Slide 1Slide 2Slide 3Slide 4chapter 17: energetic costs of meeting environmental challengesSlide 6OutlineSlide 8Slide 9Slide 10Slide 11Slide 12Determinants of Body Heat & TemperatureHc = conduction & convectionHr = solar radiation absorbed by surface of animalHe = evaporation (or condensation)Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25lecture 26 thursday 04 dec. 2003vertebrate physiologyecol 437university of arizonafall 2003instructor: kevin bonine t.a.: bret pasch???kevin boninefull bio: • married with doginterests:• vertebrate physiology• conservation biology• lizards• frisbee• bad jokes• treadmillshappy halloween 2003chapter 17: energetic costs of meeting environmental challengesThe World's Tallest Thermometer in Baker, CA.Outline•Temperature Dependence of Metabolic Rate•Determinants of Body Heat & Temperature•Physiological Classification•Thermal Biology of Ectotherms•Thermal Biology of Endotherms•Neuronal Mechanisms of Temperature ControlIncreased temperature increased rate of chemical reactions increased rate of metabolismQ10 effects: Q10 = MR(t+10) MRtQ10 often = 2 to 3, depends on the two temps used(17-2)Temperature Dependence of Metabolic RatePough et al., 2001snake exampleThermal Acclimation & Recent History of Individual(17-3)Membrane Acclimatization(17-4) -Temperature-Lipid Saturation increases with temp. to decrease fluidity-Cholesterol adds rigidityHeat Shock Proteins-molecular chaperones(17-5)Intertidal adaptationsMarine snailsDeterminants of Body Heat & Temperaturebody heat = heat produced + (heat gained - heat lossed)H total = Hv + Hc + Hr + He + HsHv = metabolic heat productionHc = conduction & convectionHr = radiationHe = evaporationHs = heat storageHc = conduction & convectionconduction - transfer of heat between objects in contact with one another (e.g. group thermoregulation)convection- transfer of heat contained in a mass of gas/liquidby movement of that mass (e.g. wind & water)Hr = solar radiation absorbed by surface of animallocation - shade or sunposture - exposure changescolor - melanin in melanophoresof dermisHe = evaporation (or condensation)vs.Hs = heat storage Evaporative cooling via panting or sweatingLarge animals (small SA : mass)heat up more slowlySpecific Heat ConductanceSurface properties determine-Ectotherms generally with high conductance-Endotherms generally low (feathers, fur, blubber)fur and feathers trap air (low conductance)Regulating Heat TransferBehavioral-posture, location, migrationPhysiological Adjustments-blood flow-piloerection-sweating etc.Acclimatization-fur, fat, metabolic rate, sweatingOntogeny- pigs in different environments (SA / V)(17-8)Physiological Classification (generalized categories)Temperature Stability:-Homeothermy-PoikilothermySource of Heat:-Endothermy-Ectothermy(17-9)-Heterothermy -regional vs. temporalThermal Biology of Ectotherms …in the COLD(17-13)…Ectotherms in the COLD Freeze Tolerance(17-14)- [Solute] leads to osmosisfreezing point-rapid formation of EXTRAcellular ice crystals (nucleation)Ectotherms in the COLDSupercooling/Antifreeze-Supercool by preventing ice crystal formation (supercooled fishes)-Lower Freezing Point Glycerol, Glycoproteins -17C, -47C!Thermal Biology of EndothermsBMR 7-20 X’s greater than ~ sized ectothermmammals: 37-38 ˚Cbirds: 40˚Cpolar bears > 70 ˚C above ambient temperatures!!Thermal Neutral
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