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Why is sodium potassium pump required?

  1. Oct 8, 2009 #1
    Ok I searched and found this as the answer from a previous topic

    "The sodium potassium pump is required to maintain osmotic balance and stabilize the cells volume. If you treat an animal cell with ouabain, which inhibits the Na+/K+ pump, it will swell and often burst.

    Cells contain mostly negatively charged organic molecules, so they require cations for a counter charge balance: K+. This will create a large osmotic gradients, that would pull water into the cell, so it will pump out Na+.

    The pump is also able to generate membrane potential in nerve cells because of its electrogenic effect, but 90% of the membrane potential depends indirectly on the Na+/K+ pump."

    Questions I have

    1. Why do cells mostly contain negative charge. If this is due to proteins. What are the proteins inside cells.
    2. So my understanding is that K+ and Na+ try to neutralize the negative charge inside the cell. To reduce the solute concentration Na+ is sent out or else the cell would burst. I think this is wrong. Can someone please explain this to me.
    3. For nerve cells what membrane potential do they need. Do they want the inside of the cell to be negative.

    Thank you very much :smile:
     
  2. jcsd
  3. Oct 8, 2009 #2

    Andy Resnick

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    I disagree with the first sentence: "The sodium potassium pump is required to maintain osmotic balance and stabilize the cells volume. If you treat an animal cell with ouabain, which inhibits the Na+/K+ pump, it will swell and often burst."

    NaKATPase is the cell's battery- it charges up the membrane and maintains the membrane potential. IIRC, chloride transport is used to maintain cell volume, or alternatively, chloride channels are osmosensors.

    Cells are electrically neutral, like most matter. Proteins do indeed carry excess negative charge, but the majority of inorganic ions are positive- sodium and potassium. Cells have an excess of potassium inside, the intracellular milieu has an excess of sodium.
     
  4. Oct 8, 2009 #3

    Ygggdrasil

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    Nucleic acids (DNA & RNA) are another component of the cell that is highly negatively charged.
     
  5. Oct 9, 2009 #4
    sodium is poisonous to cells so they pump it out. then they pump potassium in to balance the change and osmotic pressure.

    even if the sodium/potassium pumps are inactive neurons can fire hundreds of thousands of times.
     
  6. Oct 12, 2009 #5
    hi !

    the NaK ATPase is required to maintain gradient of Na and K that are connected to function of plethor of transporter, in fact, many transporter use Na gradient as energy source (active secondary transport).

    The membrane potential is mostly due to K+ diffusion accross the membrane, so ATPase is important for maintain of this potential but not directly (except for few cell type).

    The effect that there are a membrane potential don't mean thaht the cell is charged, globally, the matter is electroneutral. The membrane potential is the consequence of a ion conductance difference (differential membrane permeability) and the phenomenon is so important as a very small charge asymmetry through the membrane is needed to make a diffusion potential.
     
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