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    Hi, guys!I'm in my AS year and I'm doing an assignment on the myelin sheath. Could someone help me out in terms of the formation and function of the sheath, like how it's made?I know that in the PNS the Schwann cells coat the axon and that forms the sheath but for the CNS, all I know is that oligodendrocytes make the sheath.If someone could hint or push me in the right direction for these questions, it would be awesome!What's the function of the myelin sheath?How is the sheath formed and the chemical composition?
    What si the effect of demyelination on the neurone?
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    I know that the function of the myelin sheath is to increase the speed at which the signal travels along the axon - from AS psych. From this I'd take a guess that the effect of demyelinated would be that the signal travels slower.

    In terms of how it's formed - just google it:
    for example: "The myelin sheath is formed as individual cells extend their plasma membranes around the axons of neurons in a spiral fashion. In the central nervous system, these are called oligodendroglial cells, while in the peripheral nervous system, they are called Schwann cells.
    https://www.reference.com/science/myelin-sheath-formed-2474970320af894 "

    demyelination: https://www.google.co.uk/webhp?sourc...=demyelination
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    I assume what you are being asked is to understand nerve impulses. An idea of your depth of knowledge, and desired detail, would be helpful. As you're in AS I shall assume that you are being guided towards understanding that myelin sheathes allow something called the Nodes of Ranvier. These nodes, allow something called saltatory conduction (the phrasing being derived from the latin for jump) as that is what happens. Instead of along a nerve continuously the action potential is propagated along at these nodes, allowing it to jump, thus being far quicker than normal conduction. This is useful for numerous reasons, for instance in reflex arcs it speeds up an already quick process.

    As such in answering your final question, a removal of this removes the benefits of it. In other words it slows conduction down dramatically. A condition you may consider that this involves is MS; there are also motor nerve diseases (ALS being the most common).

    In terms of structure and how it is made that sounds a little too complicated for AS. However, as you correctly said in the PNS it is Schwann cells that are responsible, and Oligodendrocytes in the CNS.
 
 
 
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