Neuroscience: A Journey Through the Brain
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The Structure of a Neuron: The Axon
The axon of the neuron conducts electrical signals. Two
features distinguish it from the soma:
1. No RER extends into the axon and there are few, if any, ribosomes. These means that no protein synthesis occurs in the axon.
2. The protein composition of the axon is fundamentally different from that of the soma membrane. The properties of the axonal membrane allow it to convey electrical signals.
Axons may extend anywhere from less than a millimeter to over a meter long. Axons that originate in and travel away from a particular neuron are termed efferents. Axons that travel towards and provide input to a particular neuron are termed afferents. Axons may often branch along their path, and these branches are termed axon collaterals.
Axons range in diameter from less than 1 micrometer to 25 micrometers in humans, and can be as large as 1 millimeter in the squid. Variation in axon size is important because the speed of conduction along an axon is partially dependant on the size of the axon. Generally, the fatter the axon, the faster a nerve impulse travels. Read more about nerve impulses in the Action Potential section.
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Last Updated: April 09, 2002 08:55 PM