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    So we have a nice little neurone with some cell thingies in it...
    it's at -60mV okay that's nice and at it's resting potential...
    along comes some stimulus... woooo... some Na moves out...
    Now what I don't understand is why that makes it less negative? Surely, it would make it more negative. 3Na out... 2K in... surely that creates an ion debt? If someone can help me that'd be great.
    (My plus button is broken btw, I'm sorry)
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    Starting from resting potential, the p.d is at around -70 mV.

    So when there's a particular stimulus, The Na+ ion channels will open, resulting in the flooding of Na+ ions into the axon. ( the K+ ions channels are closed). This will cause the p.d of that point to increase up until approx. +40 mV. This is known as depolarisation.

    After reaching the peak, the Na+ ions channels will close and subsequently the K+ ions channels will reopen. This would result in an outward movement of K+ ions, causing the p.d to decrease. This is known as repolarisation. ( Sometimes the outward movement will exceed the p.d of resting potential, causing hyperpolarisation but eventually the p.d will return back to -40 mV). Afterwards, the K+ ions channels will close and the sodium-potassium pumps work again to reestablish and maintain the resting potential.
 
 
 
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