Regulating the Internal Environment

1. Regulating the InternalEnvironment Water Balance & Nitrogenous Waste Removal

2. Conformers vs. Regulators • Two evolutionary paths for organisms • Endothermy • maintain relatively constant internal conditions • Ectothermy • allow internal conditions to fluctuate along with external changes osmoregulation thermoregulation regulator regulator conformer conformer

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” condition

4. aa O2 CH CHO CO2 aa NH3 CHO O2 CH O2 aa CO2 CO2 O2 NH3 aa NH3 CO2 NH3 CO2 CO2 NH3 NH3 O2 CO2 CO2 CO2 NH3 aa NH3 NH3 CHO CO2 CO2 aa CH Animal systems evolved to support multicellular life intracellular waste extracellular waste Diffusion too slow!

5. CO2 CO2 O2 NH3 aa NH3 CO2 NH3 CO2 CO2 NH3 NH3 O2 CO2 CO2 CO2 NH3 aa NH3 NH3 CHO CO2 CO2 aa CH Overcoming limitations of diffusion • Evolution of exchange systems for • distributing nutrients • Circulatory • removing wastes • Excretory systems to support multicellular organisms

6. Osmoregulation hypotonic • 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 hypertonic Why do all land animals have to conserve water?

7. H O H | | | –C– C–OH N | H R Intracellular Waste • What waste products? • what do we digest our food into… • carbohydrates = CHO • lipids = CHO • proteins = CHON • nucleic acids = CHOPN  CO2 +H2O lots!  CO2 +H2O verylittle  CO2 +H2O + N  CO2 +H2O + P + N CO2 + H2O NH2= ammonia

8. Nitrogenous waste disposal • Ammonia (NH3) • 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) aquatic terrestrial terrestrial egg layer

9. Nitrogen waste • Aquatic animals • can afford to lose water • _Ammonia_______ • most toxic • Terrestrial Animals • need to conserve water • _Urea___________ • less toxic • Terrestrial Egg Layers • need to conserve water • need to protectembryo in egg • _Uric Acid______ • least toxic

10. 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

11. H H H H N N C O Land animals • Nitrogen waste disposal on land • need to conserve water • must process ammonia so less toxic • Urea = larger molecule = less soluble = less toxic • 2NH2 + CO2 = urea • produced in liver • Kidney_______ • 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 toxic mammals

12. 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

13. O O O N N N N H H H H Uric acid • Polymerized urea • large molecule • Requires more energy to make • Relatively non-toxic • doesn’t harm embryo in egg • white dust in egg • adults excrete N waste as white paste • no liquid waste • urea = white bird “poop”!

14. Mammalian System blood filtrate • Filter solutes out of blood & reabsorb H2O + desirable solutes • Key functions • Filtration • fluids (water & solutes) filtered outof blood • Reabsorption • selectively reabsorb (diffusion) needed water + solutes back to blood • Secretion • pump out any other unwanted solutes to urine • Excreation • expel concentrated urine (N waste + solutes + toxins) from body concentratedurine

15. Mammalian Kidney inferiorvena cava aorta adrenal gland kidney nephron ureter renal vein& artery epithelialcells bladder urethra

16. Nephron • Functional units of kidney • 1 million nephronsper kidney • Function • filter out urea & other solutes (salt, sugar…) • Blood pressure forces blood into nephron • high pressure flow • Proximal tubule, loop of Henle and distal tubule reabsorb valuable solutes & H2O back into bloodstream

17. Mammalian kidney • Interaction of circulatory & excretory systems • Circulatory system • Glomerulus = ball of capillaries • Excretory system • Bowman’s capsule • Proximal tubule • Loop of Henle • descending limb • ascending limb • Distal tubule • Collecting duct Proximal tubule Distal tubule Bowman’s capsule Glomerulus Glucose H2O Na+ Cl- Amino acids H2O H2O Na+ Cl- H2O Mg++ Ca++ H2O H2O Collecting duct Loop of Henle

18. Osmotic control in nephron • How is all this re-absorption achieved? • tight osmotic control to reduce the energy costof excretion • use diffusioninstead of active transportwherever possible

19. Any Questions?

20. Regulating the InternalEnvironment Maintaining Homeostasis

21. high low Negative Feedback Loop hormone or nerve signal lowersbody condition (return to set point) gland or nervous system sensor specific body condition sensor raisesbody condition(return to set point) gland or nervous system hormone or nerve signal

22. high low Nervous System Control Controlling Body Temperature nerve signals brain sweat dilates surfaceblood vessels body temperature brain constricts surfaceblood vessels shiver nerve signals

23. nephron high low Endocrine System Control Blood Osmolarity ADH increasethirst increasedwaterreabsorption pituitary blood osmolarity blood pressure ADH = AntiDiuretic Hormone

24. Maintaining Water Balance • 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 H2O H2O H2O

25. high low JGA adrenalgland nephron Endocrine System Control Blood Osmolarity JGA = JuxtaGlomerular Apparatus blood osmolarity blood pressure increasedwater & saltreabsorption in kidney rennin aldosterone angiotensigen angiotensin

26. adrenalgland 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 & H2O in kidneys • puts more water & salts back in blood

27. increasethirst pituitary nephron high JuxtaGlomerularApparatus low adrenalgland nephron Endocrine System Control Blood Osmolarity ADH increasedwaterreabsorption blood osmolarity blood pressure increasedwater & saltreabsorption renin aldosterone angiotensinogen angiotensin

28. Don’t get batty… Ask Questions!!