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    Hi,

    Can someone please explain why an action potential can only travel in one direction along the axon? I've tried looking online and in text books but I am still unsure!

    Thanks!
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    (Original post by DhylanP - CRGS)
    Hi,

    Can someone please explain why an action potential can only travel in one direction along the axon? I've tried looking online and in text books but I am still unsure!

    Thanks!
    Have you ever heard of the refractory period? When an action potential is generated, the sodium channels in the repolarising part of the axon close and inactive, thus no AP can form in that part of the axon for a short period of time. So the wave of depolarisation can only travel in one direction because it cannot travel back the way it just came. Also, the nervous system is organised in a way that allows signals to go in one direction, because the neurones are differentiated in such a way that means that neurotransmitters can only leave at the end of an axon and not anywhere else, so this means that neurone 1 can stimulate neurone 2, and neurone 2 then stimulates neurone 3, but neurone 2 cannot stimulate neurone 1. But the main point here is the refractory period. If you don't understand what that is then just let me know and I'll explain
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    1. Refractory period provides a time delay between one impulse and the next as ion channels are closed and recovering
    2. Specific receptors exist on post synaptic neurones so only these neurones can be depolarised to begin action potential
    3.neurotransmitters (e.g acetylcholine) are only released from the presynaptic neurone so action potentials can only be set up at the post synaptic neurone where neurotransmitters bind to receptors
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    (Original post by AortaStudyMore)
    Have you ever heard of the refractory period? When an action potential is generated, the sodium channels in the repolarising part of the axon close and inactive, thus no AP can form in that part of the axon for a short period of time. So the wave of depolarisation can only travel in one direction because it cannot travel back the way it just came. Also, the nervous system is organised in a way that allows signals to go in one direction, because the neurones are differentiated in such a way that means that neurotransmitters can only leave at the end of an axon and not anywhere else, so this means that neurone 1 can stimulate neurone 2, and neurone 2 then stimulates neurone 3, but neurone 2 cannot stimulate neurone 1. But the main point here is the refractory period. If you don't understand what that is then just let me know and I'll explain
    But isn't spatial summation of actional potentials when different ap from different neurones induce a single ap in another neurone?
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    Only the pre synaptic neurone can release a neurotransmitter therefore the action potential can only travel in one direction.
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    (Original post by LLearnt)
    But isn't spatial summation of actional potentials when different ap from different neurones induce a single ap in another neurone?
    yh, but I wasn't talking about that :P
 
 
 
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