Why couldn't we get oxygen and nutrients into our body's cells just by diffusion and osmosis?

Question

im having trouble with my science homework and would like to know what are diffusion and osmosis. i have a hunch but im not quite sure. can someone pleeeease tell me what this question means? "why couldnt we get oxygen and nutrients into our body's cekks just by diffusion and osmosis"?

Answer 1

Yes as has bin said our body is too complicated to allow nutrients to be taken directly by diffusion or osmosis.We need a circulatory system to transport the nutrients to each cell of our body.Again being multicellular each tissue does not all but specialised roles.Thus even if nutients cud hv bin taken up directly,the cells won't b able 2 carry out the basic digestion done by our digestive system(a job that a unicellular organism can do on its own).Again a cell dat desperately needs a certain nutrient at a tym may not need it the nxt moment.Thus the membranes of cells need to be selectively permeable allowing the transport of some solutes while blocking dat of others at a given moment,Diffusion and osmosis r passive transports dat depend solely on concentration gradients and osmotic pressure respectively and do not confer such selective permeability.For eg a cell may need a nutrient dat is at a low concentration outside the cell.Thus diffusion obeying the concentration gradient wud take more of dat nutrient out of the cell.Thus the cell needs the help of energy coupled transport proteins dat carry it against the conc. gradient.But there r many examples of transport of nutrients which take place by diffusion(obviously wen the conc. gradient is in favour of the need of the cell).Its just dat diffusion wenever it occurs,it is frm the blood into the cell and not frm the external environment into the cell.

Answer 2

They are somewhat related. Diffusion deals with mass transfer in response to a concentration differences. So does diffusion, but it deals with one-way mass transfer. Actually, we do have this happen, but the body is too complicated to let each cell do this on its own from raw materials , so we have a body that serves up oxygen and nutrients via the circulatory and digestive systems.

Answer 3

The problem is that we have too much volume vs surface area. It takes too long for oxygen to diffuse into our bodies. This works for animals with very few cells because they have a lot of surface area vs volume. I hope that helps.

Answer 4

cos we are hererotrops and food cant just go into our bodies just like that
diffusion ------- movement of gases from surface into the cells this cant happen in our case cos allll cells [ deeply seeted once also need oxygen so blood is goind that work
osmosis ------- movement of solvent particles according to the concentration gradient