Membranpotenzialänderungen

Membranpotenzial, also known as membrane potential, refers to the difference in electrical potential that exists across the plasma membrane of cells. This potential difference is primarily established by the unequal distribution of ions, such as sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl-), across the cell membrane. The cell membrane is selectively permeable, allowing some ions to pass through more easily than others via ion channels and pumps.

The resting membrane potential, the potential difference across the membrane when a cell is not actively signaling, is typically negative inside relative to the outside. This negativity is largely due to the outward movement of potassium ions, driven by their concentration gradient and the action of the sodium-potassium pump, which actively transports sodium ions out of the cell and potassium ions into the cell.

Changes in membrane potential are fundamental to cellular function, particularly in excitable cells like neurons and muscle cells. Depolarization occurs when the membrane potential becomes less negative or more positive, often due to the influx of positive ions. Repolarization is the return of the membrane potential to its resting state after depolarization. Hyperpolarization occurs when the membrane potential becomes more negative than the resting potential. These dynamic changes in membrane potential are the basis of electrical signaling in the body, enabling nerve impulse transmission and muscle contraction.