Which process is primarily involved in the end of the action potential and the return to resting state?

Repolarization is the key process that involves returning the membrane potential of a neuron back to its resting state following an action potential. During an action potential, the depolarization phase occurs first, where sodium channels open, and sodium ions rush into the neuron, causing the inside of the cell to become more positive. Following this rapid depolarization, the cell must then return to its resting negative membrane potential.

Repolarization takes place when potassium channels open, allowing potassium ions to flow out of the neuron. This efflux of potassium contributes to reversing the change in voltage that occurred during depolarization. The membrane potential begins to return to the value observed during the resting state, which is typically around -70mV.

While hyperpolarization can occur, where the membrane potential becomes even more negative than the resting potential, it is a consequence of repolarization and may lead to a brief period where the membrane is less likely to fire another action potential. The refractory period refers to the time after an action potential during which the neuron is not responsive to further stimuli, but it is the process of repolarization that is primarily responsible for returning the neuron to its resting state after the action potential has peaked.