What occurs when sodium channels open during depolarization?

When sodium channels open during depolarization, sodium ions enter the cell. This process is critical in the generation of action potentials in neurons and muscle cells. The opening of sodium channels allows sodium ions, which are more concentrated outside the cell than inside, to flow in due to both the concentration gradient and the electrical gradient. This influx of positive sodium ions causes the interior of the cell to become more positively charged, leading to a rapid depolarization of the membrane potential.

As this depolarization reaches a certain threshold, it can trigger further physiological processes, such as the firing of an action potential in neurons. This is a fundamental mechanism by which signals are transmitted in the nervous system and muscle contraction occurs. The options relating to potassium ions exiting the cell or the restoration of the resting membrane potential pertain to events that occur subsequently or differently in the action potential process, rather than being a direct result of sodium channel opening during depolarization.