2. AP Biology 2008-2009 Excretory System Kidneys and the Urinary System, Lungs, Skin, & Liver (removing metabolic waste)

3. Regents Biology Unicellular  Multicellular All cells in direct contact with environment All cells can easily get nutrients in & waste out by diffusion Internal cells not in direct contact with environment Internal cells can’t get nutrients in & waste out Need organ systems Warm, dilute ocean waters Warm, dilute ocean waters UnicellularMulticellular Limits cell size - Must stay small

4. Regents Biology What liquid waste do we make?  Digesting protein makes poison  nitrogen waste = ammonia = poison H CO 2 + H 2 O NH 2 = ammonia H H N C—OH || O H | —C— | AMINO ACIDs and Nitrogen Bases

5. Regents Biology  The kind of waste you make depends on where you live  Freshwater  Ammonia  Diffuse and dilute quickly  Land  Urea  Humans  Egg layer/Insects  uric acid  Solid – crystals  LEAST toxic Nitrogen waste

6. Regents Biology Human Excretory System  Mammals have a pair of bean-shaped kidneys  supplied with blood by a renal artery and a renal vein Organ system Organ Tissue Nephron

7. Regents Biology Bladder

8. Regents Biology Nephron = functional unit of kidney  Not filtered out  cells and proteins (too big)  Filtered out  “Bad” stuff  Urea (from liver)  Salts H2OH2O  toxins from food  “Good” stuff  simple sugars, aa  “Good” stuff reabsorbed; “Bad” stuff makes urine  to bladder

9. Regents Biology Nephron Structure – functional unit Renal FILTRATION Removes “good” and “bad” stuff NO Cells leave the blood vessels REABSORPTION Reabsorb “good” stuff” (ss, aa, some salt and some water to maintain water balance) Capillaries – wrapped around loop to increase surface area Ball of capillaries Bowman’s capsule

10. Regents Biology Also Skin – removes salt, water, and urea called sweat Lungs – remove CO2 and water Liver – PRODUCES UREA Diseases/Disorders – failure to maintain homeostasis Kidney Disease – failure of kidneys to filter toxins from blood; treatment =dialysis or transplant Nephritis – inflammation of kidneys Kidney stone – calcium deposit that blocks ureter Gout – build up of uric acid in joints