Action potential

Definition

An action potential is a rapid rise and subsequent fall in voltage or membrane potential across a cellular membrane. It is the fundamental mechanism by which neurons communicate and transmit information.

5 Must Know Facts For Your Next Test

1. Action potentials are initiated when a neuron receives a sufficient stimulus to exceed the threshold potential.
2. They follow an all-or-none principle, meaning they either occur fully or not at all.
3. The phases of an action potential include depolarization, repolarization, and hyperpolarization.
4. Sodium (Na+) and potassium (K+) ions play crucial roles in generating and propagating action potentials.
5. Myelinated axons conduct action potentials faster than unmyelinated axons due to saltatory conduction.

Review Questions

• What triggers the initiation of an action potential in a neuron?
• Describe the all-or-none principle in relation to action potentials.
• How do sodium and potassium ions contribute to the phases of an action potential?

Related terms

Depolarization: The process during which the cell's membrane potential becomes less negative, moving towards zero.

Repolarization: The process by which the cell's membrane potential returns to its resting negative value after depolarization.

Threshold Potential: The critical level to which a membrane potential must be depolarized to initiate an action potential.