2. AP Biology 2006-2007 Regulating the Internal Environment

3. AP Biology Conformers vs. Regulators  Two evolutionary paths for organisms  regulate internal environment  maintain relatively constant internal conditions  conform to external environment  allow internal conditions to fluctuate along with external changes conformer thermoregulation regulator conformer osmoregulation regulator

4. AP Biology Homeostasis  Keeping the balance  animal body needs to coordinate many systems all at once  temperature  blood sugar levels  energy production  water balance & intracellular waste disposal  nutrients  ion balance  cell growth  maintaining a “steady state” condition

5. AP Biology 2006-2007 Regulating the Internal Environment Water Balance & Nitrogenous Waste Removal

6. AP Biology intracellular waste extracellular waste Animal systems evolved to support multicellular life O2O2 CHO aa CH CO 2 NH 3 aa O2O2 CH O2O2 aa CO 2 NH 3 O2O2 aa CH aa CHO O2O2 Diffusion too slow!

7. AP Biology Overcoming limitations of diffusion  Evolution of exchange systems for  distributing nutrients  circulatory system  removing wastes  excretory system systems to support multicellular organisms aa CO 2 NH 3 O2O2 aa CH aa CHO O2O2

8. 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  freshwater  hypotonic  water flow into cells & salt loss  saltwater  hypertonic  water loss from cells  land  dry environment  need to conserve water  may also need to conserve salt hypotonic hypertonic

9. AP Biology Intracellular Waste  What waste products?  what do we digest our food into…  carbohydrates = CHO  lipids = CHO  proteins = CHON  nucleic acids = CHOPN CO 2 + H 2 O NH 2 = ammonia  CO 2 + H 2 O  CO 2 + H 2 O + N  CO 2 + H 2 O + P + N | ||| H H N C–OH O R H –C– Animals poison themselves from the inside by digesting proteins! lots! very little cellular digestion… cellular waste

10. 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

11. 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

12. AP Biology Freshwater animals  Water removal & nitrogen waste disposal  remove surplus water  use surplus water to dilute ammonia & excrete it  need to excrete a lot of water so dilute ammonia & excrete it as very dilute urine  also diffuse ammonia continuously through gills or through any moist membrane  overcome loss of salts  reabsorb in kidneys or active transport across gills

13. AP Biology Land animals  Nitrogen waste disposal on land  need to conserve water  must process ammonia so less toxic  urea = larger molecule = less soluble = less toxic  2NH 2 + CO 2 = urea  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 Urea costs energy to synthesize, but it’s worth it! mammals

14. AP Biology Egg-laying land animals itty bitty living space!  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

15. AP Biology N N N N O H O O H H H Uric acid And that folks, is why most male birds don’t have a penis!  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”!

16. 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

17. AP Biology Mammalian Kidney kidney bladder ureter urethra renal vein & artery nephro n epithelial cells adrenal gland inferior vena cava aorta

18. AP Biology Nephron  Functional units of kidney  1 million nephrons per kidney  Function  filter out urea & other solutes (salt, sugar…)  blood plasma filtered into nephron  high pressure flow  selective reabsorption of valuable solutes & H 2 O back into bloodstream  greater flexibility & control “counter current exchange system” why selective reabsorption & not selective filtration?

19. AP Biology Mammalian kidney Proximal tubule Distal tubule Glomerulus Collecting duct Loop of Henle Amino acids Glucose H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O H2OH2O Na + Cl - Mg ++ Ca ++  Interaction of circulatory & excretory systems  Circulatory system  glomerulus = ball of capillaries  Excretory system  nephron  Bowman’s capsule  loop of Henle  proximal tubule  descending limb  ascending limb  distal tubule  collecting duct How can different sections allow the diffusion of different molecules? Bowman’s capsule Na + Cl -

20. AP Biology Nephron: Filtration  At glomerulus  filtered out of blood H2OH2O  glucose  salts / ions  urea  not filtered out  cells  proteins high blood pressure in kidneys force to push (filter) H 2 O & solutes out of blood vessel BIG problems when you start out with high blood pressure in system hypertension = kidney damage

21. AP Biology Nephron: Re-absorption Descending limb Ascending limb  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

22. AP Biology Descending limb Ascending limb Nephron: Re-absorption  Loop of Henle  descending limb  high permeability to H 2 O  many aquaporins in cell membranes  low permeability to salt  few Na + or Cl – channels  reabsorbed H2OH2O structure fits function!

23. AP Biology Nephron: Re-absorption Descending limb Ascending limb  Loop of Henle  ascending limb  low permeability to H 2 O  Cl - pump  Na + follows by diffusion  different membrane proteins  reabsorbed  salts  maintains osmotic gradient structure fits function!

24. AP Biology Nephron: Re-absorption  Distal tubule  reabsorbed  salts H2OH2O  HCO 3 -  bicarbonate

25. AP Biology Nephron: Reabsorption & Excretion  Collecting duct  reabsorbed H2OH2O  excretion  concentrated urine passed to bladder  impermeable lining Descending limb Ascending limb

26. AP Biology Osmotic control in nephron  How is all this re-absorption achieved?  tight osmotic control to reduce the energy cost of excretion  use diffusion instead of active transport wherever possible the value of a counter current exchange system

27. AP Biology Summary  Not filtered out  cells u proteins  remain in blood (too big)  Reabsorbed: active transport  Na + u amino acids  Cl – u glucose  Reabsorbed: diffusion  Na + u Cl – H2OH2O  Excreted  urea  excess H 2 O u excess solutes (glucose, salts)  toxins, drugs, “unknowns” why selective reabsorption & not selective filtration?

28. AP Biology 2006-2007 Any Questions?

29. AP Biology 2006-2007 Regulating the Internal Environment Maintaining Homeostasis

30. AP Biology sensor Negative Feedback Loop high low hormone or nerve signal lowers body condition (return to set point) hormone or nerve signal gland or nervous system raises body condition (return to set point) gland or nervous system sensor specific body condition

31. AP Biology Controlling Body Temperature high low nerve signals sweat nerve signals brain body temperature shiver brain dilates surface blood vessels constricts surface blood vessels Nervous System Control

32. AP Biology nephron low Blood Osmolarity blood osmolarity blood pressure ADH increased water reabsorption increase thirst high Endocrine System Control pituitary ADH = AntiDiuretic Hormone

33. AP Biology H2OH2O H2OH2O H2OH2O Maintaining Water Balance Get more water into blood fast Alcohol suppresses ADH… makes you urinate a lot!  High blood osmolarity level  too many solutes in blood  dehydration, high salt diet  stimulates thirst = drink more  release ADH from pituitary gland  antidiuretic hormone  increases permeability of collecting duct & reabsorption of water in kidneys  increase water absorption back into blood  decrease urination

34. AP Biology low Blood Osmolarity blood osmolarity blood pressure renin increased water & salt reabsorption in kidney high Endocrine System Control angiotensinogen angiotensin nephron adrenal gland aldosterone JGA JGA = JuxtaGlomerular Apparatus Oooooh, zymogen!

35. AP Biology Maintaining Water Balance  Low blood osmolarity level or low blood pressure  JGA releases renin in kidney  renin converts angiotensinogen to angiotensin  angiotensin causes arterioles to constrict  increase blood pressure  angiotensin triggers release of aldosterone from adrenal gland  increases reabsorption of NaCl & H 2 O in kidneys  puts more water & salts back in blood Get more water & salt into blood fast! adrenal gland Why such a rapid response system? Spring a leak?

36. AP Biology nephron low Blood Osmolarity blood osmolarity blood pressure ADH increased water reabsorption increase thirst renin increased water & salt reabsorption high Endocrine System Control pituitary angiotensinogen angiotensin nephron adrenal gland aldosterone JuxtaGlomerular Apparatus

37. AP Biology 2006-2007 Don’t get batty… Ask Questions!!