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    I'm having trouble getting my head around this, it doesn't really make any sense.

    I understand the Na-K pump, and its role in the resting potential. I get the Action potential, how the stimulus changes permeability of the axon membrane to Na+ ions, thus increasing the PD from -65 mV to +40 mV, and how when the channel closes and K+ ions flood out to stabilise the electrochemical balance to reach the original resting potential.

    But what I don't understand is how this whole sequence of action potential, can be transmitted across a neurone because the movement of ions is happening perpendicular to the supposed direction.

    This is what I think happens but I'm not 100% sure and if anyone could correct me, please do and explain.

    So the influx of Na+ ions inside the axon from the action potential, moves across the axon to a more negative potential area. This depolarises the surrounding negative area to positive due to the surge of Na+ down an electrochemical gradient. This then skips the stage of the action potential mechanism, where the permeability of Na+ ions is made available to diffuse them inside the axon, and goes straight into the stage where the K+ channels open to stabilise the electrochemical balance. So the same Na+ ions that flooded in from the first action potential move across the whole axon to the end.

    Any help, much appreciated.
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    http://highered.mcgraw-hill.com/site...__quiz_2_.html
    Does this answer your question?
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    (Original post by CCJ)
    I'm having trouble getting my head around this, it doesn't really make any sense.

    I understand the Na-K pump, and its role in the resting potential. I get the Action potential, how the stimulus changes permeability of the axon membrane to Na+ ions, thus increasing the PD from -65 mV to +40 mV, and how when the channel closes and K+ ions flood out to stabilise the electrochemical balance to reach the original resting potential.

    But what I don't understand is how this whole sequence of action potential, can be transmitted across a neurone because the movement of ions is happening perpendicular to the supposed direction.

    This is what I think happens but I'm not 100% sure and if anyone could correct me, please do and explain.

    So the influx of Na+ ions inside the axon from the action potential, moves across the axon to a more negative potential area. This depolarises the surrounding negative area to positive due to the surge of Na+ down an electrochemical gradient. This then skips the stage of the action potential mechanism, where the permeability of Na+ ions is made available to diffuse them inside the axon, and goes straight into the stage where the K+ channels open to stabilise the electrochemical balance. So the same Na+ ions that flooded in from the first action potential move across the whole axon to the end.

    Any help, much appreciated.
    Depolarisation of an area allows the adjacent portion of the neurone to be depolarised by the creation of local circuits, hence resulting in the propagation of the action potential and the opening of Na+ gated channels in that region

    Hope it helps!
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    Also look up saltatory action
 
 
 
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