What is repolarization?

What is repolarization?

• A. Membrane becomes more positive
• B. Membrane returns to negative
• C. Membrane becomes more negative than resting
• D. Membrane remains depolarized

Answer: (B)

Repolarization is the phase of an action potential when the membrane potential returns toward the negative resting value after depolarization. As the spike peaks, voltage-gated Na+ channels inactivate and K+ channels open, allowing K+ to exit the cell. This outward current makes the inside more negative, driving the membrane back from a positive peak toward the resting potential (often dipping briefly below resting, then stabilizing). So the best description is that the membrane returns to negative. Depolarization would be the membrane becoming more positive, hyperpolarization would be briefly more negative than resting, and remaining depolarized would mean it hasn’t returned to rest.

Repolarization is the phase of an action potential when the membrane potential returns toward the negative resting value after depolarization. As the spike peaks, voltage-gated Na+ channels inactivate and K+ channels open, allowing K+ to exit the cell. This outward current makes the inside more negative, driving the membrane back from a positive peak toward the resting potential (often dipping briefly below resting, then stabilizing). So the best description is that the membrane returns to negative. Depolarization would be the membrane becoming more positive, hyperpolarization would be briefly more negative than resting, and remaining depolarized would mean it hasn’t returned to rest.