1. Excretory and Urinary System Notes Chapter 15

2. Functions of the Urinary System Slide 15.1a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Elimination of waste products  Nitrogenous wastes  Toxins  Drugs

3. Functions of the Urinary System Slide 15.1b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Regulate aspects of homeostasis  Water balance  Electrolytes  Acid-base balance in the blood  Blood pressure  Red blood cell production  Activation of vitamin D

4. Organs of the Urinary system Slide 15.2 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Kidneys  Ureters  Urinary bladder  Urethra Figure 15.1a

5. Location of the Kidneys p 481 Slide 15.3 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Against the dorsal body wall  At the level of T 12 to L 3  The right kidney is slightly lower than the left  Attached to ureters, renal blood vessels, and nerves at renal hilus  Atop each kidney is an adrenal gland

6. Coverings of the Kidneys Slide 15.4 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Renal capsule  Surrounds each kidney  Adipose capsule  Surrounds the kidney  Provides protection to the kidney  Helps keep the kidney in its correct location

7. Regions of the Kidney p 482 Slide 15.5 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Renal cortex – outer region  Renal medulla – inside the cortex  Renal pelvis – inner collecting tube Figure 15.2b

8. Ureters Slide 15.20 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Slender tubes attaching the kidney to the bladder  Continuous with the renal pelvis  Enter the posterior aspect of the bladder  Runs behind the peritoneum  Peristalsis aids gravity in urine transport

9. Urinary Bladder Slide 15.21a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Smooth, collapsible, muscular sac  Temporarily stores urine Figure 15.6

10. Urinary Bladder Wall Slide 15.22 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Three layers of smooth muscle (detrusor muscle)  Mucosa made of transitional epithelium  Walls are thick and folded in an empty bladder  Bladder can expand significantly without increasing internal pressure

11. Urethra Slide 15.23 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings  Thin-walled tube that carries urine from the bladder to the outside of the body by peristalsis  Release of urine is controlled by two sphincters  Internal urethral sphincter (involuntary)  External urethral sphincter (voluntary)

12. Nephron Function – “functional unit of the kidney” Three Processes – Page 486 1. Filtration (blood to capsule) 2. Reabsorption (return to blood) 3. Excreted products (added to urine)

13. Filtration p 487 Urine formation occurs in millions of units called nephrons. 1. Unfiltered blood enters the renal artery into smaller arterioles. 2. Blood then enters the glomerulus – mass of capillaries where blood is filtered. 3. Large molecules – red and white blood cells, platelets, plasma proteins, and fats stay in the glomerulus and return through smaller venules into the renal vein 4. Smaller molecules – water, amino acids, salt, glucose, and urea get filtered into the Bowman’s Capsule and travels into the tubules, eventually into the collecting duct

15. Reabsorption 1. Too much is filtered so amino acids, sugars, and water are reabsorbed depending on what is needed by the body 2. Urine- what’s left over – urea, uric acid, excess water and salt

16. Excreted Products Through the process of excretion, almost 100% of nutrients are reabsorbed and essentially all wastes are excreted. Ammonia is extremely toxic to the body and must be constantly flushed from the system

17. Other excretory organs Skin – (Perspiration) – get rid of water, salts, and urea. Lungs – Respiration – excrete CO2 Liver – forms urea when producing bile