1. The Excretory System
Elimination of wastes

2. How do organisms get rid of wastes???
Bacteria – diffusion
Protists – diffusion
Fungi – diffusion
Plants – diffusion through stomata

3. Sponges & Cnidarians
Diffusion

4. Flatworms Diffusion for most waste
“Flame cells” help with waste removal and water level control

5. Roundworms
Excretory tube collects waste and sends to the outside

6. Segmented Worms & Mollusks
Have 2 nephridia per segment that remove waste from body fluid. Waste moves though tubes and leaves through a pore

7. Arthropods
Malphigian Tubules – remove nitrogenous waste from blood and nearby tissues
Digestive waste – Moves through digestive pathway and is exits through rectum

8. Echinoderms
Wastes move into water vascular system and exit through the anus on top

9. Fish & Amphibians Undigested food exits the body through the cloaca
2 Kidneys filter waste from the blood
Gills

11. Reptiles & Birds
Kidneys and excretory pathway are similar to fish and amphibians, except reptiles and birds excrete uric acid in a thick pasty material to conserve water!

12. Mammals
Have 2 kidneys that filter waste from the blood every 45 mins

13. II. Human Excretory System
A. Function – removes wastes, such as urea, from the body

14. B. Excretory organs
1. Kidneys – (2) remove waste and extra salts, drugs, sugars, and water from the blood a. contains many nephrons – filtering units

15. B. Excretory organs (continued)
2. Ureters – 2 tubes that carry wastes from each kidney to the bladder 3. Bladder – temporary storage of urine 4. Urethra – empties urine from body

17. The Urinary System Section 38-3 Artery Vein Kidney (Cross Section)
Cortex
Medulla
Ureter
Urinary bladder
Urethra

18. Figure 38-17 Structure of the Kidneys
Section 38-3
Kidney
Nephron
Cortex
Medulla
Renal artery
Renal vein
Ureter
To the bladder
Bowman’s capsule
Glomerulus
Capillaries
Collecting duct
To the ureter
Loop of Henle
Artery
Vein

19. The Nephron Reabsorption Filtration Section 38-3
As the filtrate flows through the renal tubule, most of the water and nutrients are reabsorbed into the blood. The concentrated fluid that remains is called urine.
Filtration
Most filtration occurs in the glomerulus. Blood pressure forces water, salt, glucose, amino acids, and urea into Bowman’s capsule. Proteins and blood cells are too large to cross the membrane; they remain in the blood. The fluid that enters the renal tubules is called the filtrate.

20. Figure 38-19 Kidney Dialysis
Section 38-3
Blood in tubing flows through dialysis fluid
Blood pump
Vein
Artery
Shunt
Used dialysis fluid
Air detector
Dialysis machine
Fresh dialysis fluid
Compressed air