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    So I thought that for the resting potential to be restored-

    By active transport, sodium is pumped out of the neurone and potassium is pumped in.

    BUT now after doing some practice papers I see I am wrong!
    One mark scheme and the book basically says :

    -concentration gradient established by sodium potassium pump
    - there is no difference in charge between the inside and outside so potassium diffuses OUT of the neurone down the potassium gradient.

    YET

    another mark scheme says idea that the membrane remains permeable to potassium ions;
    -potassium ions {move because of charge difference / eq};
    - ions move INTO {nerve cell / neurone / axon / eq};
    -idea that potassium ion is removing a positive charge (from the outside)
    -idea that equilibrium is established e.g. diffusion gradient
    balanced by potential difference;


    SO- one is saying move in and one is saying out? Please could someone clarify! Its probably very easy im just in revision over load!

    Thanks!
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    (Original post by ELB141)
    So I thought that for the resting potential to be restored-

    By active transport, sodium is pumped out of the neurone and potassium is pumped in.

    BUT now after doing some practice papers I see I am wrong!
    One mark scheme and the book basically says :

    -concentration gradient established by sodium potassium pump
    - there is no difference in charge between the inside and outside so potassium diffuses OUT of the neurone down the potassium gradient.

    YET

    another mark scheme says idea that the membrane remains permeable to potassium ions;
    -potassium ions {move because of charge difference / eq};
    - ions move INTO {nerve cell / neurone / axon / eq};
    -idea that potassium ion is removing a positive charge (from the outside)
    -idea that equilibrium is established e.g. diffusion gradient
    balanced by potential difference;


    SO- one is saying move in and one is saying out? Please could someone clarify! Its probably very easy im just in revision over load!

    Thanks!
    Urm..I think this is right (can't check atm) but:

    After depolarisation/action potential, a crazy amount if sodium enters the neurone.
    To restore the membrane potential, potassium channels open allowing potassium to exit the cell.
    Eventually, potassium channels close but too much leaves the neurone (hyperpolarisation)
    This is restored by the Na-K pump which REMOVES Na and BRINGS IN K.

    I apologise if this is incorrect, but as far as my brain is working atm, it should be right.

    Hope this helped.


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    (Original post by ash92:))
    Urm..I think this is right (can't check atm) but:

    After depolarisation/action potential, a crazy amount if sodium enters the neurone.
    To restore the membrane potential, potassium channels open allowing potassium to exit the cell.
    Eventually, potassium channels close but too much leaves the neurone (hyperpolarisation)
    This is restored by the Na-K pump which REMOVES Na and BRINGS IN K.

    I apologise if this is incorrect, but as far as my brain is working atm, it should be right.

    Hope this helped.




    This was posted from The Student Room's iPhone/iPad App
    Thank you! That's what I have written on my revision cards too... Just confused myself I think!
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    (Original post by ELB141)
    Thank you! That's what I have written on my revision cards too... Just confused myself I think!
    You're welcome

    And it is confusing at first, you are not alone


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