What is the process called when the membrane potential returns to -90 mV?

What is the process called when the membrane potential returns to -90 mV?

• A. Repolarization
• B. Depolarization
• C. Hyperpolarization
• D. Resting potential restoration

Answer: (A)

Returning to the negative resting value after a depolarizing event is repolarization. In heart muscle cells, the resting membrane potential sits around -90 mV. After depolarization, the interior becomes less negative, and then potassium channels open to let K+ exit the cell. This outward current drives the membrane potential back toward the negative resting level. Once it reaches roughly -90 mV, the cell is back at its resting state. If the membrane went even more negative, that would be hyperpolarization, not simply returning to rest. The term resting potential restoration isn’t the standard label—the process is repolarization.

Returning to the negative resting value after a depolarizing event is repolarization. In heart muscle cells, the resting membrane potential sits around -90 mV. After depolarization, the interior becomes less negative, and then potassium channels open to let K+ exit the cell. This outward current drives the membrane potential back toward the negative resting level. Once it reaches roughly -90 mV, the cell is back at its resting state. If the membrane went even more negative, that would be hyperpolarization, not simply returning to rest. The term resting potential restoration isn’t the standard label—the process is repolarization.