MCAT Content / Specialized Cell Nerve Cell / Myelin Sheath Schwann Cells Insulation Of Axon

Myelin sheath, Schwann cells, insulation of axon

Topic: Specialized Cell Nerve Cell

Schwann cells, specialized neuroglia cells, produce myelin sheath, which acts as insulation along the axon.

Most mammalian neurones are coated in a whitish, fatty layer called the myelin sheath (not part of the neuron.) It insulates the nerve fibers to prevent signal loss or crossing of signals. Just like insulation prevents wires next to each other from accidentally discharging each other. In addition, myelin increases the speed of conduction in the axon. Schwann cells are neuroglia cells that form the myelin sheath.  

Neuron: The myelin sheath surrounds and insulates the axon.

 

Practice Questions

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MCAT Official Prep (AAMC)

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Key Points

• A whitish, fatty layer called the myelin sheath (not part of the neuron) acts as insulation of axon, prevents loss or crossing of neural signals, and increases the speed of conduction in the axon.

• Schwann cells are specialized neuroglia cells that support neuronal function by increasing the speed of impulse propagation; they produce the myelin sheath


Key Terms

myelin: a substance produced by cells of the neuroglia that increases the speed of impulses along the axon of the neuronal fibre

neuroglia: supporting cells in nervous tissue

myelin sheath: acts to protect the nerves from other electrical impulses, and speeding the time it takes for a nerve to traverse an axon

Schwann cells: glial cells that support nerve regeneration

node of Ranvier: a small constriction in the myelin sheath of axons



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