Explain the difference in the speed of conduction of an action potential along the length of a myelinated neurone and a non-myelinated neurone.

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First, we need to explain how the action potential is conducted along the length of the axon.

An action potential is transferred along an axon by the movement of Na+ and K+ ions into and out of the cell. These are controlled by voltage-gated Naand K+ channels. 

When the neuron is stimulated, the voltage-gated Na+ ion channels open, causing Na+ ions to flood into the cell. There is a positive charge inside the cell and a negative charge outside.

This change in charge causes K+ channels to open and Na+ channels to close. K+ ions diffuse out and the charge builds up so that there is a positive charge outside the cell and a negative charge inside.

This change in charge again causes the Na+ channels to open and the K+ channels to close. This occurs like a wave along the length of the axon and the signal travels away.

We also need to look at the soidum potassium pump. In an non-myelinated neuron these will occur along the entire length of the axon. Whereas, in a myelinated neuron, these occur in the gaps between Schwann cells which coat the axon.

In myelinated neurons this will occur by 'saltatory conduction' - so the action potential jumps between neurons. You can think of this like skipping, the signal travels faster by jumping a bit.

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