Regulating the Internal Environment

1. Regulating the InternalEnvironment

2. Conformers vs. Regulators • 2 evolutionary paths for organisms • regulate internal environment • maintain relatively constant internal conditions • conformto external environment • 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. Regulating the InternalEnvironment Water Balance & Nitrogenous Waste Removal

5. 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!

6. 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 Solving exchange problem • Evolve of exchange systems for • distributing nutrients • circulatory system • removing wastes • excretory system overcoming the limitations of diffusion

7. Osmoregulation • 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 Why do all land animals have to conserve water? • always lose water (breathing & waste) • may lose life while searching for water

8. H O | | | H –C– C–OH N | H R Animalspoison themselvesfrom the insideby digestingproteins! 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  CO2 +H2O  CO2 +H2O  CO2 +H2O + N  CO2 +H2O + P + N cellular digestion…cellular waste CO2 + H2O NH2= ammonia

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)

10. Nitrogen waste • Aquatic organisms • can afford to lose water • ammonia • most toxic • Terrestrial • need to conserve water • urea • less toxic • Terrestrial egglayers • need to conserve most water • uric acid • least toxic

11. 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

12. 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 H2O • excrete waste • urine = urea, salts, excess sugar & H2O • urine is very concentrated • concentrated NH3 would be too toxic

13. C O H H N N H H Urea • Larger molecule = less soluble • 2NH2 + CO2 = urea • combined in liver • Requires energy to produce • worth the investment of energy • Filtered out by kidneys • collected from cells by circulatory system

14. 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 bittyliving space!

15. O O O N N N N H H H H And that folks, is why a male birddoesn’t have a penis! 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”!

16. Mammalian System blood filtrate • 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 urine

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

18. Nephron • Functional units of kidney • 1 million nephronsper kidney • Function • filter out urea & other solutes (salt, sugar…) • Process • blood plasma filteredinto nephron • selective reabsorption ofvaluable solutes & H2O • greater flexibility & control whyselective reabsorption& not selectivefiltration? “counter current exchange system”

19. How candifferent sectionsallow the diffusionof different molecules? Mammalian kidney • 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 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

20. Nephron: Filtration • At glomerulus • filtered out of blood • H2O • glucose • salts / ions • urea • not filtered out • cells • proteins high blood pressure in kidneysforce to push H2O & solutes out of blood vessel BIG problems when you start out with high blood pressure in systemhypertension = kidney damage

21. Descendinglimb Ascendinglimb Nephron: Re-absorption • Proximal tubule • reabsorbed • NaCl • active transport Na+ • Cl- follows by diffusion • H2O • glucose • HCO3- • bicarbonate • buffer for blood pH

22. Descendinglimb Ascendinglimb Nephron: Re-absorption structure fitsfunction! • Loop of Henle • descending limb • high permeability to H2O • many aquaporins in cell membranes • low permeability to salt • reabsorbed • H2O

23. Descendinglimb Ascendinglimb Nephron: Re-absorption structure fitsfunction! • Loop of Henle • ascending limb • low permeability to H2O • Cl- pump • Na+ follows by diffusion • different membrane proteins • reabsorbed • salts • maintains osmotic gradient

24. Nephron: Re-absorption • Distal tubule • reabsorbed • salts • H2O • HCO3- • bicarbonate

25. Descendinglimb Ascendinglimb Nephron: Reabsorption & Excretion • Collecting duct • reabsorbed • H2O • excretion • urea passed through to bladder

26. 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 the value of acounter current exchange system

27. whyselective reabsorption& not selectivefiltration? 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 • Excreted • urea (highly concentrated) • excess H2O u excess solutes (glucose, salts) • toxins, drugs, “unknowns”

28. Any Questions?

29. Regulating the InternalEnvironment Regulation of Homeostasis

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

31. high low Negative Feedback Model hormone 1 lowersbody condition (return to set point) gland sensor specific body condition sensor raisesbody condition(return to set point) gland hormone 2

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

33. increasethirst pituitary nephron high low Endocrine System Control Blood Osmolarity ADH increasedwaterreabsorption blood osmolarity blood pressure

34. Maintaining Water Balance Get morewater intoblood fast • 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 H2O H2O Alcohol suppresses ADH… makes youurinate a lot! H2O

35. 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

36. Maintaining Water Balance Oooooh,zymogen! • Low blood osmolarity level or low blood pressure Low solutes renin (from JGA) activates angiotensinogen angiotensin triggers aldosterone aldosterone increases absorption of NaCl & H2O in kidney

37. adrenalgland Maintaining Water Balance Get morewater & salt intoblood fast! • 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 Why such arapid responsesystem? Spring a leak?

38. Don’t get batty… Ask Questions!!

39. Homeostasis • Osmoregulation • solute balance & gain or loss of water • Excretion • elimination of nitrogenous wastes • Thermoregulation • maintain temperature within tolerable range

40. Maintaining Water Balance • Monitor blood osmolarity • amount of dissolved material in blood High solutes in brain ADH = anti-diuretic hormone