What occurs when K+ ions flow out of the cell after depolarization?

When potassium ions (K+) flow out of the cell after depolarization, this process is essential in returning the membrane potential back to its resting state, a process known as repolarization. During depolarization, the membrane potential becomes more positive as sodium ions (Na+) rush into the cell. Once the depolarization reaches a certain threshold, the voltage-gated sodium channels close, and the voltage-gated potassium channels open, allowing K+ ions to exit the cell.

As K+ ions move out, the positive charge within the cell decreases, causing the membrane potential to drop back toward a negative value, effectively moving it back towards the resting potential. This process is critical for the resetting of the neuron after an action potential, allowing it to be ready for subsequent depolarizations.

While hyperpolarization can occur if the membrane potential becomes more negative than the resting potential due to an excessive efflux of K+ or opening of other anion channels, the immediate event resulting directly from the outflow of K+ post-depolarization is specifically classified as repolarization. This physiological process is necessary for the proper functioning of neurons and muscle cells.