Membránpotenciálja

Membránpotenciálja 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, such as sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl-), across the cell membrane. The cell membrane is selectively permeable, meaning it allows certain ions to pass through more easily than others, primarily through ion channels and pumps.

The resting membrane potential is the stable electrical potential difference across the membrane of a neuron or muscle cell when it is not stimulated. This resting potential is typically negative inside the cell relative to the outside, often in the range of -70 millivolts. This negativity is largely due to the higher concentration of potassium ions inside the cell and the greater permeability of the membrane to potassium ions compared to sodium ions. Sodium-potassium pumps actively transport sodium ions out of the cell and potassium ions into the cell, contributing to the maintenance of these concentration gradients and thus the resting membrane potential.

Changes in membrane potential are crucial for cellular communication and function, particularly in excitable cells like neurons and muscle cells. When a cell is stimulated, ion channels can open or close, altering the permeability of the membrane to specific ions. This leads to a rapid change in the membrane potential, known as an action potential. Action potentials are essential for nerve impulse transmission and muscle contraction. The precise value and dynamics of the membránpotenciálja are fundamental to these physiological processes.