The Kidney and NephronChapter 20

Location

Kidney Structure

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

http://www.kumc.edu/instruction/medicine/pathology/ed/ch_16/c16_sglomerulus_nl.jpg

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