depolarizációt

Depolarizáció refers to a change within a cell, particularly a neuron, where the cell membrane's electrical potential becomes less negative. This is a crucial process in the transmission of nerve impulses. Normally, a neuron's resting membrane potential is negative, maintained by the unequal distribution of ions across the cell membrane. When a stimulus, such as a neurotransmitter binding to a receptor, causes positive ions, primarily sodium (Na+), to flow into the cell, the interior of the neuron becomes less negative. This influx of positive charge reduces the charge difference across the membrane.

If the depolarization reaches a certain threshold level, it triggers a much larger and rapid influx of sodium ions, leading to a dramatic reversal of the membrane potential. This event is known as an action potential, which is the fundamental unit of electrical signaling in the nervous system. The action potential then propagates along the neuron, allowing for communication between nerve cells. Following depolarization, a repolarization phase occurs, where the membrane potential returns to its negative resting state, typically facilitated by the outflow of potassium (K+) ions. Depolarization is also a key event in muscle contraction and other physiological processes involving electrical signaling.