kalvonjännitteeseen

Kalvonjännitteeseen refers to the electrical potential difference across a biological membrane, most commonly the plasma membrane of a cell. This potential difference arises due to an unequal distribution of ions across the membrane, primarily sodium (Na+), potassium (K+), chloride (Cl-), and calcium (Ca2+). The cell membrane is selectively permeable, allowing some ions to pass through channels more readily than others.

The resting membrane potential is the electrical potential difference across the plasma membrane of a neuron or other excitable cell when it is not actively stimulated. This potential is typically negative inside the cell relative to the outside, usually in the range of -60 to -90 millivolts. This negative charge is maintained by the sodium-potassium pump, which actively transports sodium ions out of the cell and potassium ions into the cell, and also by the passive diffusion of ions down their electrochemical gradients.

Changes in membrane potential are crucial for cellular communication, particularly in nerve and muscle cells. When a stimulus causes the membrane potential to become less negative (depolarization) or more positive (repolarization), it can trigger electrical signals such as action potentials. These rapid changes in membrane potential are fundamental to processes like nerve impulse transmission and muscle contraction. The magnitude and duration of these voltage changes are tightly regulated by the opening and closing of voltage-gated ion channels.