Action Potential

An action potential is the rapid change in a neuron’s resting membrane potential that propagates electrical signals in the nervous system.

The typical resting potential of a neuron is about –70 millivolts, which can be altered by signals, such as neurotransmitters.

When the membrane potential becomes less negative, it depolarizes beyond the threshold potential value, triggering an action potential.

As a result, voltage-gated sodium channels open and sodium ions rush into the cell down their electrochemical gradient.

The positive ion influx raises the membrane potential to about +30 millivolts, marking the peak of the action potential.

The sodium channels then inactivate, and voltage-gated potassium channels open.

Potassium ions move down their concentration gradient. The membrane becomes less positive and repolarizes.

Briefly, the membrane potential dips below the resting potential, decreasing the chance of another action potential until the resting state is regained.