PSIO 303A Lecture Notes - Lecture 25: Transcellular Transport, Proximal Tubule, Tight Junction
26 Oct 2016
School
Department
Course
Document Summary
Block 2 - lecture 10 - integration of transport concepts. Epithelia as a case study in the integration of transport concepts. Exposed to interstitial fluid that is continuous with the blood. Epithelial cells are connected via tight junctions, these tight junctions: Prevent mixing of integral proteins in the distinct basolateral and apical domains. Transepithelial movement of solutes/water between epithelial cells (selectivity characteristics have to do with claudins protein within the tight junctions) Movement of solutes/water across the distinct basolateral and apical domain. Carriers and channels are involved in this transport. Absorption: transepithelial flux that goes from apical to basolateral. Secretion: transepithelial flux that goes from basolateral to apical. Transepithelial transport - na,glucose-absorption (small intestine and renal proximal tubule) Any solute undergoing a net active transepithelial flux must use the transcellular pathway because the cell membrane is the only site where metabolic energy can be linked to transport events.
