What is the process called when the cell recharges back to its resting state?

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

Answer: (A)

Repolarization is the process of returning the cell to its resting membrane potential after depolarization. During depolarization, the cell’s interior becomes more positive as Na+ ions rush in. After the peak, Na+ channels inactivate and K+ channels open, allowing potassium to exit the cell. This outward flow of positive charge brings the membrane potential back toward the negative resting level. In cardiac cells there’s a brief plateau from Ca2+ influx, but the ongoing K+ outflow finishes repolarization, restoring the resting state. Hyperpolarization would push the membrane potential even more negative than resting, which is a separate phase that can follow repolarization. Threshold is the level needed to trigger an action potential, not the return to rest.