PowerPoint® Lecture Slides The Urinary System prepared by Leslie Hendon • Important functions of the kidneys University of Alabama, Birmingham • Maintain the chemical consistency of blood (water, electrolytes, acid/base balance) • Filter many liters of fluid from blood and send toxins, metabolic wastes, and excess water out of the body C H A P T E R 24 • Main waste products Part 1 • Urea • Uric acid The Urinary • Creatinine System • Contribute to blood pressure control (renin system) • Stimulate rbc production through erythropoietin Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Organs of the Urinary System Organs of the Urinary System Hepatic veins • Kidneys (cut) Esophagus (cut) Ureters Inferior vena • cava Renal artery Adrenal gland Renal hilum • Urinary bladder Aorta Renal vein Kidney • Urethra Iliac crest Ureter Rectum (cut) Uterus Urinary bladder Urethra (a) (b) Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Figure 24.1 Location and External Anatomy of Kidneys Relationship of the Kidneys to Vertebra and Ribs • Located retroperitoneally • Lateral to T12–L3 vertebrae • Average kidney is 12 cm tall, 6 cm wide, 3 cm thick • Hilum • On concave surface • Vessels and nerves enter and exit • Fibrous capsule surrounds the kidney • Perirenal fat—external to renal capsule • Renal fascia—external to perirenal fat 12th rib (b) Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Figure 24.2b 1 Position of the Kidneys with in the Posterior Internal Gross Anatomy of the Kidneys Abdominal Wall • Frontal section through the kidney shows: Renal cortex Anterior • Inferior vena cava • Renal medulla Aorta Peritoneal cavity Peritoneum (organs removed) Supportive • Renal pyramids Renal tissue layers vein Renal fascia • Renal columns anterior Renal posterior artery Perirenal • Renal pelvis, formed from convergence of… fat capsule Fibrous Body of capsule • Major calices (calyx = cup) vertebra L2 Body wall Minor calices (a) Posterior • Jejunum • Gross vasculature Duodenum • Renal arteries branch into segmental arteries Liver Inferior • Segmental arteries branch into interlobar arteries vena cava Left renal vein Aorta Left kidney • Arcuate arteries branch from interlobar arteries Right kidney Erector spinae muscle in posterior Vertebra L1 abdominal wall (c) Copyright © 2011 Pearson Education, Inc. Figure 24.2a, c Copyright © 2011 Pearson Education, Inc. Internal Gross Anatomy of the Kidneys Summary of Blood Vessels Supplying the Kidney Cortical radiate vein Renal hilum Cortical radiate artery Arcuate vein Renal cortex Arcuate artery Interlobar vein Renal Interlobar artery medulla Segmental arteries Renal vein Major calyx Renal artery Papilla of pyramid Renal pelvis Renal pelvis Ureter Minor calyx Ureter Renal pyramid Renal medulla in renal medulla Renal column Renal cortex Fibrous capsule (a) Frontal section, posterior view, illustrating (a) Photograph of right kidney, frontal section (b) Diagrammatic view major blood vessels Copyright © 2011 Pearson Education, Inc. Figure 24.3 Copyright © 2011 Pearson Education, Inc. Figure 24.4a Summary of Blood Vessels Supplying the Internal Gross Anatomy of the Kidneys Kidney Aorta Inferior vena cava Renal artery Renal vein • Nerve supply—renal plexus • A network of autonomic fibers Segmental artery Interlobar vein • An offshoot of the celiac plexus Interlobar artery Arcuate vein • Supplied by sympathetic fibers from Arcuate artery Cortical radiate vein • Lowest thoracic splanchnic nerve Peritubular capillaries Cortical radiate artery and vasa recta • First lumbar splanchnis nerve Afferent arteriole Efferent arteriole Glomerulus (capillaries) Nephron-associated blood vessels (see Figure 24.9) (b) Path of blood flow through renal blood vessels Copyright © 2011 Pearson Education, Inc. Figure 24.4b Copyright © 2011 Pearson Education, Inc. 2 Mechanisms of Urine Production Basic Kidney Functions Afferent arteriole Glomerular • 3 processes involved in forming urine: capillaries Efferent arteriole • Filtration Cortical radiate • Filtrate of blood leaves kidney capillaries artery Glomerular capsule • Reabsorption Rest of renal tubule • Most nutrients, water, and essential ions reclaimed containing filtrate (from tubules to blood caps) Secretion Peritubular • capillary • Active process of removing undesirable molecules (from blood caps to tubules) Three major renal processes To cortical radiate vein Glomerular filtration Tubular resorption Tubular secretion Urine Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Figure 24.5 Nephron Structure The Nephron • Nephron is composed of • Renal corpuscle—first part of nephron • Renal corpuscle • Consists of glomerulus and glomerular • Renal tubule capsule • Glomerulus— a tuft of capillaries • Capillaries of glomerulus are fenestrated • Glomerular (Bowman’s) capsule-- surrounds glomerular capillaries • Parietal layer—simple squamous epithelium • Visceral layer—consists of podocytes Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Filtration Membrane Filtration Membrane • The filtration membrane is the filter that lies • Basement membrane and slit diaphragm between blood in the glomerulus and • Hold back most proteins capsular space • Allow the following molecules through: • Consists of three layers • Water 1. Endothelium of the capillary • Ions 2. Slits between foot processes of • Glucose podocytes • Amino acids 3. Basement membrane • Urea Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. 3 Renal Corpuscle and the Filtration Membrane Renal Corpuscle and the Filtration Membrane Filtration membrane Glomerular capsular space Capillary endothelium Efferent Capillary arteriole Basement membrane Foot processes of podocyte of glomerular capsule Afferent Cytoplasmic extensions arteriole of podocytes Proximal Filtration slits convoluted Glomerular capillary tubule Parietal layer covered by podocyte- Podocyte Filtration of glomerular containing visceral layer cell body slit capsule of glomerular capsule (a) Renal corpuscle Slit Plasma diaphragm Fenestrations Filtrate in (pores) capsular Glomerular space capillary endothelium (podocyte covering Foot processes Foot and basement of podocyte membrane removed) Fenestration processes (b) Glomerular capillary surrounded by podocytes (pore) of podocyte (d) Three parts of the filtration membrane Copyright © 2011 Pearson Education, Inc. Figure 24.6a, b Copyright © 2011 Pearson Education, Inc. Figure 24.6d Renal Tubule Renal Tubule Renal cortex Renal medulla • Filtrate proceeds to renal tubules from glomerulus Renal pelvis Glomerular capsule: parietal layer Ureter Basement • Proximal convoluted tubule (PCT) Kidney membrane Podocyte Nephron loop (aka, Loop of Henle) Renal corpuscle Fenestrated • endothelium of Glomerular capsule Glomerulus the glomerulus Glomerular capsule: visceral layer • Descending limb/ ascending limb Distal convoluted tubule • Thin segment Microvilli Mitochondria • Thick segment Proximal convoluted tubule Highly infolded plasma membrane • Distal convoluted tubule (DCT) Proximal convoluted tubule cells Cortex • Collecting ducts • Receive urine from several nephrons Medulla Thick segment Distal convoluted tubule cells • Play an important role in conserving body fluids Thin segment Nephron loop Descending limb Ascending limb Collecting Nephron loop (thin-segment) cells duct Principal cell Intercalated cell Collecting duct cells Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Figure 24.7 Renal Tubule Micrograph through the Renal Medulla Renal corpuscle Glomerular capsular space Thin segments of nephron Squamous epithelium loop of parietal layer of glomerular capsule Glomerulus Vasa recta with blood cells within Distal convoluted tubules (clear lumens) Collecting ducts Proximal convoluted tubules (fuzzy lumens due to long microvilli) (a) Photomicrograph of renal cortical tissue (165X) (b) Photomicrograph through the renal medulla (215X) Copyright © 2011 Pearson Education, Inc. Figure 24.8a Copyright © 2011 Pearson Education, Inc. Figure 24.8b 4 2 Classes of Nephrons Classes of Nephron Cortical nephron Juxtamedullary nephron • Has short nephron loop and glomerulus • Has long nephron loop and glomerulus further from the corticomedullary junction closer to the corticomedullary junction • Efferent arteriole supplies peritubular capillaries • Efferent arteriole supplies vasa recta Glomerular capillaries Efferent (glomerulus) arteriole Cortical radiate vein Renal Cortical radiate artery • Cortical nephrons (short loops) corpuscle Glomerular (Bowman’s) Afferent arteriole capsule Proximal Collecting duct convoluted Distal convoluted tubule Afferent arteriole tubule • 85% of nephrons Efferent arteriole Peritubular Cortex capillaries • Juxtamedullary nephrons (long loops) Medulla Ascending or thick limb of the Renal nephron loop pelvis • 15% of nephrons Ureter Corticomedullary Arcuate vein junction Kidney Vasa recta • Contribute to kidney’s ability to concentrate Arcuate artery (a) Nephron loop Descending or thin limb of urine nephron loop Afferent arteriole Glomerulus Efferent arteriole Peritubular capillary bed (b) Copyright © 2011 Pearson Education, Inc. Copyright © 2011 Pearson Education, Inc. Figure 24.9 Blood Vessels Associated with Nephrons Blood Vessels Associated with Nephrons • Nephrons associate closely with two capillary • Glomeruli beds • Produce filtrate that becomes urine • Glomerular capillaries