| Myelin sheath | |||||
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The myelin sheath is a covering that is around many long nerve fibres, which is made from a fatty, waxy substance that is white in colour.
The myelin sheath is in place to protect the nerve fibres from damage and to insulate them (just like electrical wiring).
The myelin sheath increases the rate at which nerve impulses can be sent.
- The part of the nerve fibre that is myelinated is the axon
- The myelin sheath allows electrical impulses to go extremely fast through the nerve fibres (compared to an unmyelinated nerve fibre)
- Myelinated nerve fibres are found in both the central nervous system (CNS) and peripheral nervous system (PNS)
- Multiple sclerosis is a "demyelinating illness", where the myelin sheath progressively disappears
Why myelin sheath is important?
The myelin sheath is really important as it allows nervous impulses to be sent through the nervous tissues (nerve fibres) in a coordinated and functional manner.
If the myelin sheath somehow gets worn away, or is not there, the nervous impulses cannot be sent through the nerve fibres properly and the result is an inability to to control muscles and mobility.
references
- Marieb EM, Hoehn K. Human Anatomy & Physiology. 7th edition, 2006. Benjamin Cummings Publishing
- Tortora GJ, Derrickson BH. Principles of Anatomy & Physiology. 11th edition, 2005. Wiley Publishing
To learn more, go to the following web sites:
- Baker Heart Research Institute (Australia)
- Northeast Valley of General Practice (Australia)
