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Action Potential (continued)

The action potential may then be seen to be generated by the sequential opening and closing of voltage gated Na channels which will transiently depolarize the cell membrane and then allow it to return to the resting potential. As the Na channels inactivate K channels activate moving the membrane potential closer to the K equilibrium potential than at rest. This repolarizes the cell rapidly in the face of substantial membrane capacitance and serves to reactivate Na channels after closing of the H gate.

 

The action potential transmits information from point to point within and without the central nervous system by the sequential activation of ion channels along its length. Speed of transmission depends on the decay of signal along the axon with distance, which in turn depends on the relative resistances of the membrane around the axon and the axial resistance along the cytoplasm inside the axon. Thus either insulating the axon with myelin or increasing the diameter of the axons will increase transmission speeds.
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