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.

Question

Quizplus · Accepted Answer

Myelin sheaths cause action potentials to "jump" down the axon, a process known as saltatory conduction. This increases the speed of propagation because the action potential only needs to be regenerated at the nodes of Ranvier, where there is a high concentration of voltage-gated sodium channels, rather than propagating along the entire length of the axon. This conserves energy and speeds up the process of axial conduction.

How Do Myelin Sheaths Increase the Speed with Which Action