repolarizáció

Repolarizáció refers to the change in membrane potential that returns it to a negative value after having been depolarized. This process is crucial in the function of excitable cells, particularly neurons and muscle cells, where it follows an action potential. During depolarization, the cell membrane becomes more permeable to positive ions, such as sodium (Na+), causing the inside of the cell to become positive relative to the outside.

Following depolarization, repolarization occurs as the ion permeability of the membrane shifts again. Typically, the influx of sodium ions is rapidly terminated, and the outward movement of potassium (K+) ions increases significantly. This outward flow of positive charge makes the inside of the cell negative once more, restoring the resting membrane potential. The precise ionic mechanisms and timing of repolarization can vary depending on the specific type of cell and the physiological context. In some cases, a period of hyperpolarization, where the membrane potential becomes even more negative than the resting potential, may precede the full restoration of the resting state. This sequence of depolarization, repolarization, and sometimes hyperpolarization is fundamental to the propagation of electrical signals in the nervous system and the contraction of muscle tissue.