Oligodendrocytes - Location, Structure, and Function
Myelin sheaths are made of a fatty substance and insulate a nerve to increase its signal speed. In the peripheral nervous system (PNS) they are produced by Schwann cells, in the central nervous system (CNS) by oligodendrocytes.
- Each Schwann cell myelinates only a small portion (0.3 mm to 1.5 mm) of an axon.
- The minute gaps that occur between adjacent myelin sheaths are called nodes of Ranvier.
- In these areas, the axon is exposed to the surrounding environment and proteins embedded in the plasma membrane can produce action potentials (electrochemical impulses).
- Thus, when action potentials travel down a myelinated axon, they appear to jump from node to node.
- This process is termed saltatory conduction, and it is used to transfer information quickly, such as to and from the skeletal muscles.
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