PHGY 210 Lecture Notes - Lecture 33: Proximal Tubule, Extracellular Fluid, Tubular Fluid
Mar 29, 2017
Glomerular Filtration
What is filtered by glomerular filtration?
-calcium binds strongly to albumin hence they don’t pass through as much
-fatty acids are very sticky and stick to albumin and don’t pass through
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Glomerular Filtration Rate
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Regulation of GFR
Filtered Load
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Document Summary
Calcium binds strongly to albumin hence they don"t pass through as much. Fatty acids are very sticky and stick to albumin and don"t pass through. Two mechanisms of reabsorption: diffusion and mediated transport. Reabsorption by diffusion: often across tight junctions connecting tubular epithelial cells. Urea diffuses into interstitial fluid and peritubular capillaries. Reabsorption by mediated transport occurs across tubular cells (transcellular epithelial transport) Requires participation of transport proteins in plasma membrane of tubular cells. Mechanisms of solute transport (different way to classify) When membrane transport proteins become saturated, tubule cannot reabsorb substance any more. E. g. in people w/ uncontrolled diabetes mellitus, plasma concentration of glucose can become very high and filtered load of glucose exceeds capacity of tubules to reabsorb glucose (tm is exceeded) Tubular secretion moves substances from peritubular capillaries into tubular lumen (opposite of reabsorption) Most important substances secreted by tubules: hydrogen ion and potassium. Tubular secretion is usually coupled to reabsorption of sodium.