Myelin sheath

Definition

The myelin sheath is a fatty layer that surrounds the axons of neurons, providing insulation and increasing the speed of electrical signal transmission. It plays a crucial role in maintaining the proper functioning of the nervous system.

5 Must Know Facts For Your Next Test

1. Myelin sheaths are produced by oligodendrocytes in the central nervous system and Schwann cells in the peripheral nervous system.
2. Demyelination, or damage to the myelin sheath, can lead to severe neurological diseases such as multiple sclerosis.
3. The myelin sheath enhances signal conduction through saltatory conduction, where impulses jump between nodes of Ranvier.
4. Myelin is composed predominantly of lipids (about 70-80%) and proteins (about 20-30%).
5. Infections affecting the nervous system can result in inflammation that damages or disrupts the myelin sheath.

Review Questions

• What cells are responsible for producing myelin sheaths in the central and peripheral nervous systems?
• How does demyelination affect neural signal transmission?
• What role do nodes of Ranvier play in relation to the myelin sheath?

Related terms

Oligodendrocytes: Glial cells in the central nervous system responsible for forming and maintaining myelin sheaths.

Schwann Cells:

Cells in the peripheral nervous system that produce myelin sheaths around neuronal axons.

Demyelination: The process by which myelin sheaths are damaged, leading to disrupted neural signal transmission.