AP Biology Water Balance & Nitrogenous Waste Removal Kidney Function

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 Overcoming limitations of diffusion  Evolution of exchange systems for systems to support multicellular organisms aa CO 2 NH 3 O2O2 aa CH aa CHO O2O2

AP Biology Osmoregulation  Water balance vs. habitat Why do all land animals have to conserve water?

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

AP Biology Nitrogenous waste disposal  Ammonia (NH 3 )  _________________________  carcinogenic  _________________________  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

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

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

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

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  white bird “poop” = uric acid paste!

AP Biology Mammalian System  Filter solutes out of blood & reabsorb H 2 O + desirable solutes  Key functions filtrate blood filtration reabsorption secretion excretion urine

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

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?

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  _________________ = ball of capillaries  Excretory system  _________________  proximal tubule  descending limb  ascending limb  distal tubule  _________________ 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  ______________  not filtered out  ______________ 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

AP Biology Nephron: Re-absorption Descending limb Ascending limb  Proximal tubule  reabsorbed back into blood  ________________

AP Biology Descending limb Ascending limb Nephron: Re-absorption  Loop of Henle  descending limb  reabsorbed  ___________________  structure structure fits function!

AP Biology Nephron: Re-absorption Descending limb Ascending limb  Loop of Henle  ascending limb  reabsorbed  ___________________  structure structure fits function!

AP Biology Nephron: Re-absorption  Distal tubule  reabsorbed  ______________  HCO 3 -  regulate blood pH

AP Biology Nephron: Reabsorption & Excretion  Collecting duct  reabsorbed  ________________  excretion  ________________  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 Recap…

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?

AP Biology Maintaining Homeostasis

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

AP Biology nephron low Water Balance: Blood Osmolarity blood osmolarity blood pressure/volume ADH increased water reabsorption increase thirst high Endocrine System Control pituitary ADH = AntiDiuretic Hormone

AP Biology H2OH2O H2OH2O H2OH2O Maintaining Water Balance Alcohol suppresses ADH… makes you urinate a lot!  High blood osmolarity level  too many solutes in blood  dehydration, high salt diet  triggers release antidiuretic hormone (ADH)  produced in hypothalamus  stored in pituitary  makes collecting duct more permeability to water  increase water absorption back into blood  more concentrated urine; decrease urination Get more water into blood

AP Biology low Blood Pressure / Volume blood osmolarity blood pressure/volume renin increased water & salt reabsorption high Endocrine System Control angiotensinogen angiotensin nephron adrenal gland aldosterone JGA JGA = JuxtaGlomerular Apparatus Oooooh, zymogen!

AP Biology Maintaining Water Balance  Low blood volume or low blood pressure  JGA releases renin which acts as an enzyme  activates angiotensinogen  angiotensin  angiotensin acts as a hormone  causes arterioles to constrict = raises blood pressure  triggers release of aldosterone from adrenal gland  aldosterone acts as a hormone  increases kidney reabsorption of Na + & H 2 O  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 nephron low Water Balance blood osmolarity blood pressure/volume 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 Don’t get batty… Ask Questions!!