Which ion's movement is influenced by the membrane potential in cells?

The movement of potassium ions (K+) is significantly influenced by the membrane potential in cells due to their concentration gradient and the electrochemical gradient. The membrane potential, which is the difference in charge across the cell membrane, creates a driving force for potassium ions to move.

At rest, a cell typically has a negative membrane potential, making the interior of the cell more negative compared to the outside. This encourages K+ ions, which are usually more concentrated inside the cell, to move out as the membrane becomes more depolarized. Conversely, when the membrane potential becomes more positive, the electrochemical gradient decreases, influencing the movement of K+ ions back into the cell.

The role of K+ ions is vital in establishing and maintaining the resting membrane potential and in the repolarization phase of action potentials. This dynamic allows cells to respond to signals effectively, with K+ gradients playing a crucial role in nerve impulse transmission and muscle contraction.