What is the primary function of myelin in the nervous system?

The primary function of myelin in the nervous system is to insulate nerve fibers and enhance the speed of electrical signal transmission. Myelin is a fatty substance that surrounds the axons of many neurons, forming a protective sheath. This myelin sheath is crucial for efficient conduction of electrical impulses along the nerve fibers.

When an electrical signal, or action potential, travels down a myelinated axon, it jumps between the nodes of Ranvier—gaps in the myelin sheath—rather than traveling continuously along the nerve fiber. This jumping mechanism, known as saltatory conduction, greatly increases the speed at which signals are propagated, allowing for rapid communication between different parts of the nervous system.

In contrast to the other functions listed, providing nutrients to neurons, generating electrical impulses, or forming the blood-brain barrier are not roles served by myelin. Myelin does not supply nutrients; those are delivered by other means, such as blood supply to the neurons. While neuronal cell membranes are indeed involved in generating electrical impulses, myelin itself does not generate them; it merely facilitates the speed and efficiency of their transmission. Additionally, the blood-brain barrier is primarily formed by endothelial cells of blood vessels in the brain, with myelin having no