How does demyelination affect nerve conduction velocity?

Demyelination refers to the loss or damage of the myelin sheath, which is a protective covering that surrounds nerve fibers. This myelin sheath is crucial for the proper conduction of electrical impulses along the nerves. When myelin is intact, it allows for faster communication between nerve cells through a process known as saltatory conduction. In this process, electrical impulses jump from one node of Ranvier (the gaps in the myelin sheath) to another, significantly increasing the speed of conduction.

When demyelination occurs, the insulating properties of the myelin are compromised, leading to several consequences. The conduction velocity of electrical impulses decreases because the impulses can no longer jump as efficiently between the nodes, resulting in a slower overall transmission of signals. This slower conduction velocity can lead to various neurological symptoms, such as weakness, numbness, and impaired motor function, depending on the extent and location of the demyelination.

The correct answer highlights the direct impact of demyelination on nerve conduction velocity, showing that the vital role of myelin in facilitating rapid signal transmission is disrupted, ultimately leading to a slower conduction velocity.