試題詳解

70. Action potentials are usually propagated in only one direction along an axon because
(A)ions can flow along the axon only in one direction.
(B) the brief refractory period prevents opening of voltage-gated Na⁺ channels.
(C)the nodes of Ranvier conduct only in one direction.
(D) the axon hillock has a higher membrane potential than the tips of the axon.

(E) both sodium and potassium vollage-gated channels open in one direction.