membránpotenciált

Membránpotenciált refers to the electrical potential difference that exists across the plasma membrane of a cell. This potential difference arises from the uneven distribution of ions between the intracellular and extracellular environments. The primary ions involved are sodium (Na+), potassium (K+), chloride (Cl-), and calcium (Ca2+).

The resting membrane potential is established and maintained by several factors. The selective permeability of the cell membrane to different ions, primarily due to the presence of ion channels, plays a crucial role. The sodium-potassium pump, an active transport mechanism, continuously works to move sodium ions out of the cell and potassium ions into the cell, against their respective concentration gradients. This pump is essential for maintaining the concentration gradients that drive ion movement through passive channels.

The concentration gradients of these ions, combined with their differential permeability across the membrane, result in a net negative charge inside the cell relative to the outside. This difference in electrical charge is the resting membrane potential, which is typically around -70 millivolts in many animal cells.

Changes in the membrane potential are fundamental to cellular function, particularly in excitable cells like neurons and muscle cells. Depolarization, a decrease in the magnitude of the membrane potential (making the inside less negative), and repolarization, a return to the resting potential, are key events in the generation and propagation of electrical signals, such as action potentials. Hyperpolarization, an increase in the magnitude of the membrane potential (making the inside more negative), also plays a role in regulating neuronal activity.