physiology text book

Discussion in 'Chemistry' started by Michael, Jul 31, 2009.

  1. Michael 歌舞伎 Valued Senior Member

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    I was reading a bit of neruo text in a book and it said: The reason why there is a gradient change on the inside and outside of the membrane is because the sodium ions have a stronger positive charge when compared with potassium ions.

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    THAT is not true. Right? I mean, wtf?!
     
    Last edited: Aug 1, 2009
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  3. Enmos Valued Senior Member

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    They probably mean that there are far more Sodium ions then Potassium ions on the outside of the membrane.

    The insides of cells contain large molecules that are negatively charged and can't cross the membrane.
    Ionpumps actively pump out Sodium ions to the outside. So there are more Sodium ions going out then there are Potassium ions coming in.
    There are more Sodium ions on the outside and more Potassium ions on the inside, and the inside has a net negative charge.
    This creates the gradient.

    Edit: Shouldn't this be in Biology ?

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    Last edited: Aug 1, 2009
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  5. S.A.M. uniquely dreadful Valued Senior Member

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    I think Enmos has nailed it. What the function of the Na-K-ATPase? To maintain the resting potential across the membrane. It pumps out 3 Na for every 2 K that enters into the cell.
     
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  7. Nasor Valued Senior Member

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    Well, sodium does have a higher charge density than potassium, since they both have the same charge but sodium is smaller. Sounds like you already figured it out though.
     
  8. Trippy ALEA IACTA EST Staff Member

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    Beat me to it again.

    Although let's not forget about effective nuclear charge.
    It's a small effect, but it's still present, and still has a measurable impact.
     

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