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BIO: How does respiration contribute to the resting potential in neurones? watch

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    Hi, I am very stuck on this question, and I dont even reckon it makes any sense. Although, I am obviously missing something....

    The actual question is:
    Explain the roles of respiration in maintaining a resting potential across neurones


    Please help thanks
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    I suppose its not much but I'll have a stab at it:

    ATP is needed in order to actively pump out sodium ions out of the axon to the point where there are 3 sodium ions outside the axon for every two potassium ions inside. In this way a resting potential of -40mV is achieved across the membrane. The ATP to power this, is derived from respiration.
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    (Original post by ResidentEvil)
    Hi, I am very stuck on this question, and I dont even reckon it makes any sense. Although, I am obviously missing something....

    The actual question is:
    Explain the roles of respiration in maintaining a resting potential across neurones


    Please help thanks
    The resting potential is maintained by the effect of the sodium potassium pump, which acts actively. The energy for active transport is provided in the form of ATP, which is generated through respiration.
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    (Original post by cipapfatso)
    I suppose its not much but I'll have a stab at it:

    ATP is needed in order to actively pump out sodium ions out of the axon to the point where there are 3 sodium ions outside the axon for every two potassium ions inside. In this way a resting potential of -40mV is achieved across the membrane. The ATP to power this, is derived from respiration.
    Good, but not quite accurate - the Na/K ATPase pumps 3 Na out for every 2 K in, but they are not actually in that ratio across the membrane. Actual concentrations are something like K: 150mM inside, 4mM outside; Na: 5mM inside, 140-150mM outside. And RP can go down to at least -60mV
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    so to summarise: Respiration provides energy ATP to activate the sodium potassium pumps in neurones?

    What about the voltage-gated channels? are they too activated by ATP?
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    (Original post by ResidentEvil)
    What about the voltage-gated channels? are they too activated by ATP?
    No, they are activated by a stimulus (i think!)
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    (Original post by ResidentEvil)
    so to summarise: Respiration provides energy ATP to activate the sodium potassium pumps in neurones?

    What about the voltage-gated channels? are they too activated by ATP?
    No, they are voltage-gated. That means that the probability of their being open at any one time is a function of the voltage across the membrane. Nowt to do with ATP.
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    OMG i am so confused.

    Lemme traceback................

    Resting potential we have 3 sodiums pumping out and 2 potassium pumping in through K+ and Na+ channels using ATP, whilst potassium diffuses slower than sodium, causing a more negative charge inside the neurone.

    Next, when a stimulus arrives it initiates an electrical potential difference causing voltage-gated channels of Na to open depolarising the membrane etc....

    But how does the stimulus alter the voltage in the first place?????????
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    please visit http://www.uk-learning.net/t46063.html for more bio questions!
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    (Original post by ResidentEvil)
    OMG i am so confused.

    Lemme traceback................

    Resting potential we have 3 sodiums pumping out and 2 potassium pumping in through K+ and Na+ channels using ATP, whilst potassium diffuses slower than sodium, causing a more negative charge inside the neurone.

    Next, when a stimulus arrives it initiates an electrical potential difference causing voltage-gated channels of Na to open depolarising the membrane etc....

    But how does the stimulus alter the voltage in the first place?????????
    Ok...at resting potential, the membrane is slightly permeable to potassium and basically impermeable to sodium. Potassium ions would, therefore, move out of the cell, but this is (as far as you need to know, anyway) opposed by the pump, which maintains the voltage difference.

    Stimulating the nerve electrically results in a brief inward current of sodium ions, as the voltage gated channels open transiently. This alters the membrane potential (depolarisation) and as the depolarisation spreads outwards, it opens more Na channels, so the AP is propagated. It's complicated stuff, I'm afraid.
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    this is for A2 isn't it?
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    (Original post by Helenia)
    Ok...at resting potential, the membrane is slightly permeable to potassium and basically impermeable to sodium. Potassium ions would, therefore, move out of the cell, but this is (as far as you need to know, anyway) opposed by the pump, which maintains the voltage difference.

    Stimulating the nerve electrically results in a brief inward current of sodium ions, as the voltage gated channels open transiently. This alters the membrane potential (depolarisation) and as the depolarisation spreads outwards, it opens more Na channels, so the AP is propagated. It's complicated stuff, I'm afraid.
    yeah ok that makes more sense now, its just u were a bit vague and unclear previously.

    What biology board are u with?
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    (Original post by ResidentEvil)
    yeah ok that makes more sense now, its just u were a bit vague and unclear previously.

    What biology board are u with?
    Sorry, it's fluffy stuff as it is, hard to be precise without going into unnecessary detail. I did OCR, but I'm a first year medic now, so have done nerve conduction in more detail in Physiology lectures.
 
 
 

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