1. Human Anatomy, 3rd edition Prentice Hall, © 2001 Human Anatomy Chapter 26 The Urinary System

2. Human Anatomy, 3rd edition Prentice Hall, © 2001 Introduction –Cellular metabolism produces wastes CO 2 Urea Ammonia –Kidneys rid the body of most nitrogenous wastes –Kidneys regulate the chemical make-up of blood

3. Human Anatomy, 3rd edition Prentice Hall, © 2001 General Functions –Serves as a blood filter –Toxins, metabolic wastes leave the body in urine –H 2 O, glucose, and amino acids are returned to blood

4. Human Anatomy, 3rd edition Prentice Hall, © 2001 Organs of the Urinary System –Kidneys (paired) Perform filtering functions and manufacture urine –Ureters (paired) Transport urine –Urinary bladder (single) Stores urine –Urethra (single) Transports urine

5. Human Anatomy, 3rd edition Prentice Hall, © 2001 The Urinary System

6. Human Anatomy, 3rd edition Prentice Hall, © 2001 Location of Kidneys –Lie against the dorsal body wall –Beneath the parietal peritoneum –In the superior lumbar region Protected by the lower part of the rib cage

7. Human Anatomy, 3rd edition Prentice Hall, © 2001 Location of the Kidneys

8. Human Anatomy, 3rd edition Prentice Hall, © 2001 External Structure of the Kidney –Hilus –Renal capsule –Renal artery –Renal vein –Ureter

9. Human Anatomy, 3rd edition Prentice Hall, © 2001 Internal Structure of the Kidney –Renal cortex –Renal medulla Renal pyramids Renal papilla –Renal pelvis –Calyces

10. Human Anatomy, 3rd edition Prentice Hall, © 2001 Structure of the Kidney

11. Human Anatomy, 3rd edition Prentice Hall, © 2001 Blood Supply of the Kidney –Approximately ¼ of the total blood supply of the body passes through the kidneys each minute –Renal artery branches inside the kidney Supplies the pyramids and the cortex –Venous blood leaves the cortex and medulla Small veins join the renal vein

12. Human Anatomy, 3rd edition Prentice Hall, © 2001 Blood Supply of the Kidney

13. Human Anatomy, 3rd edition Prentice Hall, © 2001 Blood Supply of the Kidney

14. Human Anatomy, 3rd edition Prentice Hall, © 2001 Nephrons and Urine Formation – Nephrons form the urine product Filtration Reabsorption Secretion –Each kidney contains about 1 million nephrons

15. Human Anatomy, 3rd edition Prentice Hall, © 2001 Structure of a Nephron –2 main structures Glomerulus – a knot of capillaries Renal tubule –Bowman’s capsule surrounds the glomerulus –Proximal convoluted tubule –Henle’s Loop –Distal convoluted tubule –Renal tubule enters collecting duct Receives urine from nephrons Delivers final urine product into the calyces

16. Human Anatomy, 3rd edition Prentice Hall, © 2001 A Renal Corpuscle

17. Human Anatomy, 3rd edition Prentice Hall, © 2001 Renal Corpuscles

18. Human Anatomy, 3rd edition Prentice Hall, © 2001 A Typical Nephron

19. Human Anatomy, 3rd edition Prentice Hall, © 2001 A Typical Nephron

20. Human Anatomy, 3rd edition Prentice Hall, © 2001 Blood Supply of the Nephron

21. Human Anatomy, 3rd edition Prentice Hall, © 2001 Urine Formation –Filtration Blood in afferent arteriole is under high pressure Glomerulus acts as a filter Filtrate = the substance that is filtered from the blood into the renal tubule Blood leaves the glomerulus through the efferent arteriole –Reabsorption Filtrate contains useful substances (as well as wastes) which are returned to the blood Most depends on active transport –Transported into peritubular capillaries –Most occurs in the proximal convoluted tubule –Secretion Substances move from cells or blood (peritubular capillaries) into the filtrate Important in controlling pH of blood

22. Human Anatomy, 3rd edition Prentice Hall, © 2001 Control of Blood Composition –Excretion of nitrogen-containing compounds Urea Uric acid –Water and electrolyte balance Regulated by hormones

23. Human Anatomy, 3rd edition Prentice Hall, © 2001 Summary of Urine Flow –Kidneys produce urine Filtration Reabsorption Secretion –Ureters –Bladder –Urethra