Which term describes the restoration of the resting membrane potential after depolarization?

• A. Repolarization
• B. Depolarization
• C. Hyperpolarization
• D. Polarization

Answer: (A)

Restoration of the resting membrane potential after depolarization is repolarization. During depolarization, Na+ channels open and Na+ enters the cell, making the inside less negative. To return to the baseline resting potential, voltage-gated K+ channels open and K+ exits, driving the membrane potential back toward negative values. The Na+/K+ pump and leak channels then help reestablish and maintain the resting gradient. Hyperpolarization would occur if the membrane becomes more negative than resting after the initial return, and depolarization refers to the initial rise in positivity, not the return to rest. Polarization is just the presence of a potential difference, not the process of restoring it.