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Chapter 44 - Class Presentation


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Chapter 44 - Class Presentation

  1. 1. Regulating the Internal EnvironmentAP Biology 2006-2007
  2. 2. 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 thermoregulation osmoregulation regulator regulatorAP Biology conformer conformer
  3. 3. 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” conditionAP Biology
  4. 4. Regulating the Internal Environment Water Balance & Nitrogenous Waste RemovalAP Biology 2006-2007
  5. 5. Animal systems evolved to support multicellular life aa CH O2 CO2 CHO aa NH3 CHO O2 O2 CH aa intracellular CO2 waste CO2 NH3 O2 aa NH3 CO2 NH3 CO2 CO2 NH3O2 NH3 CO2 CO2 CO2 aa NH3 NH3 NH3 CO2 CO2 CHO CH aa extracellularAP Biology Diffusion too slow! waste
  6. 6. Overcoming limitations of diffusion  Evolution of exchange systems for  distributing nutrients  circulatory system CO2  removing wastes CO2 NH3 O2 aa NH3 CO2  excretory system NH3 CO2 CO2 NH3 O2 NH3 CO2 CO2 CO2 aa NH3 NH3 NH3 systems to support CO2 CO2 CHO multicellular organisms CH aaAP Biology
  7. 7. hypotonic Osmoregulation  Water balance  freshwater  hypotonic  water flow into cells & salt loss  saltwater  hypertonic  water loss from cells hypertonic  land  dry environment  need to conserve water  may also need to conserve saltWhy do all land animals have to conserve water? always lose water (breathing & waste)AP Biology life while searching for water may lose
  8. 8. Animals poison themselves Intracellular Waste from the inside by digesting proteins!  What waste products?  what do we digest our food into…  carbohydrates = CHO  CO2 + H2O lots!  lipids = CHO  CO2 + H2O very little  proteins = CHON  CO2 + H2O + N  nucleic acids = CHOPN  CO2 + H2O + P + Ncellular digestion… cellular waste H O | || H CO2 + H2O N –C– C–OH NH2 = H |ammonia AP Biology R
  9. 9. Nitrogenous waste disposal  Ammonia (NH3)  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)aquatic AP Biology terrestrial terrestrial egg layer
  10. 10. 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 acidAP Biology  least toxic
  11. 11. 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 gillsAP Biology
  12. 12. H Land animals H N C O  Nitrogen waste disposal on land H H N  need to conserve water  must process ammonia so less toxic  urea = larger molecule = less soluble = less toxic  2NH2 + CO2 = urea Urea  produced in liver costs energy  kidney to synthesize, but it’s worth it!  filter solutes out of blood  reabsorb H2O (+ any useful solutes)  excrete waste  urine = urea, salts, excess sugar & H2O  urine is very concentrated  concentrated NH3 would be too toxicAP Biology mammals
  13. 13. 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 itty bitty living space!AP Biology
  14. 14. 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 O  uric acid = white bird “poop”! HH N N OO N NAP Biology H H
  15. 15. Mammalian System blood filtrate  Filter solutes out of blood & reabsorb H2O + 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 + concentratedAP Biology solutes + toxins) from body urine
  16. 16. Mammalian Kidney inferior aortavena cava adrenal gland kidney nephro n ureter renal vein & artery epithelial cells bladder urethra AP Biology
  17. 17. 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 why selective reabsorption  selective reabsorption of & not selective valuable solutes & H2O filtration? back into bloodstream “counter currentAP Biology  greater flexibility & control exchange system”
  18. 18. How can different sections Mammalian kidney allow the diffusion of different  Interaction of circulatory molecules? & excretory systems  Circulatory system Bowman’s Proximal tubule Distal capsule tubule  glomerulus = Glomerulus ball of capillaries  Excretory system  nephron Glucose H2O Na+ Cl- Amino  Bowman’s capsule acids H2O H2O Na+ Cl- Mg++ Ca++ H2O  loop of Henle H2O  proximal tubule  descending limb H2O  ascending limb Collecting duct Loop of Henle  distal tubule AP Biology collecting duct
  19. 19. Nephron: Filtration  At glomerulus  filtered out of blood  H2O  glucose  salts / ions  urea  not filtered out high blood pressure in kidneys  cells force to push (filter) H2O & solutes  proteins out of blood vessel BIG problems when you start out with high blood pressure in systemAP Biology hypertension = kidney damage
  20. 20. Nephron: Re-absorption  Proximal tubule  reabsorbed back into blood  NaCl  active transport of Na+  Cl– follows by diffusion  H2O Descending Ascending  glucose limb limb  HCO3-  bicarbonate  buffer for blood pHAP Biology
  21. 21. Nephron: Re-absorption structure fits  Loop of Henle function!  descending limb  high permeability to H2O  many aquaporins in cell membranes  low permeability to Descending Ascending salt limb limb  few Na+ or Cl– channels  reabsorbed  H2OAP Biology
  22. 22. Nephron: Re-absorption structure fits  Loop of Henle function!  ascending limb  low permeability to H2O  Cl- pump  Na+ follows by diffusion  different membrane Descending limb Ascending limb proteins  reabsorbed  salts  maintains osmoticAP Biology gradient
  23. 23. Nephron: Re-absorption  Distal tubule  reabsorbed  salts  H2O  HCO3-  bicarbonateAP Biology
  24. 24. Nephron: Reabsorption & Excretion  Collecting duct  reabsorbed  H2O  excretion  concentrated urine passed to bladder Descending Ascending limb limb  impermeable liningAP Biology
  25. 25. 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 systemAP Biology
  26. 26. why Summary selective reabsorption & not selective filtration?  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  Excreted  urea  excess H2O u excess solutes (glucose, salts)AP Biology toxins, drugs, “unknowns”
  27. 27. Any Questions?AP Biology 2006-2007
  28. 28. Regulating the Internal Environment Maintaining HomeostasisAP Biology 2006-2007
  29. 29. Negative Feedback Loop hormone or nerve signal lowers gland or nervous system body condition (return to set point) high sensor specific body condition sensor low raises body condition gland or nervous system (return to set point)AP Biology hormone or nerve signal
  30. 30. Nervous System Control Controlling Body Temperature nerve signals brain sweat dilates surface blood vessels high body temperature lowconstricts surface shiver brain blood vessels AP Biology nerve signals
  31. 31. Endocrine System Control Blood Osmolarity ADH pituitary increased increase water thirst reabsorption high nephron blood osmolarity blood pressure low ADH = AntiDiuretic HormoneAP Biology
  32. 32. Maintaining Water Balance Get more  High blood osmolarity level water into  too many solutes in blood blood fast  dehydration, high salt diet  stimulates thirst = drink more  release ADH from pituitary gland  antidiuretic hormone  increases permeability of collecting duct H2O & reabsorption of water in kidneys H2O  increase water absorption back into blood  decrease urination H2O Alcohol suppresses ADH… makes you urinate a lot!AP Biology
  33. 33. Endocrine System Control Blood Osmolarity Oooooh, zymogen! JGA = JuxtaGlomerular high Apparatus blood osmolarity blood pressure low JGA increasedadrenal water & salt nephron gland reabsorption in kidney renin aldosterone angiotensinogen AP Biology angiotensin
  34. 34. Maintaining Water Balance Get more  Low blood osmolarity level water & salt into or low blood pressure blood fast!  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 & H2O in kidneys  puts more water & salts back in blood adrenal gland Why such a rapid response system? Spring a leak?AP Biology
  35. 35. Endocrine System Control Blood Osmolarity ADH pituitary increased increase water thirst reabsorption high nephron blood osmolarity blood pressure JuxtaGlomerular low Apparatus increasedadrenal water & salt nephron gland reabsorption renin aldosterone angiotensinogen AP Biology angiotensin
  36. 36. Don’t get batty… Ask Questions!!AP Biology 2006-2007