müüliini

Müüliini is a substance found in the human body that plays a crucial role in the nervous system. It is a fatty insulating material that forms a protective sheath around nerve fibers, similar to the insulation around an electrical wire. This sheath is called the myelin sheath.

The primary function of the myelin sheath is to speed up the transmission of nerve impulses. Without it, signals would travel much slower, impairing coordination, sensation, and cognitive functions. The myelin sheath is not continuous along the entire length of a nerve fiber. Instead, it is interrupted at regular intervals by gaps known as nodes of Ranvier. These nodes are critical for efficient nerve impulse conduction, allowing the electrical signal to "jump" from one node to the next, a process called saltatory conduction.

Myelin is produced by specialized cells. In the central nervous system (brain and spinal cord), these cells are called oligodendrocytes, while in the peripheral nervous system (nerves outside the brain and spinal cord), they are called Schwann cells. These cells wrap their membranes around the axon, forming multiple layers that constitute the myelin sheath.

Demyelination, the loss or damage of the myelin sheath, can have severe consequences. Diseases like multiple sclerosis are characterized by the progressive destruction of myelin in the central nervous system, leading to a wide range of neurological symptoms. Research continues to explore ways to protect and repair myelin to treat such conditions.