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    If the blood in the capillaries, which surround the alveoli, did not flow, how would this prevent a diffusion gradient from being maintained for gaseous exchange?
    In other words, wouldn't the CO2 still diffuse from the blood and then into alveolus?

    Alternatively, if the lungs was not ventilated, how would this prevent a diffusion gradient from being formed?
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    (Original post by zigocarn)
    If the blood in the capillaries, which surround the alveoli, did not flow, how would this prevent a diffusion gradient from being maintained for gaseous exchange?
    In other words, wouldn't the CO2 still diffuse from the blood and then into alveolus?

    Alternatively, if the lungs was not ventilated, how would this prevent a diffusion gradient from being formed?

    Think about it logically and slowly:

    If the blood isn't moving it will give all of it's CO2 up and take up all it's O2, so you're right, it would still diffuse initially. Except then it wouldn't move away. The body would continue producing CO2 and demanding O2 but the blood in the lungs with the o2 isn't getting anywhere and the blood collecting the CO2 would not make it to the lungs.

    The O2 and Co2 would normalise and then there will be no difference anymore to drive the diffusion.

    If you're not ventilating, then the amount of CO2 in the lungs would rise until there would be no difference in the levels in the lungs and the blood and CO2 wouldn't move. O2 would get used up and there would be no o2 left to diffuse in!
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    (Original post by Neostigmine)
    Think about it logically and slowly:

    If the blood isn't moving it will give all of it's CO2 up and take up all it's O2, so you're right, it would still diffuse initially. Except then it wouldn't move away. The body would continue producing CO2 and demanding O2 but the blood in the lungs with the o2 isn't getting anywhere and the blood collecting the CO2 would not make it to the lungs.

    The O2 and Co2 would normalise and then there will be no difference anymore to drive the diffusion.

    If you're not ventilating, then the amount of CO2 in the lungs would rise until there would be no difference in the levels in the lungs and the blood and CO2 wouldn't move. O2 would get used up and there would be no o2 left to diffuse in!
    Thank you for the response!

    Although, I'm not too sure what you mean by the O2 and CO2 'normalising'?
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    (Original post by zigocarn)
    Thank you for the response!

    Although, I'm not too sure what you mean by the O2 and CO2 'normalising'?
    I just mean it will equalise. It will diffuse until it is the same both sides.

    I didn't say equalise though as there are factors that stop it becoming perfectly equal, but that is really in depth and complicated science that isn't really relevant.
 
 
 
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