試題詳解

3. How do myelin sheaths increase the speed with which action potentials are propagated along an axon?

(A) They increase the permeability of Na+ ions in the plasma membrane.

(B) They amplify the action potential by increasing sodium influx along the entire distance of the neuron.

(C) They insulate the axon, preventing K+ ions from exiting the neuron.

(D) They cause action potentials to "jump" down the axon rather than travel in a continuous path along every site on the axon.