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Sea_Guide7219 OP t1_jeeyf7z wrote

Reply to comment by CrateDane in Is osmotic pressure involved in the circulation of ions through a cell membrane ? by Sea_Guide7219

Thank you.

I still really suspect that the idea of an "osmotic force" causing ions to follow their concentration gradient is not rigorous.

I've found a textbook (fundamentals of biochemistry) which gives two definitions :

  1. osmosis is the net movement of solvent across a semipermeable membrane from a region of high concentration, to a region of low concentration.

  2. osmotic pressure is the pressure one have to apply to equalize the flow of the solvent through the membrane in both direction.

So, it seems to me, again, that it's not rigorous to say that the movement of ions following their concentration gradient is due to "a force", and that this force may be called "osmotic force". Indeed, as far as I know the only thing we define as an "osmotic force" is "osmotic pressure", and it's the pressure needed to "cancel osmosis" if I may say so. So it's exactly the opposit of ion's following their concentration gradient.

I don't know if I that makes sense...

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