AP Biology Endocrine System, Feedback loops, & Digestive System

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

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 )  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

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

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

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  uric acid = white bird “poop”!

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

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 Regulating the Internal Environment 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 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 ADH = AntiDiuretic Hormone

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!

AP Biology Digestive System

AP Biology Gastrovascular Cavities  Gastrovascular cavities are the digestive systems in simple animals (Cnidarians, Platyhelminthes)  Incomplete Digestive System- one opening

AP Biology Digestion in Alimentary Canals  Complex animals  An “Entrance” and an “Exit”  This is a complete digestive system.  Mouth = site of ingestion  Anus = site of elimination  What phyla have complete digestive tracts?  (Nematoda, Mollusca, Annelida, Arthropoda, Echinodermata, Chordata)

AP Biology Alimentary Canals/Complete Digestive System

AP Biology Absorption Mechanisms Monosaccharides & amino acids are actively transported across plasma membrane of epithelial cells, then from cell into internal environment Figure Page 734 INTESTINAL LUMEN carbohydrates monosaccharides EPITHELIAL CELL INTERNAL ENVIRONMENT proteins amino acids