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Old 05-01-2013
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Default Osmolarity concept please help.

In Kaplan I am told when RBC is placed in a solution of 500 mOsm urea only, the cell will swell. Why and how?
The explanation was that the effective osmolarity is zero. Why?
Pls help.
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Old 05-01-2013
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I was thinking that since urea is rapidly penetrating substance it would diffuse quickly to equiliberate the concentration in the icf and ecf space and so there shd be no change in osmolarity in both icf and ecf. But I was told the cell would swell.
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Old 05-01-2013
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Urea can freely move across the membrane and will equiliberate. Therefore the change in osmolarity due to urea will be the same inside and outside the cell.However the cell already has an osmolarity of 300 mOsm. So the cell will swell.
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