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Oncotic pressure
In blood plasma, the dissolved compounds have an osmotic pressure. A small portion of the total osmotic pressure is due to the presence of large protein molecules; this is known as the colloidal osmotic pressure, or oncotic pressure. Because large plasma proteins can't easily cross through the capillary walls, their effect on the osmotic pressure of the capillary interiors will, to some extent, balance out the tendency for fluid to leak out of the capillaries. In conditions where plasma proteins are reduced, e.g. from being lost in the urine (proteinuria) or from malnutrition, the result of the too low oncotic pressure can be edema - excess fluid buildup in the tissues.
Related to hydrostatic pressure.
10-26-2009 08:16:03
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The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details