1. Chapter 25
The Urinary System

2. Introduction Cellular metabolism produces wastes
CO2
Urea
Ammonia
Kidneys rid the body of most nitrogenous wastes
Kidneys regulate the chemical make-up of blood

3. General Functions Serves as a blood filter
Toxins, metabolic wastes leave the body in urine
H2O, glucose, and amino acids are returned to blood

4. 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
Human Anatomy, 3rd edition
Prentice Hall, © 2001

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

6. Human Anatomy, 3rd edition
Anatomy of the Kidney
External Anatomy
Hilus
Renal capsule
Renal artery
Renal vein
Ureter
Internal Anatomy
Renal cortex
Renal medulla
Renal pyramids
Renal papilla
Renal pelvis
Calyces
Human Anatomy, 3rd edition
Prentice Hall, © 2001

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

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

9. Human Anatomy, 3rd edition
Structure of a Nephron
2 main structures
Glomerulus
Renal tubule
Bowman’s capsule
Proximal convoluted tubule
Henle’s Loop
Distal convoluted tubule
Collecting duct
Receives urine from nephrons
Delivers final urine product into calyces
Human Anatomy, 3rd edition
Prentice Hall, © 2001

10. The Glomerulus - Filtration
Blood enters glomerulus
Afferent arteriole
Glomerulus filters blood
Forms filtrate
Blood leaves glomerulus
Efferent arteriole
Human Anatomy, 3rd edition
Prentice Hall, © 2001

11. Renal Tubule – Reabsorption & Secretion
Substances move from filtrate into peritubular capillaries
Active transport
Most occurs in proximal convoluted tubule
Secretion
Substances move from peritubular capillaries into filtrate
Control of blood pH

12. Control of Blood Composition
Excretion of nitrogen-containing compounds
Urea
Uric acid
Water and electrolyte balance
Regulated by hormones

13. Summary of Urine Flow Kidneys produce urine Ureters Bladder Urethra
Filtration
Reabsorption
Secretion
Ureters
Bladder
Urethra