Renal Tubular Transport Medical Notes PDF
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Terdthai Tong-un, MD
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Summary
These notes comprehensively cover renal tubular transport, offering detailed information on various aspects of kidney function, including mechanisms of reabsorption and secretion of different substances.
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The Urinary System Tubular transport Terdthai Tong-un, MD Department of Physiology Contents and Objectives Renal tubular transport of each part Substance handling by renal tubule Mechanism of tubular transport...
The Urinary System Tubular transport Terdthai Tong-un, MD Department of Physiology Contents and Objectives Renal tubular transport of each part Substance handling by renal tubule Mechanism of tubular transport Guyton.,2011 PCT transport Reabsorption =>60-80% , 2/3 volume DHL transport Para cellular => Mg, Ca Reabsorption =>H2O 15% (AQP1 both apical basolateral and vasa recta) AHL transport Reabsorption =>NaCl 25% No reabsorption=> H2O Loop diuretic block NKCC Early DCT transport Reabsorption =>NaCl 10% (luminal) Late DCT & CD transport Water reabsorption affect by ADH Na reabsorption affect by aldosterone Inner Medullary CD transport Water, Urea reabsorption affect by ADH Na reabsorption affect by aldosterone Substance Handling by PCT Guyton.,2011 Substance Handling by Renal Tubule Guyton.,2011 Substance & Fractional Excretion (FE) Substance Measure Filtered Reabsorbed Excreted FE H2 0 L/day 180 178 1.5 0.008 Na+ meq/day 25,200 25,050 150 0.006 K+ meq/day 720 620 100 0.14 Ca2+ meq/day 540 530 10 0.02 HCO3- meq/day 4,320 4,318 2 0.0005 Cl- meq/day 18,000 17,850 150 0.008 Glucose mmol/day 800 800 0 0 Urea gm/day 56 28 28 0.5 * FE=Fractional Excretion Bruce MK.,2008 FF & FE Filtration Fraction (FF) FFH2O = GFR/RPF Fractional Excretion (FE) Type FE (%) FEX = ExcretedX / FiltratedX Pre 2 – ExcretedNa = UNa x V Post >4 – FiltratedNa = PNa x GFR – GFR = UCr x V / PCr FENa = UNa x PCr PNa x UCr Determines if renal failure is due to pre-renal, intrinsic, or post-renal pathology. Do not use in patients taking diuretics or with known chronic kidney disease, urinary tract obstruction, or acute glomerular disease Na-AHL transport and Loop diuretics ROMK Guyton.,2011 Na-Early DCT transport and diuretics Ca Na NCC Guyton.,2011 Na-Late DCT & CD transport - diuretics Water reabsorption affect by ADH Na reabsorption affect by aldosterone ROMK, BK (Big K) ENaC Guyton.,2011 H secretion-PCT,CD NHE,H-ATPase NBC1 (Na-HCO3) HK,H-ATPase AE1 (Cl-HCO3) https://journals.physiology.org/doi/full/10.1152/physrev.00045.2003 H secretion- CD www.ncbi.nlm.nih.gov/pmc/articles/PMC2806118 Glucose reabsorption Urea reabsorption & secretion Proximal convoluted tubule reabsorption Collecting duct Dilute urine passes out UNLESS ADH inserts aquaporin Then water leaves and urine concentrates Descending limb Freely permeable to water Water lost by osmosis Distal tubule Selective secretion and absorption Ascending limb Impermeable to water Permeable to ions- diffuse out
