ChapterTwenty-FiveControl ofBodyTemperature& Water BalanceCreated by S.A. Sparace (2021)
S.A. Sparace (2021)Homeostasis–the maintenance of steady normal (optimal) internal conditions of acell or organism by internal control mechanisms in the face of opposing & fluctuatingexternal conditions.Examples include . . .•Blood pH, oxygen& glucose levels.•Accumulation & eliminationof metabolic wastes.•Body temperature.•Cellular/bodily solute& water content.225.1An Animal’s Regulation of Body Temperature HelpsMaintainHomeostasis.Thermoregulation
S.A. Sparace (2021)Thermoregulation– a form of homeostasis bywhich animals maintain an internal temperaturewithin a tolerable range.Two Main Thermoregulation Strategies:Endotherms–“warm-blooded” animals that warmthemselves via heat derived from their own metabolism(e.g. mammals, birds & most vertebrates).Ectotherms–“cold-blooded” animals that warmthemselves by absorbing heat from their surroundings(e.g. fish, amphibians, lizards, snakes, mostinvertebrates).325.1An Animal’s Regulation of Body Temperature HelpsMaintain Homeostasis.
S.A. Sparace (2021)Kleptotherm– one animal shares the metabolic heat of another.Poikilotherm– aka “temperature conformer” or “heterotherms”– organism whose body temperature varies considerably as aresult of variations in the environmental temperature withoutany effort to regulate.4Are there other thermoregulation strategies ?(Alaska Wood Frog)
S.A. Sparace (2021)1.Conduction— the transfer of heat by direct contact.2.Convection— the transfer of heat by movement of air or liquid past a surface.3.Radiation— the absorption or emission of electromagnetic waves.4.Evaporation— the loss of heat from the surface of a liquid that is losing someof its molecules as a gas.5Heat is Gained or Lost in Four Ways.RadiationConvectionEvaporationConductionThermoregulationin the Agama Lizard
S.A. Sparace (2021)1.Metabolic Heat Production– increased ratesof metabolism give off more heat (e.g. vigorousexercise & shivering).2.Insulation– such as hair, feathers, fat.625.2Thermoregulation Involves Adaptations that BalanceHeat Gain and Loss.(“Piloerection”)
S.A. Sparace (2021)1.Metabolic Heat Production– increased ratesof metabolism give off more heat (e.g. vigorousexercise & shivering).2.Insulation– such as hair, feathers, fat.3.Circulatory System Adaptations:•Changes in blood flow to/from skin.•Counter current heat exchange.725.2Thermoregulation Involves Adaptations that BalanceHeat Gain and Loss.353020103327189Warm arterialblood frombody coreRe-warmingvenous bloodreturning tobody coreHeat Flow(Much Heat Loss)(Little Heat Loss)
S.A. Sparace (2021)1.Metabolic Heat Production– increased ratesof metabolism give off more heat (e.g. vigorousexercise & shivering).