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    Erm can anybody explain oncotic pressure as well as hydrostatic pressure an what ever happens at the arteriole and venuous ends of the capillaries. Will beusing this thread till late for any queries.
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    From inside the capillaries, think of hydrostatic pressure as the 'pushing force', pushing the fluid out of the capillaries. It's the result of the actual pressure of the fluid on the capillary walls.*

    Oncotic pressure, is the 'pulling force', pulling fluids from the surrounding tissue into the capillaries.

    As fluid leaves the capillaries as a result of hydrostatic pressure, large proteins cannot pass through the capillary walls. This results in a greater concentration of solutes inside the capillaries as opposed to outside of them, and the oncotic pressure rises, pulling more water into the capillaries in order to balance the solute concentration.

    Whenever hydrostatic pressure is greater than oncotic pressure, fluid will leave the capillaries, whenever the onctoic pressure is greater than the hydrostatic pressure fluid will enter the capillaries.

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    So when the blood leaves the arteries, it goes through the artrioles (this is obviously the arteriole end of the capillary due to the high pressure, the blood is forced out of the capillaries as tissue fluid. This is the hydrostatic pressure.

    To go back into the capillaries, I am not 100% sure about this but the venule end of the capillary has a much lower hydrostatic pressure than the arteriole end. Due to the blood and tissue fluid having more solutes in them they have a lower water potential than in the capillaries (theyve also lost alot of water) so they go down the water potential gradient back into the capillaries. This is the oncotic pressure.

    Like I said Im not sure if its 100% true, pls correct me if it isnt.
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    (Original post by talsxo)
    So when the blood leaves the arteries, it goes through the artrioles (this is obviously the arteriole end of the capillary due to the high pressure, the blood is forced out of the capillaries as tissue fluid. This is the hydrostatic pressure.

    To go back into the capillaries, I am not 100% sure about this but the venule end of the capillary has a much lower hydrostatic pressure than the arteriole end. Due to the blood and tissue fluid having more solutes in them they have a lower water potential than in the capillaries (theyve also lost alot of water) so they go down the water potential gradient back into the capillaries. This is the oncotic pressure.

    Like I said Im not sure if its 100% true, pls correct me if it isnt.
    Yup that's pretty much it!! Try and understand it maybe by looking at a diagram and repeat it to yourself. I'm doing the exam tomorrow eurghhhh then chem on Friday.

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    (Original post by mali473)
    Yup that's pretty much right!! Try and understand it maybe by looking at a diagram nd repeat it to yourself. I'm doing the exam tomorrow eurghhhh then chem on Friday.

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    it took me so long to understand, Im still revising it all now, especially the transport in plants topic and same! I think both are gonna be hard
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    (Original post by talsxo)
    it took me so long to understand, Im still revising it all now, especially the transport in plants topic and same! I think both are gonna be hard
    I haven't revised chem yet at all for the past month I'm doomed. I've gone over everthing briefly tomorrow morning I'm going to go over the heart topic again and attempt a few questions

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    [QUOTE=mali473;65182883]From inside the capillaries, think of hydrostatic pressure as the 'pushing force', pushing the fluid out of the capillaries. It's the result of the actual pressure of the fluid on the capillary walls.*

    Oncotic pressure, is the 'pulling force', pulling fluids from the surrounding tissue into the capillaries.

    As fluid leaves the capillaries as a result of hydrostatic pressure, large proteins cannot pass through the capillary walls. This results in a greater concentration of solutes inside the capillaries as opposed to outside of them, and the oncotic pressure rises, pulling more water into the capillaries in order to balance the solute concentration.

    Whenever hydrostatic pressure is greater than oncotic pressure, fluid will leave the capillaries, whenever the onctoic pressure is greater than the hydrostatic pressure fluid will enter the capillaries.

    Posted from TSR Mobile[/QUOT
    So at th e arteriole end let me think. sincr solute senter the capillaries solute potenial is higher outside the capillary which meqnswater potential is lowet outside thr capillaries so water moves out of the capillsry. According to ehat you said i assume that there would be a higher hydrostatic pressure than oncotic pressure in the capillaries at this end. Excuse thr typos im in the dark on a dodgy tablet lol
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    Next...what cofactors do we need to know??
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    (Original post by mali473)
    I haven't revised chem yet at all for the past month I'm doomed. I've gone over everthing briefly tomorrow morning I'm going to go over the heart topic again and attempt a few questions

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    past month! procrastination hit you hard & yeah sounds like a good idea
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    (Original post by sia_x11)
    Next...what cofactors do we need to know??

    I revise using the spec & all it says is know 'Cl- (the ion) as a cofactor for amylase, Zn2+ (ion) as a prosthetic group for carbonic anhydrase and that we get coenzymes from vitamins
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    So at th e arteriole end let me think. sincr solute senter the capillaries solute potenial is higher outside the capillary which meqnswater potential is lowet outside thr capillaries so water moves out of the capillsry. According to ehat you said i assume that there would be a higher hydrostatic pressure than oncotic pressure in the capillaries at this end. Excuse thr typos im in the dark on a dodgy tablet lol[/QUOTE]


    Tissue fluid is formed because of the high hydrostatic pressure of the blood at the arteriole end of the capillary that pushes fluid out of the blood.

    The blood contains plasma proteins giving the blood a relatively high solute potential (and therefore a low water potential), tending to draw water into the blood. Since the hydrostatic pressure has a greater effect than the solute potential at the arteriole end, the net effect is that fluid leaves the capillary. No blood cells or large proteins leave as they are too big to fit through the gaps.

    At the venule end of the capillary, since fluid has been lost, the hydrostatic pressure of the blood is lower and the solute potential is higher. Because of this, fluid drains back into the blood. At this stage, the useful materials such as amino acids and glucose will have been taken up by the cells and the tissue fluid will now contain waste substances such as carbon dioxide and urea.

    Get it?

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    (Original post by talsxo)
    past month! procrastination hit you hard & yeah sounds like a good idea
    Tell me about it. I'm so stressed and its my fault :/

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    [QUOTE=talsxo;65182949]So when the blood leaves the arteries, it goes through the artrioles (this is obviously the arteriole end of the capillary due to the high pressure, the blood is forced out of the capillaries as tissue fluid. This is the hydrostatic pressure.

    To go back into the capillaries, I am not 100% sure about this but the venule end of the capillary has a much lower hydrostatic pressure than the arteriole end. Due to the blood and tissue fluid having more solutes in them they have a lower water potential than in the capillaries (theyve also lost alot of water) so they go down the water potential gradient back into the capillaries. This is the oncotic pressure

    The venule end does have a loweer hydrostatic pressure and higher oncotic pressure so water moves in. Careful oncotic pressure and water pontential are not the same thing. Water moves down the water potential gradient from outside the capillary to inside at the venule end. Thinking about it they have similar effects but i dont want to confuse the,m
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    (Original post by mali473)
    So at th e arteriole end let me think. sincr solute senter the capillaries solute potenial is higher outside the capillary which meqnswater potential is lowet outside thr capillaries so water moves out of the capillsry. According to ehat you said i assume that there would be a higher hydrostatic pressure than oncotic pressure in the capillaries at this end. Excuse thr typos im in the dark on a dodgy tablet lol

    Tissue fluid is formed because of the high hydrostatic pressure of the blood at the arteriole end of the capillary that pushes fluid out of the blood.

    The blood contains plasma proteins giving the blood a relatively high solute potential (and therefore a low water potential), tending to draw water into the blood. Since the hydrostatic pressure has a greater effect than the solute potential at the arteriole end, the net effect is that fluid leaves the capillary. No blood cells or large proteins leave as they are too big to fit through the gaps.

    At the venule end of the capillary, since fluid has been lost, the hydrostatic pressure of the blood is lower and the solute potential is higher. Because of this, fluid drains back into the blood. At this stage, the useful materials such as amino acids and glucose will have been taken up by the cells and the tissue fluid will now contain waste substances such as carbon dioxide and urea.

    Get it?

    Posted from TSR Mobile[/QUOTE]

    Okay yeah i get the formation of tissue fluid becaise of the the higher hydrostatic pressure but does water basically move out then
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    Thank you thank you
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    (Original post by sia_x11)
    Tissue fluid is formed because of the high hydrostatic pressure of the blood at the arteriole end of the capillary that pushes fluid out of the blood.

    The blood contains plasma proteins giving the blood a relatively high solute potential (and therefore a low water potential), tending to draw water into the blood. Since the hydrostatic pressure has a greater effect than the solute potential at the arteriole end, the net effect is that fluid leaves the capillary. No blood cells or large proteins leave as they are too big to fit through the gaps.

    At the venule end of the capillary, since fluid has been lost, the hydrostatic pressure of the blood is lower and the solute potential is higher. Because of this, fluid drains back into the blood. At this stage, the useful materials such as amino acids and glucose will have been taken up by the cells and the tissue fluid will now contain waste substances such as carbon dioxide and urea.

    Get it?

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    Okay yeah i get the formation of tissue fluid becaise of the the higher hydrostatic pressure but does water basically move out then[/QUOTE]

    There's not much water in the blood stream.

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    (Original post by talsxo)
    I revise using the spec & all it says is know 'Cl- (the ion) as a cofactor for amylase, Zn2+ (ion) as a prosthetic group for carbonic anhydrase and that we get coenzymes from vitamins
    Me too just wanted to double check
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    Following this how da **** am i supposed to remember all the norganic ion functions. Does anyone have a brainstorm or something visual..?
 
 
 
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