1 / 37

Regulating the Internal Environment

Regulating the Internal Environment. Conformers vs. Regulators. Two 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.

jbryant
Download Presentation

Regulating the Internal Environment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Regulating the InternalEnvironment

  2. Conformers vs. Regulators • Two 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 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 Overcoming limitations of diffusion • Evolution of exchange systems for • distributing nutrients • circulatory system • removing wastes • excretory system systems to support multicellular organisms

  7. Osmolarity • the solute concentration of a solution, determines movement of water across a selectively permeable membrane • If two solutions are isoosmotic • movement of water is equal in both directions • If two solutions differ in osmolarity • net flow of water is from hypoosmotic to the hyperosmotic solution

  8. Higher soluteconcentration Lower soluteconcentration • • Lower free H2Oconcentration Higher free H2Oconcentration • • Figure 44.2 Selectively permeablemembrane Solutes Water Hypoosmotic side: Hyperosmotic side: Net water flow

  9. hypotonic Osmoregulation • Water balance • freshwater • Hypotonic/hypoosmotic • water flow into cells & salt loss • saltwater • Hypertonic/hyperosmotic • 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? • always lose water (breathing & waste) • may lose life while searching for water

  10. H O H | | | –C– C–OH N | H R Animalspoison themselvesfrom the insideby digestingproteins! 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

  11. 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) aquatic terrestrial terrestrial egg layer

  12. 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 water • need to protectembryo in egg • uric acid • least toxic

  13. 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

  14. 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 Ureacosts energyto synthesize,but it’s worth it! mammals

  15. 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!

  16. O O O N N N N H H H H And that folks, is why mostmale birds don’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 still excrete N waste as white paste • no liquid waste • uric acid = white bird “poop”!

  17. 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 • excretion • expel concentrated urine (N waste + solutes + toxins) from body concentratedurine

  18. Figure 44.14e 200 m Blood vessels from a human kidney. Arterioles and peritubular capillaries appear pink; glomeruli appear yellow.

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

  20. 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 • proximal tubule • 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

  21. Transport epithelium 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 (filter) H2O & solutes out of blood vessel BIG problems when you start out with high blood pressure in systemhypertension = kidney damage

  22. Distal tubule Proximal tubule Figure 44.15 NaCl Nutrients H2O H2O HCO3 K HCO3 NaCl H NH3 H K Filtrate CORTEX Loop ofHenle NaCl H2O OUTERMEDULLA NaCl Collectingduct Key Urea Active transport NaCl H2O Passive transport INNERMEDULLA

  23. Osmolarityof interstitialfluid(mOsm/L) Figure 44.16-1 300 300 300 300 H2O CORTEX 400 400 H2O H2O H2O OUTERMEDULLA 600 600 H2O H2O 900 900 Key H2O INNERMEDULLA Activetransport 1,200 1,200 Passivetransport

  24. Osmolarityof interstitialfluid(mOsm/L) Figure 44.16-2 300 300 100 300 100 300 NaCl H2O CORTEX 400 200 400 H2O NaCl H2O NaCl NaCl H2O OUTERMEDULLA 600 600 400 NaCl H2O H2O NaCl 900 700 900 Key H2O NaCl INNERMEDULLA Activetransport 1,200 1,200 Passivetransport

  25. Osmolarityof interstitialfluid(mOsm/L) Figure 44.16-3 300 300 100 300 100 300 300 H2O NaCl H2O CORTEX 400 200 400 400 H2O NaCl H2O NaCl H2O H2O NaCl NaCl NaCl H2O H2O OUTERMEDULLA 600 600 600 400 H2O NaCl H2O Urea H2O H2O NaCl 900 700 900 Urea Key H2O NaCl H2O INNERMEDULLA Urea Activetransport 1,200 1,200 1,200 Passivetransport

  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 • cells u proteins • remain in blood (too big) • Reabsorbed: active transport • Na+u amino acids • Cl–u glucose • Reabsorbed: diffusion • Na+u Cl– • H2O • Excreted • urea • excess H2O u excess solutes (glucose, salts) • toxins, drugs, “unknowns”

  28. Regulating the InternalEnvironment Maintaining Homeostasis

  29. 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

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

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

  32. 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 • antidiuretic 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

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

  34. 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?

  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. ADHreceptor LUMEN Collectingduct Figure 44.20 COLLECTINGDUCT CELL ADH cAMP Second-messengersignaling molecule Storagevesicle Exocytosis Aquaporinwater channel H2O H2O

More Related