During which stage of the action potential are voltage-gated sodium channels closed?

The correct answer is that voltage-gated sodium channels are closed during the repolarization stage of the action potential. During repolarization, the membrane potential returns to a more negative value following depolarization. This occurs after the peak of the action potential when sodium channels, which had been open during depolarization allowing sodium ions to flow into the cell, begin to close.

As the cell membrane potential becomes more positive, the influx of sodium ions causes the cell to become depolarized. Once the peak is reached, voltage-gated sodium channels inactivate and close, preventing further sodium from entering the cell and initiating the repolarization process. At this time, voltage-gated potassium channels open, allowing potassium to exit the cell, which helps to bring the membrane potential back down towards its resting state.

In the resting state, sodium channels are typically closed, but repolarization is characterized specifically by the transition from a depolarized condition to a hyperpolarized condition, during which the inactivation of sodium channels is essential for the action potential's progression. Hyperpolarization follows repolarization but is more associated with the time when potassium channels are still open, allowing the membrane potential to overshoot the resting level briefly.

Thus