Membránpotenciálok

Membránpotenciálok refer to the electrical potential difference across a biological membrane, particularly the plasma membrane of cells. This potential difference arises due to the uneven distribution of ions between the intracellular and extracellular environments. Key ions involved include sodium (Na+), potassium (K+), chloride (Cl-), and calcium (Ca2+).

The resting membrane potential is the stable potential difference across the membrane of a non-excited cell. It is primarily established by the selective permeability of the membrane to different ions, mediated by ion channels, and the action of the sodium-potassium pump, which actively transports ions against their concentration gradients. In most animal cells, the resting membrane potential is negative inside relative to the outside, typically ranging from -60 to -80 millivolts.

Changes in membrane potential are crucial for cell function. For excitable cells like neurons and muscle cells, these changes can lead to action potentials. Depolarization, a decrease in the magnitude of the membrane potential (making the inside less negative), and repolarization, a return to the resting potential, are fundamental processes in nerve impulse transmission and muscle contraction. Hyperpolarization, an increase in the magnitude of the membrane potential (making the inside more negative), can also occur. The precise values and dynamics of membrane potentials are vital for a wide range of physiological processes.