What effect does an influx of Na+ have on a cell's membrane potential?

An influx of sodium ions (Na+) into a cell leads to depolarization of the membrane potential. This occurs because sodium is positively charged, and when it enters the cell, it increases the overall positive charge within the cell compared to the extracellular fluid. The resting membrane potential is typically negative due to the distribution of ions, particularly the higher concentration of potassium ions (K+) inside the cell and sodium ions outside.

When sodium channels open, allowing Na+ to flow into the cell, the membrane potential shifts toward a more positive value. This movement away from the negative resting potential signifies depolarization. If sufficient depolarization occurs, it can trigger an action potential, a critical process for the function of neurons and muscle cells.

In contrast, hyperpolarization refers to an increase in negativity of the membrane potential, stabilization suggests a maintenance of the membrane potential, and repolarization is the process of returning to resting potential after depolarization has occurred. These processes are distinct and do not directly result from the influx of Na+.