +30 mV.