What Are the Functions of Myelin Sheath?

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The body’s central nervous system generates a continuous flow of nerve impulses through a network of neurones. Neurones, or nerve cells, are designed to conduct electrical impulses from one nerve to another at rapid-fire rates. Myelin sheaths make it possible for impulses to travel as fast as they do and help to protect nerve cell fibers in the process.

Impulse Transmission

Impulse transmissions enable movement, thought, digestion and several other functions to take place in the body. According to the Partners in Assistive Technology Training and Services, myelin sheaths make it possible for impulses to travel quickly across the body’s network of nerve cells. The body houses millions of neurones that work to transmit information to and from the brain. These cells come equipped with a nucleus body, dendrite extensions and nerve fibers and are specifically designed to conduct electrical impulses throughout the body. Electrical impulses travel across nerve fibers in much the same way that electricity travels through wires. Myelin sheaths appear as a lipid, or a fat-like material that covers nerve fibers. Their physical make-up helps electrical impulses move faster when compared to nerve cells that don’t have coverings.

Protective Covering

Within the peripheral nervous system, glial cells manufacture myelin sheaths using sheets of membrane extensions that reach across the axon portions of a nerve cell, according to Eastern Kentucky University. Nerve cells appear in segments, or internodes, with short gaps interspersed along a line. Myelin sheaths act as an insulation covering for electrical signals as signals move through a line of nerve cells. Cells can appear in groups with one cell running alongside another. According to the Gondar Design Science reference site, myelin sheaths enable each individual cell to transmit signals without interference from neighboring cells. Nerve cells located in the brain and spinal cord lack myelin sheaths and are referred to as “grey matter,” while the myelin-covered nerves within the peripheral system take on the name “white matter,” as the fatty myelin sheaths give them a white appearance.

Signal Conduction

Electrical signals move through long lines of nerve cells by hopping from one cell to the next. According to Eastern Kentucky University, the Nodes of Ranvier that appear in between successive cells work like small signal conduction stations that use the myelin coverings to jump electrical signals from cell to cell. This process works through a series of chemical reactions that take place at the node junctions. The dendrite extensions have small storage vesicles that release neurotransmitter chemicals into the gap. These chemicals alert the next cell that an electrical impulse is on its way. Since the myelin sheaths acts as insulators, they have a high electrical resistance. The neurotransmitters released into the node attract electrical energy, which causes electrical signals to jump from node to node rather than travel the entire length of the axon.

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