Final answer:
During repolarization, there is a closure of voltage-gated sodium channels and an opening of potassium channels, causing potassium to leave the cell and move the membrane potential back to the resting state. Plasma membrane sodium-potassium ATPase helps restore and maintain this resting potential.
Step-by-step explanation:
The significant change that happens to ion channels and ion movement during repolarization involves the closure of voltage-gated sodium channels and the opening of potassium channels. During the peak of depolarization, voltage-gated sodium channels close, preventing more sodium (Na+) from entering the cell. Meanwhile, voltage-gated potassium channels open, allowing potassium (K+) to leave the cell, carrying a positive charge with it. This outflow of potassium results in the cell's interior becoming negative again, moving the membrane potential back toward its resting state of approximately -70 mV. This process helps to restore the resting potential after the cell has undergone an action potential.
The plasma membrane sodium-potassium ATPase plays a crucial role, always actively transporting Na+ out of the cell and K+ into the cell, maintaining the resting state. Following repolarization, the cell enters a refractory period, during which it cannot generate another action potential immediately as the voltage-sensitive ion channels return to their resting configurations, preparing the cell for the next impulse.