Nerve Conduction Board Practice Test

Myelin is a fatty insulating layer that surrounds the axons of many neurons. The presence of myelin significantly increases the conduction velocity of nerve impulses. This occurs because myelinated axons conduct action potentials via a process known as saltatory conduction. In this process, the action potential jumps between the nodes of Ranvier—gaps in the myelin sheath—rather than propagating continuously along the entire axon membrane. This jumping mechanism allows for much faster transmission of action potentials compared to unmyelinated axons, where the entire axon membrane must depolarize sequentially.

Additionally, the myelin sheath reduces the leakage of ions across the axonal membrane, which helps maintain the electrical signal within the axon and leads to a more efficient conduction process. Thus, myelin substantially enhances the speed at which electrical signals travel along the axon, making the statement that it increases conduction velocity substantially true.

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