Action potential
An action potential is a regenerative change in membrane voltage, produced by time-dependent opening and inactivation of voltage-gated ion channels.
Open interactive lesson & self-check ↗Typical neuronal action potential
Original conceptual SVG · scalableIllustrative voltage-versus-time trace; not calibrated. Cardiac pacemaker cells have different mechanisms.
Resting state
Ion gradients, selective membrane permeability and active pumps support resting electrical potential; values vary by cell type.
Rising phase
In a typical excitable axon, reaching threshold opens voltage-gated sodium channels and sodium influx depolarizes the membrane.
Recovery phase
Sodium-channel inactivation and potassium conductance contribute to repolarization; refractory periods support directional propagation along normal pathways.
Reference and next reading
Explore the original curriculum and publisher-hosted resources for full-depth reading; this note is an original schematic introduction, not an exhaustive chapter.