What is the function of the myelin sheath?

The myelin sheath serves the crucial function of insulating nerve fibers. It is a protective covering made of lipid (fatty) substances that surrounds the axons of many neurons. This insulation enables electrical impulses, or action potentials, to travel more quickly along the nerve fibers. The presence of the myelin sheath increases the speed of conduction of these impulses through a process called saltatory conduction, where the impulse jumps from one Node of Ranvier (the gaps in the myelin sheath) to another, allowing for faster communication between nerve cells.

In contrast, the roles of transmitting chemical signals, generating electrical impulses, and connecting neurons are attributed to different structures and processes within the nervous system. For instance, neurotransmitters are responsible for transmitting chemical signals at synapses, while the generation of electrical impulses occurs due to changes in membrane potential in the neuron itself rather than being a function of the myelin sheath. Thus, the primary and distinctive role of the myelin sheath lies in its insulating properties, which enhance the efficiency of neural signal transmission.