when does osmosis stop

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leeroykincaid
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when does osmosis stop

Post by leeroykincaid » Mon Feb 12, 2018 6:56 am

I have a question about osmosis that goes a bit deeper than most basic textbooks so I cannot find the answer.Here's the problem:

Imagine an animal cell, say a red blood cell, in a slightly hypotonic solution. The water starts to flow in osmotically. The concentration of solute in the cell decreases. The cell slowly starts to swell but does not burst.

The question is: Does this water entering increases the pressure on the membrane (similar to turgor in plant cells only less, because the cell can increase in volume - comparable to elastic energy that must be overcome when blowing a baloon...) and does this cause osmosis to stop BEFORE the concentrations come to equilibrum (meaning that cytoplasm still has a bit more solute concentration than outside of cell) or do the concentrations perfectly match?

Thanx in advance.

claudepa
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Re: when does osmosis stop

Post by claudepa » Mon Feb 12, 2018 9:55 am

Obviously you already know more on osmosis than me. In my mind osmosis stops when concentrations are similar Inside and outside the cell. If this wrong I am ready to change my view of osmosis.

leeroykincaid
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Re: when does osmosis stop

Post by leeroykincaid » Tue Feb 13, 2018 6:34 pm

I found this, which I think proves my point, but I cannot say i really understand all the math behind it.

https://imgur.com/a/gasXl

http://www.princeton.edu/~akosmrlj/MAE5 ... slides.pdf

claudepa
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Re: when does osmosis stop

Post by claudepa » Tue Feb 13, 2018 8:09 pm

it seems that the Princeton file also describes equal concentrations Inside and outside

leeroykincaid
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Re: when does osmosis stop

Post by leeroykincaid » Tue Feb 13, 2018 8:12 pm

Only when water comes out and the cell shrinks... Not when water comes in and the cell starts to swell - then the membrane tension comes into play.

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