Final answer:
When the membrane potential exceeds VNa+, voltage-gated Na+ channels close, and K+ channels open, leading to repolarization and a return towards the resting membrane potential. This is followed by a phase of hyperpolarization before the cell returns to its resting state.
Step-by-step explanation:
The question pertains to the events that occur at the peak of an action potential within a nerve cell. When the membrane potential rises and exceeds the sodium equilibrium potential (VNa+), the voltage-gated sodium channels close, and the voltage-gated potassium channels open. As a result, potassium ions (K+) begin to leave the cell, driven by their concentration gradient. This outflow of positively charged potassium ions causes the cell's membrane potential to move back toward its resting state in a process known as repolarization.
Following repolarization, the cell may experience a brief period of hyperpolarization, where the membrane potential becomes even more negative than its typical resting potential. Eventually, the membrane potential stabilizes at its resting level, marking the end of the action potential. It is important to note that during the action potential's refractory period, the cell cannot fire another action potential until it returns to a stable resting state.