Normally when oncotic pressure is measured it is

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Unformatted text preview: se in protein concentration. Normally, when oncotic pressure is measured, it is measured across a semipermeable membrane i.e., a membrane that is permeable to fluid and electrolytes but not to large protein molecules. In most capillaries, however, the wall (primarily endothelium) does have a finite permeability to proteins. The actual permeability to protein depends upon the type of capillary as well as the nature of the protein (size, shape, charge). Because 6 Pulmonary Circulation of this finite permeability, the actual oncotic pressure generated across the capillary membrane is less than that calculated from the protein concentration. The effects of finite protein permeability on the physiological oncotic pressure can be determined knowing the reflection coefficient (s ) of the capillary wall. If the capillary is impermeable to protein then s = 1. If the capillary is freely permeable to protein, then s = 0. Continuous capillaries have a high s (>0.9), whereas discontinuous capillaries which are very "leaky&qu...
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This note was uploaded on 04/18/2008 for the course PHYS 1010 taught by Professor Thompson during the Fall '07 term at New York Medical College.

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