Depolarization

Depolarization, in biology, refers to a sudden change within a cell, during which the cell undergoes a dramatic electrical change. Most cells, especially those that compose the tissues of highly organized animals, typically maintain an internal environment that is negatively charged compared to the cell's surrounding environment. This difference in charge is called the cell's membrane potential. In the process of depolarization, the negative internal charge of the cell becomes positive for a very brief time. This shift from a negative to a positive internal cellular environment allows for the transmission of electrical impulses both within a cell and, in certain instances, between cells. This communicative function of depolarization is essential to the function of many cells, communication between cells, and the overall function of an organism.

Physiology

The process of depolarization is entirely dependent upon the intrinsic electrical nature of most cells. When a cell is at rest, the cell maintains what is known as a resting potential. The resting potential generated by nearly all cells results in the interior of the cell having a negative charge compared to the exterior of the cell. To maintain this electrical imbalance, microscopic positively and negatively charged particles called ions are transported across the cell's plasma membrane. The transport of the ions across the plasma membrane is accomplished through several different types of transmembrane proteins embedded in the cell's plasma membrane that function as pathways for ions both into and out of the cell, such as ion channels, sodium potassium pumps, and voltage gated ion channels.