Final answer:
During repolarization, voltage-gated sodium channels close and potassium channels open, allowing for the restoration of the cell's resting potential. This involves the outflow of K+ ions, which results in the cell's interior becoming more negative. The sodium-potassium ATPase pump plays a critical role in maintaining the resting potential.
Step-by-step explanation:
During repolarization, the process by which a neuron or muscle cell returns to its resting state after depolarization, certain events occur in the ion channels within the cell membrane. Initially, the voltage-gated sodium channels close to stop the influx of Na+ ions, which had caused the membrane to depolarize. Subsequently, potassium channels open, allowing K+ ions to exit the cell. This efflux of positively charged potassium ions causes the inside of the cell to be more negatively charged once again, leading to the return of the membrane potential towards the resting level.
However, there is often a slight overshoot, known as hyperpolarization, because potassium channels close with a delay, making the inside of the cell even more negative than the normal resting potential temporarily. The ongoing activity of the sodium-potassium ATPase pump, which continually moves Na+ out of the cell and K+ back into the cell, helps maintain the resting potential after the potassium channels eventually close and the refractory period ends, reestablishing the -70 mV resting membrane potential.