15 - Renal Physiology - Lecture: Renal Physiology I....

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Lecture: Renal Physiology I. Overview of Nephron Structure and Function A. General Nephron Structure 1. glomerulus - site of filtration from arterial blood 2. proximal convolute tubule- first tube off glomer. 3. Loop of Henle - U-turn connecting tubules 4. distal convoluted tubule - to the Collecting Tubule 5. collecting tubule - urine from many nephron 6. peritubular capillaries - "around" the "tubes" B. General Nephron Function 1. glomerular filtration 2. tubular reabsorption 3. tubular secretion C. Fluid Processing in the Kidneys 180 liters of blood fluid processes each day 1.5 liters of urine produced each day II. Glomerular Filtration A. Filtration Membrane 1. hydrostatic pressure - forces 1/5 of blood fluid through capillary' walls into glomerular capsule 2. filtration membrane - has three parts a. fenestrated capillary endothelium (prevents passage of blood cells) b. basal membrane (allows most solutes but larger proteins) c. visceral membrane of glomerular capsule 3. solutes that can pass into glomerular capsule < 3 nm easily pass (water, sugar, amino acids, nitrogenous waste molecules) > 9 nm larger proteins cannot pass through B. Net Filtration Pressure NFP = force OUT of blood - force to remain IN blood NFP = glomerular - (glomerular + capsular ) hydrostatic osmotic hydrostatic pressure pressure pressure NFP = 55 mm Hg - ( 30 mm Hg + l5mmHg) NFP = 55 mm Hg - (45 mm Hg) NFP = net filtration pressure = 10 mm Hg [This is the NET forces pushing fluid/solutes OUT of blood] 1. glomerular filtration rate = milliliters of blood fluid filtered by glomerulus each minute Factors effecting the GFR:
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a. total filtration surface area b. membrane permeability to fluid/solutes c. Net Filtration Pressure 2. Normal GFR = 125 ml/min (7.5 L/hr, 180 L/day) 3. NFP - primary factor controlling GFR a. bleeding - NFP drops, lowers the pressure b. dehydration - NFP drops, lowers the pressure D. Intrinsic Controls: Regulation of Glomerular Filtration 1. renal autoregulation - rate of FILTRATE production must be coordinated with
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This note was uploaded on 10/19/2011 for the course PCB 3703C taught by Professor Asd during the Spring '09 term at University of Central Florida.

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15 - Renal Physiology - Lecture: Renal Physiology I....

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