The absolute refractory period
What causes a neuron's absolute refractory period?
Answer D: explanation for every choice
A
The pump keeps running and isn't responsible for refractoriness.
B
Open K+ channels contribute to the relative refractory period, when a stronger stimulus can still fire the cell.
C
Refractory periods are a property of the axon membrane, not synaptic transmitter supply.
D
Correct. Inactivation gates block Na+ channels until repolarization resets them, so no stimulus can trigger another spike.
TakeawayAbsolute refractory: Na+ channels inactivated. Relative: K+ conductance still elevated.
Next question →
Reviewed 2026-11-05 by a medical student. Spot an error? Report it with question ID bb173.