When a depolarizing graded potential makes the axon membrane depolarize to threshold, A) ligand-gated Ca⁺² channels close rapidly. B) voltage-gated Ca⁺² channels open rapidly. C) ligand-gated Na⁺ channels close rapidly. D) voltage-gated Na⁺ channels open rapidly. E) none of these choices.

Question

Quizplus · Accepted Answer

When the axon membrane depolarizes to threshold, voltage-gated Na⁺ channels open rapidly, initiating an action potential.

When a Depolarizing Graded Potential Makes the Axon Membrane Depolarize