Question

Which statement accurately describes the myelin sheath?

a. It allows the nodes of Ranvier to act as an electrical insulator.
b. It is found on dendrites in the central nervous system and prevents crossing over of electrical impulses between the axons and the dendrites.
c. It prevents saltatory conduction.
d. It is found on all axons outside the brain and spinal cord (central nervous system).
e. It speeds up the conduction of nervous impulses.

A) Only e
B) All are correct
C) a, b, c only
D) b, c, d only

Answer 1

The myelin sheath insulates axons and speeds up the conduction of nervous impulses by enabling salutatory conduction, allowing electrical signals to leapfrog from one node of Ranvier to the next.

Step-by-step explanation:

The myelin sheath is a crucial structure of many neurons, providing insulation for the axon to ensure rapid transmission of electrical impulses. The statement e. It speeds up the conduction of nervous impulses accurately describes the function of the myelin sheath. The nodes of Ranvier enable salutatory conduction, allowing impulses to leapfrog from node to node, increasing the speed of transmission. The myelin sheath is not present on all axons outside the central nervous system and does not act as an insulator at the nodes of Ranvier; rather, it permits fast conduction along the axon itself while the nodes facilitate the recharging of the signal.