Osmosis video - Action potentials in myocytes

An action potential (AP) is a voltage change that propagates along the membrane of a myocyte (muscle cell) or other cells such as a nerve cell. The AP is generated by the movement of positively charged ions, mainly Na+ and K+, across the plasma membrane. This generates an electrical current that travels down the length of the myocyte.

The AP triggers the release of Ca2+ from intracellular stores, which in turn activates contractile proteins within the myocyte. This ultimately leads to muscle contraction.