Question

Where in a myelinated axon are nearly all of the ion channels concentrated?

1) the cell body
2) nodes of Ranvier
3) dendrites
4) axon terminals
5) neuron nucleus

Answer 1

Option 2.

In myelinated neurons, nearly all ion channels are concentrated at the nodes of Ranvier, which facilitates rapid signal transmission through saltatory conduction.

Step-by-step explanation:

In the structure of a myelinated neuron, nearly all of the ion channels are concentrated at the nodes of Ranvier.

These nodes are critical gaps in the myelin sheath produced by glial cells, allowing for the rapid propagation of nerve impulses down the axon.

This occurs through a process known as saltatory conduction, where the action potential signal jumps from node to node rather than traveling continuously down the axon.

This is due to the clustering of sodium (Na+) and potassium (K+) ion channels at these nodes, which are absent in the myelinated sections of the axon.

Thus, the correct option in the final answer to where nearly all of the ion channels are concentrated in a myelinated axon is option 2: nodes of Ranvier.