Definition of Myelin

Myelin is a protective covering that surrounds and insulates the nerve fibers in the central nervous system (CNS) and peripheral nervous system (PNS). It is composed of a mixture of proteins and lipids, forming a white, fatty substance that gives the characteristic appearance to the myelinated nerves.

Structure of Myelin

Myelin is formed by specialized cells called oligodendrocytes in the CNS and Schwann cells in the PNS. These cells wrap themselves around the axons of neurons, forming multiple layers of membrane sheets. The myelin sheath is segmented with tiny gaps called nodes of Ranvier, which play a crucial role in the conduction of nerve impulses.

Function of Myelin

The primary function of myelin is to increase the speed and efficiency of nerve impulse transmission. By insulating the nerve fibers, myelin prevents electrical signals from dissipating or getting lost along the axons. It facilitates the rapid conduction of impulses, allowing for quick and coordinated communication between different parts of the nervous system.

Importance of Myelin

Myelin is critical for normal neurological functioning. Proper functioning of the nervous system, including motor and sensory functions, largely depends on the presence of intact myelin. Any damage or degradation in myelin, such as in demyelinating disorders like multiple sclerosis, can severely disrupt nerve signal transmission and lead to various neurological symptoms and impairments.