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Axons can range in length from a fraction of an inch to several feet,

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but they all have the same function: to carry messages to other cells.

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How does the neuron send its signal down the axon?

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Axonal conduction is a complicated electrical-chemical process.

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In simplest terms, it involves an electrical impulse that travels down the axon like a wave.

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Every time an impulse travels down the axon, we say that the axon has "fired," or "responded."

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This impulse is also called the action potential.

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Let's enlarge a portion of the axon to get a closer view of this process.

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To understand how impulses travel, you need to know that some molecules can pass easily through the membrane,

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while others can only pass through special channels controlled by gates.