Jämviktsspänningen

Jämviktsspänningen is a Swedish term that translates to equilibrium potential or equilibrium voltage. It refers to the electrical potential difference across a membrane at which there is no net movement of a specific ion. This condition is achieved when the electrical force acting on the ion is exactly balanced by the chemical force (concentration gradient) driving the ion across the membrane.

The concept of jämviktsspänningen is fundamental in understanding the electrical activity of cells, particularly neurons and muscle cells. It is calculated using the Nernst equation, which considers the charge of the ion, the temperature, and the extracellular and intracellular concentrations of that ion. For a specific ion, its jämviktsspänningen represents the theoretical voltage that would drive the ion towards equilibrium if it were the only permeable ion.

In biological membranes, multiple ions are typically permeable to varying degrees. The actual membrane potential at rest or during an action potential is a weighted average of the jämviktsspänningar for all permeable ions, determined by their relative permeabilities. Changes in the permeability of the membrane to specific ions, such as during the opening or closing of ion channels, can shift the membrane potential towards the jämviktsspänningen of the ion that has become more permeable. Therefore, jämviktsspänningen is a key parameter for predicting and explaining how membrane potentials change in response to physiological stimuli.