WWEKANE
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I like to imagine cells as being on a paper. The tissue fluid surrounding cells will leave capillaries and go into a tissue(I think) this is similar to insects which have a haemocoel which has cells and blood comes into contact with cells.

My confusion lies as to why gravity doesn't pull blood down in tissues. Why doesn't the blood in tissues just all end up at the bottom due to gravity and not surrounding the cells instead.
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ThunderBeard
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Due to the pressure of the oxygenated blood going through the arteries forces it to go upwards. This is forcefulness is why arteries have thick elastic fibres and strong walls. However in veins there are valves to present the back flow of blood.
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WWEKANE
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So the arteries forces force tissue fluid upwards into tissues to become in contact with cells when the blood leaves the vessels? Thanks for the reply
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ThunderBeard
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(Original post by WWEKANE)
So the arteries forces force tissue fluid upwards into tissues to become in contact with cells when the blood leaves the vessels? Thanks for the reply
Tissue fluid? No, the blood passes near the cells where they diffuse into the required cells. Many cells make a tissue.
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WWEKANE
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But for insects they have a haemocoel. The blood just surrounds the cells. Why doesn't the blood just collapse to the bottom of the insect as they have no vessels in the haemocoel only haemolymph


Thanks.
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ThunderBeard
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(Original post by WWEKANE)
But for insects they have a haemocoel. The blood just surrounds the cells. Why doesn't the blood just collapse to the bottom of the insect as they have no vessels in the haemocoel only haemolymph


Thanks.
I’m sorry, I’m afraid I don’t know
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WWEKANE
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No problem. Thanks for your help
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sotor
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(Original post by ThunderBeard)
Tissue fluid? No, the blood passes near the cells where they diffuse into the required cells. Many cells make a tissue.
hey, not sure of what level of biology you're at but tissue fluid is a very important part of the circulation of animals, not mentioned until a level
essentially, blood plasma containing O2 and dissolved sugars and white blood cells is squeezed out of capillaries near tissues. this is how the substances carried in the liquid part of blood are actually able to diffuse into the cells, and CO2 out of the cells and into the blood. the capillary wall and cell membrane would otherwise make it difficult for the substances to get into cells. at the other end of the capillary, the fluid is squeezed back into the capillary.
(Original post by WWEKANE)
So the arteries forces force tissue fluid upwards into tissues to become in contact with cells when the blood leaves the vessels? Thanks for the reply
i've never learnt this as fact, but i believe it would be all to do with pressure and a kind of concentration gradient. so the tissue fluid is squeezed out of capillaries due to the hydrostatic pressure. flows over tissues etc, then reenters the capillary further along where the hydrostatic pressure is lower. as the fluid reenters the capillary, it will drag other water molecules with it (due to adsorption and cohesion, like a xylem vessel and transpiration) and pull the column of tissue fluid across the tissue. because the spaces are fairly small, the adsorption and cohesion of water would overcome the force of gravity (known as capillary action https://www.youtube.com/watch?v=YoF7...youtu.be&t=150).

i dont know of any biologists on here, but maybe someone knows better than me that's just what makes sense based on my a level standard knowledge haha
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ThunderBeard
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(Original post by sotor)
hey, not sure of what level of biology you're at but tissue fluid is a very important part of the circulation of animals, not mentioned until a level
essentially, blood plasma containing O2 and dissolved sugars and white blood cells is squeezed out of capillaries near tissues. this is how the substances carried in the liquid part of blood are actually able to diffuse into the cells, and CO2 out of the cells and into the blood. the capillary wall and cell membrane would otherwise make it difficult for the substances to get into cells. at the other end of the capillary, the fluid is squeezed back into the capillary.

i've never learnt this as fact, but i believe it would be all to do with pressure and a kind of concentration gradient. so the tissue fluid is squeezed out of capillaries due to the hydrostatic pressure. flows over tissues etc, then reenters the capillary further along where the hydrostatic pressure is lower. as the fluid reenters the capillary, it will drag other water molecules with it (due to adsorption and cohesion, like a xylem vessel and transpiration) and pull the column of tissue fluid across the tissue. because the spaces are fairly small, the adsorption and cohesion of water would overcome the force of gravity (known as capillary action https://www.youtube.com/watch?v=YoF7...youtu.be&t=150).

i dont know of any biologists on here, but maybe someone knows better than me that's just what makes sense based on my a level standard knowledge haha
Sorry, only up to gcse. Way outta my depth.
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sotor
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(Original post by ThunderBeard)
Sorry, only up to gcse. Way outta my depth.
haha dont even apologise just thought id explain in case you were curious what OP is talking about
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ThunderBeard
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Yep, taking bio next year. Thanks!
(Original post by sotor)
haha dont even apologise just thought id explain in case you were curious what OP is talking about
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