Myeliinisoituja

Myeliinisoituja is a Finnish term that translates to "myelinated" in English. It refers to nerve fibers that are covered by a myelin sheath. This sheath is a fatty insulating layer that is produced by glial cells, specifically Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. The myelin sheath is not continuous but is interrupted at regular intervals called nodes of Ranvier.

The primary function of myelination is to increase the speed at which nerve impulses, also known as action potentials, travel along the axon. The myelin sheath acts as an electrical insulator, preventing the leakage of ions across the axonal membrane. This insulation allows the action potential to "jump" from one node of Ranvier to the next, a process called saltatory conduction. This significantly speeds up signal transmission compared to unmyelinated axons, where the action potential must propagate continuously along the entire length of the axon.

Myelination is a crucial process for the proper functioning of the nervous system. It enables rapid and efficient communication between different parts of the body, which is essential for complex behaviors such as movement, sensation, and thought. Diseases that affect myelin, such as multiple sclerosis, can lead to severe neurological deficits due to the disruption of nerve signal transmission. The process of myelination begins during fetal development and continues into adolescence and even early adulthood.