Biological membranes unstirred water layer

When the intrinsic PAMPA data (P0) are corrected for the appropriate unstirred water layer permeability (P "), the unified relationship between the biological barrier data (Papp) and the artificial membrane data is ... 

Micellar solubilization of lipids within the intestinal lumen permits the lipids to diffuse to the surface of the intestinal epithelium and make contact with the microvillus membrane. This is important because there is a major physiological diffusion barrier called the unstirred water layer, that covers the surface of the epithelial cell membranes. The unstirred layer of water is a feature common to all biological membranes. Micelles penetrate this relatively immobile aqueous layer more readily, thus increasing the efficiency of lipid uptake into the intestinal mucosal cell. 

Transepithelialpotential the voltage measured across an epithelium. Unstirred layer, a relatively nonmobile layer of water and/or mucus secretions adjacent to a biological membrane. 

A layer of relatively unstirred water lies adjacent to all biological membranes. The boundary between the bulk water and this unstirred layer is indistinct but, nevertheless, it has a real thickness. During absorption, dmg molecules must diffuse across this layer and then... 

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