2. AP Biology Osmoregulation Why do all land animals have to conserve water?  always lose water (breathing & waste)  may lose life while searching for water  Water balance vs. Habitat  freshwater  hypotonic to body fluids  water flow into cells & salt loss  saltwater  hypertonic to body fluids  water loss from cells  land  dry environment  need to conserve water  may also need to conserve salt hypotonic hypertonic

3. AP Biology Intracellular Waste  What waste products are made inside of cells?  what do we digest our food into…  proteins = CHON  nucleic acids = CHOPN CO 2 + H 2 O NH 2 = ammonia  CO 2 + H 2 O + N  CO 2 + H 2 O + P + N | ||| H H N C–OH O R H –C– lots! very little

4. AP Biology Nitrogenous waste disposal  Ammonia (NH 3 )  very toxic  carcinogenic  very soluble  easily crosses membranes  must dilute it & get rid of it… fast!  How you get rid of nitrogenous wastes depends on  who you are (evolutionary relationship)  where you live (habitat) aquaticterrestrialterrestrial egg layer

5. AP Biology Nitrogen waste  Aquatic organisms  can afford to lose water  ammonia  most toxic  Terrestrial  need to conserve water  urea  less toxic  Terrestrial egg layers  need to conserve water  need to protect embryo in egg  uric acid  least toxic

6. AP Biology Freshwater animals  Hypotonic environment  water diffuses into cells  Manage water & waste together  remove surplus water & waste  use surplus water to dilute ammonia & excrete it  also diffuse ammonia continuously through gills  overcome loss of salts  reabsorb in kidneys or active transport across gills

7. AP Biology Land animals  Nitrogen waste disposal on land  need to conserve water  urea = larger molecule = less soluble = less toxic- produced in liver  kidney  filter solutes out of blood  reabsorb H 2 O (+ any useful solutes)  excrete waste  urine = urea, salts, excess sugar & H 2 O urine is very concentrated concentrated NH 3 would be too toxic O C H N H H N H mammals

8. AP Biology Egg-laying land animals  Nitrogen waste disposal in egg  no place to get rid of waste in egg  need even less soluble molecule  uric acid = BIGGER = less soluble = less toxic  birds, reptiles, insects

9. AP Biology N N N N O H O O H H H Uric acid  Polymerized urea  large molecule  precipitates out of solution  doesn’t harm embryo in egg  white dust in egg  adults still excrete N waste as white paste  no liquid waste  uric acid = white bird “poop”!

10. AP Biology Mammalian System  Filter solutes out of blood & reabsorb H 2 O + desirable solutes  Key functions  filtration  fluids (water & solutes) filtered out of blood  reabsorption  selectively reabsorb (diffusion) needed water + solutes back to blood  secretion  pump out any other unwanted solutes to urine  excretion  expel concentrated urine (N waste + solutes + toxins) from body bloodfiltrate concentrated urine

11. AP Biology Nephron: Filtration  At glomerulus  filtered out of blood H2OH2O  glucose  salts / ions (Na + / Cl – )  urea  not filtered out  cells  proteins high blood pressure in kidneys force to push (filter) H 2 O & solutes out of blood vessel

12. AP Biology Nephron: Re-absorption  Proximal tubule  reabsorbed back into blood  NaCl  active transport of Na +  Cl – follows by diffusion H2OH2O  glucose  HCO 3 -  bicarbonate  buffer for blood pH

13. AP Biology Nephron: Re-absorption  Loop of Henle  descending limb  reabsorbed H2OH2O  structure  many aquaporins in cell membranes  high permeability to H 2 O  no Na + or Cl – channels  impermeable to salt

14. AP Biology Nephron: Re-absorption  Loop of Henle  ascending limb  reabsorbed  Na + & Cl –  structure  many Na + / Cl – channels in cell membranes  high permeability to Na + & Cl –  no aquaporins  impermeable to H 2 O

15. AP Biology Nephron: Re-absorption  Distal tubule  reabsorbed  salts H2OH2O  bicarbonate  HCO 3 -  regulate blood pH

16. AP Biology Nephron: Reabsorption & Excretion  Collecting duct  reabsorbed  H 2 O = through aquaporins  excretion  concentrated urine  to bladder  impermeable lining = no channels in cell membranes