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The Kidney and Nephron Chapter 20
The Kidney and NephronChapter 20
Location
Kidney Function Regulate volume, composition, and pH of
body fluids Remove metabolic wastes from blood and
excrete (mainly N and S compounds from protein metabolism)
Control rate of rbc formation -erythropoietin
Regulate blood pressure - renin Absorbs Ca2+ and activates vitamin D
Dialysis
Peritoneal Dialysis
Hemodialysis
Blood Supply
Renal Artery & Vein = contain 15-30% of total cardiac output
Nephron
aka -Loop of Henle
aka –Bowman’s Capsule
Glomerulus
Glomerulus
Juxtaglomerular Apparatus
Renin secretion – regulates [Na+ ] and therefore, blood volume
Collecting Duct = simple cuboidal epithelium
Tubules D=distal P=proximal
Urine Formation
180 L of fluids are filtered every
24 hours!
Urine Formation Overview
Blood pressure causes filtration by size of molecule
Blood Filtration
WaterElectrolytesGlucoseUrea
Urine Composition
Urea By- product of aa catabolism Reflects amt. of protein in
diet Contributes to water
reabsorption
Uric Acid By- product of nucleic acid
catabolism (A & G) Filtered out in glomerulus Cause of Gout
Creatinine• Waste product of muscle action
90% is Water• Volume varies with fluid intake and
environment
Trace amounts of:• Amino acids, electrolyes, glucose
Gout
Gout
Urinary Excretion in Nephron
ADH – antidiuretic hormone
Regulates water volume - Makes DCT permeable to water for reabsorption
Secreted when dehydrated = more concentrated urine
Caffeine
AlcoholDecreases ADH, which decreases water reabsorption
Decreases Na+ absorption, which decreases amount of water you will hold.
Kidney Stones
