Myelin Sheath

The myelin sheath is a protective covering that surrounds nerve fibers (axons) in the nervous system. It is made up of a type of glial cell called oligodendrocytes in the central nervous system (CNS) and Schwann cells in the peripheral nervous system (PNS).

Structure of the Myelin Sheath

The myelin sheath is composed of multiple layers of lipid-rich membrane that wrap around the axon of a neuron. These layers provide insulation and support for the nerve fiber, allowing for the rapid transmission of electrical impulses along the axon.

Function of the Myelin Sheath

The primary function of the myelin sheath is to increase the speed and efficiency of nerve impulse conduction. By insulating the axon, the myelin sheath helps to prevent the loss of electrical signals and allows for saltatory conduction, in which the action potential "jumps" from one node of Ranvier to the next, speeding up the transmission of nerve impulses.

Importance of Myelin Sheath

Damage or loss of the myelin sheath can result in a range of neurological disorders, such as multiple sclerosis (MS), in which the immune system attacks and destroys the myelin in the CNS. This can lead to impaired nerve function and communication, causing symptoms such as muscle weakness, numbness, and coordination problems.

Study Guide

1. Define the myelin sheath and describe its composition.
2. Explain the role of oligodendrocytes and Schwann cells in the formation of the myelin sheath.
3. Discuss the function of the myelin sheath in speeding up nerve impulse conduction.
4. Identify the difference between myelinated and unmyelinated axons in terms of impulse conduction.
5. Explore the consequences of myelin sheath damage and its association with neurological disorders.

Understanding the structure and function of the myelin sheath is crucial for comprehending the mechanisms of nerve impulse transmission and the impact of myelin-related disorders on the nervous system.