Salmon - salt to fresh waterand backBar-headed goose: can flyover Mt. Everest!Electric eel: stunning its preywith electricityEach animal has uniqueadaptations• Salmon - salt and water balance• Bar-headed geese - gas exchange andcirculatory systems• Electric eel - modified musclesLE 40-2TunaSharkPenguinDolphinSealVolvoxLE 40-5_1EPITHELIAL TISSUEStratifiedcolumnarepitheliumSimplecolumnarepitheliumPseudostratifiedciliated columnarepitheliumColumnar epithelia, which have cells with relatively large cytoplasmic volumes, are oftenlocated where secretion or active absorption of substances is an important function.StratifiedsquamousepitheliaSimple squamousepitheliaCuboidalepitheliaBasement membrane40 µmLE 40-5_2CONNECTIVE TISSUECollagenousfiberElasticfiber120 µm100 µmChondrocytesChondroitinsulfateCartilage150 µmAdipose tissueFat dropletsBloodRed blood cellsWhite blood cell55 µmPlasmaBoneCentralcanal700 µmOsteon30 µmFibrousconnective tissueNucleiLooseconnectivetissueLE 40-5_3MUSCLE TISSUEMultiplenuclei100 µmSkeletal muscleCardiac muscleSmooth muscleNeuronMuscle fiberSarcomereIntercalateddiskNucleus50 µmNucleus25 µmMusclefibersProcessNucleus50 µmCell bodyNERVOUS TISSUELE 40-6Lumen ofstomachMucosa: an epitheliallayer that lines thelumenSubmucosa: a matrix ofconnective tissue thatcontains blood vesselsand nervesMuscularis: consistsmainly of smooth muscletissueSerosa: a thin layer ofconnective and epithelialtissue external to the muscularis0.2 mmLE 40-11ResponseNo heatproducedRoomtemperaturedecreasesRoomtemperatureincreasesSet pointToohotSet pointHeaterturnedoffToocoldSet pointControl center:thermostatHeaterturnedonResponseHeatproduced• An animal’s metabolic rate is closelyrelated to its bioenergetic strategy• Birds and mammals are mainlyendothermic: Their bodies are warmedmostly by heat generated bymetabolism• Endotherms typically have highermetabolic ratesBioenergetic Strategies• Amphibians and reptiles other thanbirds are ectothermic: They gain theirheat mostly from external sources• Ectotherms generally have lowermetabolic rates• Metabolic rates are affected by manyfactors besides whether an animal is anendotherm or ectotherm• Two of these factors are size andactivityInfluences on Metabolic RateSize and Metabolic Rate• Metabolic rate per gram is inverselyrelated to body size among similaranimals• Researchers continue to search for thecauses of this relationship• Different species use energy and materials infood in different ways, depending on theirenvironment• Use of energy is partitioned to BMR (orSMR), activity, homeostasis, growth, andreproductionEnergy BudgetsLE 40-10800,000Endotherms340,000Annual energy expenditure (kcal/yr)Basal(standard)metabolismReproductionTemperatureregulationGrowthActivity60-kg female humanfrom temperate climate4-kg male Adélie penguinfrom Antarctica (brooding)4,0000.025-kg female deer mousefrom temperateNorth America4-kg female pythonfrom Australia8,000EctothermTotal annual energy expenditures. The slices of the pie charts indicate energy expenditures for various functions.Energy expenditures per unit mass (kcal/kg•day). Comparing the daily energy expendituresper kg of body weight for the four animals reinforces two important concepts ofbioenergetics. First, a small animal, such as a mouse, has a much greater energy demandper kg than does a large animal of the same taxonomic class, such as a human (bothmammals). Second, note again that an ectotherm, such as a python, requires much lessenergy per kg than does an endotherm of equivalent size, such as a penguin.Energy expenditure per unit mass(kcal/kg•day)43823336.55.5PythonHumanDeer mouseAdélie penguin• Ectotherms include most invertebrates, fishes,amphibians, and non-bird reptiles• Endotherms include birds and mammals• In general, ectotherms tolerate greater variation ininternal temperature than endothermsEctotherms and EndothermsLE 40-12River otter (endotherm)Largemouth bass (ectotherm)Ambient (environmental) temperature (°C)0 10 20304040Body temperature (°C)302010• Endothermy is more energeticallyexpensive than ectothermy• It buffers the animal’s internaltemperatures against externalfluctuations• It also enables the animal to maintain ahigh level of aerobic metabolismModes of Heat Exchange• Organisms exchange heat by fourphysical processes: conduction,convection, radiation, and evaporationLE 40-13RadiationEvaporationConductionConvectionBalancing Heat Loss and Gain• In thermoregulation, physiological andbehavioral adjustments balance heat lossand gain• Five general adaptations help animalsthermoregulate:– Insulation– Circulatory adaptations– Cooling by evaporative heat loss– Behavioral responses– Adjusting metabolic heat productionInsulation• Insulation is a major thermoregulatoryadaptation in mammals and birds• It reduces heat flow between an animal andits environment• Examples are skin, feathers, fur, andblubber• In mammals, the integumentary system actsas insulating materialLE 40-14EpidermisDermisHypodermisAdipose tissueBlood vesselsHairSweatporeSweatglandMuscleNerveOil glandHair
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