Question

Which statement accurately describes the myelin sheath? a. It speeds up the conduction of nervous impulses. 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 is found on all axons outside the brain and spinal cord (central nervous system). d. It prevents saltatory conduction. e. It allows the nodes of Ranvier to act as an electrical insulator

Answer 1

The myelin sheath is an insulating layer that surrounds nerve fibers and speeds up the conduction of nervous impulses.

Step-by-step explanation:

The myelin sheath is an insulating layer that surrounds nerve fibers, including axons, in the central and peripheral nervous systems. It consists of glial cells, such as Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. The myelin sheath helps to increase the speed of conduction of nerve impulses called action potentials.

By insulating the axon, the myelin sheath prevents dissipation of electrical signals and allows for saltatory conduction, where the action potential jumps from one node of Ranvier to another. This process speeds up the transmission of nerve impulses.

Therefore, statement a is correct: The myelin sheath speeds up the conduction of nervous impulses.

Learn more about myelin sheath