The Excretory System Elimination of wastes

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

Sponges & Cnidarians Diffusion

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

Roundworms Excretory tube collects waste and sends to the outside

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

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

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

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

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!

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

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

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

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

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

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

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.

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