What would probably happen if a long neuron had one continuous myelin sheath down the length of the axon with no nodes of Ranvier?
A) The action potential would be propagated nearly instantaneously to the synapse.
B) There could be no action potential generated at the axon hillock.
C) The signal would fade because it is not renewed by the opening of more sodium channels.
D) The action potential would be propagated normally to the synapse.

Question

Quizplus · Accepted Answer

Nodes of Ranvier are important for the renewal of the action potential because they contain a high density of sodium channels that allow for rapid depolarization of the membrane. Without these nodes, the signal would progressively fade as it travels down the axon since the sodium channels would not be renewed. Therefore, if a myelin sheath covered the entire length of a long neuron, the absence of nodes of Ranvier would result in a fading signal, and not rapid propagation to the synapse (A) or normal propagation to the synapse (D). Additionally, the absence of nodes of Ranvier would not prevent the generation of an action potential at the axon hillock (B).

What Would Probably Happen If a Long Neuron Had One