myeliinikerroksena

Myeliinikerros, often referred to as the myelin sheath in English, is a fatty insulating layer that surrounds the axons of many nerve cells. This sheath is not a continuous covering but is segmented, with gaps called nodes of Ranvier. The myelin is produced by glial cells: Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system.

The primary function of the myelin sheath is to facilitate the rapid transmission of electrical impulses, known as action potentials, along the axon. It achieves this by acting as an insulator, preventing the leakage of electrical charge. In myelinated axons, the action potential "jumps" from one node of Ranvier to the next, a process called saltatory conduction. This significantly increases the speed of nerve impulse conduction compared to unmyelinated axons. This faster conduction is crucial for many bodily functions, including motor control, sensory perception, and cognitive processes.

Damage to the myelin sheath, a process known as demyelination, can have severe neurological consequences. Diseases like multiple sclerosis (MS) and Guillain-Barré syndrome involve the breakdown of myelin, leading to impaired nerve signal transmission and a range of debilitating symptoms. The composition of myelin is complex, consisting of lipids and proteins, and its integrity is vital for proper nervous system function.