- Action potential (also known as a nerve impulse or spike) is a pulse-
like wave of voltage that travels along several types of cell
membranes. The best-understood example is generated on the membrane of
the axon of a neuron, but also appears in other types of excitable
cells, such as cardiac muscle cells, and even plant cells. The resting
voltage across the axonal membrane is typically −70 millivolts (mV),
with the inside being more negative than the outside.