PART 2 The Urinary System

Uriniferous Tubule Figure 23.5a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

The Nephron Renal corpuscle Glomerulus and glomerular capsule Glomerulus – tuft of capillaries Capillaries of glomerulus are fenestrated Glomerular (Bowman’s) capsule Parietal layer – simple squamous epithelium Visceral layer – consists of podocytes Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Renal Corpuscle and the Filtration Membrane Figure 23.6a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Renal Corpuscle and the Filtration Membrane Figure 23.6c Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Tubular Section of Nephron Filtrate proceeds to renal tubules from glomerulus Proximal convoluted tubule Loop of Henle Descending limb Thin segment Thick segment Distal convoluted tubule Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Micrograph through the Renal Medulla Figure 23.7 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Juxtamedullary nephrons Classes of Nephron Cortical nephrons 85% of nephrons Juxtamedullary nephrons 15% of nephrons Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Collecting Tubules (Collecting ducts) Receive urine from distal convoluted tubules Figure 23.8 Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Classes of Nephron Figure 23.9a Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Microscopic Blood Vessels Nephrons associated with two types of capillary beds (a portal system) Glomerulus Fed and drained by arterioles Afferent and efferent arterioles Peritubular capillaries Arise from efferent arterioles Low-pressure, porous capillaries Absorb solutes Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

Microscopic Blood Vessels Vasa recta Thin-walled looping vessels Part of the kidney’s urine-concentrating mechanism Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings