AP Biology Regulating the Internal Environment

AP Biology Conformers vs. Regulators  2 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 regulato r conformer osmoregulation regulato r

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

AP Biology Regulating the Internal Environment Water Balance & Nitrogenous Waste Removal

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!

AP Biology Solving exchange problem  Evolve of exchange systems for  distributing nutrients  circulatory system  removing wastes  excretory system overcoming the limitations of diffusion aa CO 2 NH 3 O2O2 aa CH aa CHO O2O2

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 need to conserve salt

AP Biology Waste disposal  What waste products?  what do we digest our food into…  carbohydrates = CHO  lipids = CHO  proteins = CHON  nucleic acids = CHOPN  relatively small amount in cell 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! cellular digestion… cellular waste

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)

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

AP Biology Freshwater animals  Water removal & nitrogen waste disposal  surplus of water  can dilute ammonia & excrete it  need to excrete a lot of water anyway so excrete very dilute urine  pass ammonia continuously through gills or through any moist membrane  loss of salts  reabsorb in kidneys or active transport across gills

AP Biology Land animals  Nitrogen waste disposal on land  evolved less toxic waste product  need to conserve water  urea = less soluble = less toxic  kidney  filter wastes out of blood  reabsorb H 2 O  excrete waste  urine = urea, salts, excess sugar & H 2 O urine is very concentrated concentrated NH 3 would be too toxic

AP Biology Urea  Larger molecule = less soluble  2NH 2 + CO 2 = urea  combined in liver  Requires energy to produce  worth the investment of energy  Filtered out by kidneys  collected from cells by circulatory system H H N H H N CO

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 itty bitty living space!

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 excrete white paste  no liquid waste  white bird “poop”! And that folks, is why a male bird doesn’t have a penis!

AP Biology Mammalian System  Key functions  filtration  fluids from blood collected  includes water & solutes  reabsorption  selectively reabsorb needed substances back to blood  secretion  pump out unwanted substances to urine  excretion  remove excess substances & toxins from body bloodfiltrate urine

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

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

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  descending limb  ascending limb  collecting duct How can different sections allow the diffusion of different molecules? Bowman’s capsule Na + Cl -

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 H 2 O & solutes out of blood vessel BIG problems when you start out with high blood pressure in system hypertension = kidney damage

AP Biology Nephron: Re-absorption Descending limb Ascending limb  Proximal tubule  reabsorbed  NaCl  active transport Na +  Cl - follows by diffusion H2OH2O  glucose  HCO 3 -  bicarbonate  buffer for blood pH

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  reabsorbed H2OH2O structure fits function!

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!

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

AP Biology Nephron: Reabsorption & Excretion  Collecting duct  reabsorbed H2OH2O  excretion  urea passed through to bladder Descending limb Ascending limb

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

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

AP Biology Any Questions?

AP Biology Regulating the Internal Environment Regulation of Homeostasis

AP Biology Sensor constantly monitors conditions Negative feedback loop completed Response Return to set point Stimulus deviation from set point Perturbing factor Effector causes changes to compensate for deviation Integrating center compares conditions to set point Negative Feedback Loop  Maintaining homeostasis

AP Biology sensor Negative Feedback Model high low hormone 1 lowers body condition (return to set point) hormone 2 gland raises body condition (return to set point) gland sensor specific body condition

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

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

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  anti-diuretic hormone  increases permeability of collecting duct & reabsorption of water in kidneys  increase water absorption back into blood  decrease urination

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

AP Biology Maintaining Water Balance Low solutes renin (from JGA) activates angiotensinogen angiotensin triggers aldosterone aldosterone increases absorption of NaCl & H 2 O in kidney Oooooh, zymogen!  Low blood osmolarity level or low blood pressure

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?

AP Biology Don’t get batty… Ask Questions!!

AP Biology Homeostasis  Osmoregulation  solute balance & gain or loss of water  Excretion  elimination of nitrogenous wastes  Thermoregulation  maintain temperature within tolerable range

AP Biology Maintaining Water Balance  Monitor blood osmolarity  amount of dissolved material in blood in brain ADH = anti-diuretic hormone High solutes