生理学双语-代谢系统PPT课件

1,第七章能量代谢与体温EnergyMetabolismandTemperature,2,第一节能量代谢EnergyMetabolism,3,新陈代谢是机体生命活动的基本特征，新陈代谢包括物质代谢及相伴随的能量代谢。,4,生物体内物质代谢过程中所伴随的能量释放、转移和利用等，称为能量代谢。（energymetabolism）。,5,271.1-272.1Thetermmetabolism,meaningliterallychange,isusedtorefertoallthechemicalandenergytransformationsthatoccurinthebody.Theanimalorganismoxidizescarbohydrates,proteins,andfats,producingprincipallyCO2,H2O,andtheenergynecessaryforlifeprocesses.,6,Inthebody,oxidationisnotaone-step,semiexplosivereactionbutacomplex,slow,stepwiseprocesscalledcatabolism分解代谢;异化,whichliberatesenergyinsmall,usableamounts.,7,Energycanbestoredinthebodyintheformofspecialenergyrichphosphatecompoundsandintheformofproteins,fats,andcomplexcarbohydratessynthesizedfromsimplermolecules.Formationofthesesubstancesbyprocessesthattakeup吸收ratherthanliberateenergyiscalledanabolism合成代谢.,8,Theenergyliberatedbycatabolicprocessesinthebodyisusedformaintainingbodyfunctions,digestingandmetabolizingfood,thermoregulation,andphysicalactivity.Itappearsasexternalwork,heat,andenergystorage:Energy=External+Energy+Heatoutputworkstorage,9,Theamountofenergyliberatedperunitoftimeisthemetabolicrate.,10,机体所需的能量来源于食物中的糖、脂肪和蛋白质。能量的50%以上迅速转化为热能，用于维持体温，并向体外散发。其余则以高能磷酸键的形式贮存于体内。,11,三磷酸腺苷(ATP)是体内能量转化和利用的关键物质。磷酸肌酸(CP)是ATP的储存库。,12,EnergyTransferMuchoftheenergyliberatedbycatabolismisnotuseddirectlybycellsbutisappliedinsteadtotheformationofbondsbetweenphosphoricacidresiduesandcertainorganiccompounds.Becausetheenergyofbondformationinsomeofthesephosphatesisparticularlyhigh,relativelylargeamountsofenergy(l0-12kcal/mol)arereleasedwhenthebondishydrolyzed.,13,Compoundscontainingsuchbondsarecalledhigh-energyphosphatecompounds.themostimportanthigh-energyphosphatecompoundisadenosinetriphosphate(ATP).Thisubiquitous无所不在的moleculeistheenergystorehouseofthebody.,14,Uponhydrolysistoadenosinediphosphate(ADP),ATPliberatesenergydirectlytosuchprocessesasmusclecontraction,activetransport,andthesynthesisofmanychemicalcompounds.,15,CaloriesThestandardunitofheatenergyisthecalorie(cal),definedastheamountofheatenergynecessarytoraisethetemperatureof1gofwater1degree,from15Cto16C.Thisunitisalsocalledthegramcalorie,smallcalorie,orstandardcalorie.TheunitcommonlyusedinphysiologyandmedicineistheCalorie(kilocalorie,kcal),whichequals1000cal.,16,一、能量代谢测定的原理和方法测定在一定时间内机体所消耗的食物，或者测定机体所产生的热量与所做的外功，都可测算出整个机体的能量代谢率（单位时间内所产生的能量）,17,272.2-273.1Energyisstoredbyformingenergy-richcompounds.Theamountofenergystoragevaries,butinfastingindividualsitiszeroornegative.Therefore,inanadultindividualwhohasnoteatenrecentlyandwhoisnotmoving(orgrowing,reproducing,orlactating泌乳),alloftheenergyoutputappearsasheat.,18,（一）直接测热法,19,Calorimetershavebeenconstructedthatcanphysicallyaccommodatehumanbeings.Theheatproducedbytheirbodiesismeasuredbythechangeintemperatureofthewaterinthewallsofthecalorimeter.,20,Thecaloricvaluesofthecommonfoodstuffs,asmeasuredinabombcalorimeter,弹式测热计：测定食物潜能的仪器，即为一中空的钢容器(弹)，内部充满纯氧，将定量的食物置于其内的铂盘上加以氧化。容器浸在一定量的水中。食物氧化产生的热被水吸收，即能从水中测定其热量arefoundtobe4.1kcal/gofcarbohydrate,9.3kcal/goffat,and4.1kcal/gofprotein.,21,(二）间接测热法,22,食物热价将1g食物氧化（或在体外燃烧）时所释放出来的能量称为食物的热价（thermalequivalentoffood）。,23,2呼吸商一定时间内机体的CO2产量与耗氧量的比值称为呼吸商（respiratoryquotient,RQ）。,24,Therespiratoryquotient(RQ)istheratiointhesteadystateofthevolumeofCO2producedtothevolumeofO2consumedperunitoftime.TheRQofcarbohydrateis1.00,andthatoffatisabout0.70.DeterminingtheRQofproteininthebodyisacomplexprocess,butanaveragevalueof0.82hasbeencalculated.,25,3.食物的氧热价某种食物氧化时消耗1升氧所产生的热量称为该种食物的氧热价。,26,4.非蛋白呼吸商在一定时间内机体中糖和脂肪氧化（非蛋白质代谢）的CO2产量和耗氧量的比值，即非蛋白呼吸商。,27,28,间接测热法计算主要过程:1.实验测得的机体24小时内的耗氧量和CO2产量以及尿氮量;2.由尿氮量算出被氧化分解的蛋白质量。3.由被氧化的蛋白质量查表其产热量、耗氧量和CO2产量；4.其次从总耗氧量和总CO2产量中减去蛋白质耗氧量和CO2产量，计算出非蛋白呼吸商。,29,5.根据非蛋白呼吸商查表的相应的非蛋白呼吸商的氧热价，计算出非蛋白代谢的产热量；6.最后，24小时产热量为蛋白质代谢的产热量与非蛋白代谢的产热量之和。,30,31,IndirectCalorimetryEnergyproductioncanalsobecalculatedbymeasuringtheproductsoftheenergy-producingbiologicoxidations-ie,CO2,H2O,andtheendproductsofproteincatabolismproduced-orbymeasuringtheO2consumed.Thisisindirectcalorimetry.Itisdifficulttomeasurealloftheendproducts,butmeasurementofO2consumptionisrelativelyeasy.,32,SinceO2isnotstoredandsinceitsconsumption,exceptwhenanO2debtisbeingincurredorrepaid,alwayskeepspacewithimmediateneeds,theamountofO2consumedperunitoftimeisproportionatetotheenergyliberated.,33,二.影响能量代谢的主要因素(一)肌肉活动肌肉活动对能量代谢的影响最为显著。,34,（二)精神活动无意识的肌紧张某些激素释放增多,35,(三)食物的特殊动力作用食物能使机体产生“额外”热量的现象称为食物的特殊动力作用（specificdynamicaction）。,36,（四）环境温度安静时的能量代谢，在20-30度的环境中最为稳定。,37,273.2-274.3FactorsAffectingtheMetabolicRateThemetabolicrateisaffectedbymanyfactors.Themostimportantismuscularexertion.O2consumptioniselevatednotonlyduringexertionbutalsoforaslongafterwardasisnecessarytorepaytheO2debt.,38,Recentlyingestedfoodsalsoincreasethemetabolicratebecauseoftheirspecificdynamicaction(SDA).TheSDAofafoodistheobligatory强制性的energyexpenditurethatoccursduringitsassimilation同化intothebody.Anamountofproteinsufficienttoprovide100kcalincreasesthemetabolicrateatotalof30kcal;asimilaramountofcarbohydrateincreasesit6kcal;andasimilaramountoffat,4kcal.,39,Thismeans,ofcourse,thatthecaloriesavailablefromthethreefoodsareineffectreducedbythisamount;theenergyusedintheirassimilationmustcomefromthefooditselforfromthebodyenergystores.ThecauseoftheSDA,whichmaylastupto6hours,isuncertain.,40,Anotherfactorthatstimulatesmetabolismistheenvironmentaltemperature.Thecurve.relatingthemetabolicratetotheenvironmentaltemperatureisU-shaped.Whentheenvironmentaltemperatureislowerthanbodytemperature,heat-conservingmechanismssuchasshiveringareactivatedandthemetabolicraterises.,41,Whenthetemperatureishighenoughtoraisethebodytemperature,thereisageneralaccelerationofmetabolicprocesses,andthemetabolicraterisesabout14%foreachCelsius摄氏degreeofelevation.,42,三、基础代谢基础代谢（basalmetabolism）是指基础状态下的能量代谢。,43,基础代谢率（basalmetabolicrate,BMR）是指在基础状态下，单位时间内的产热量。基础状态是指人体处在清醒而又非常安静，静卧，室温2025度、食后12-14h）排除精神紧张的影响。基础代谢率通常以kJ/m2h来表示。,44,45,Themetabolicratedeterminedatrestinaroomatacomfortabletemperatureinthethermoneutral热平衡的zone12-14hoursafterthelastmealiscalledthestandard,orbasalmetabolicrate(BMR).Thisvaluefallsabout10%duringsleepandupto40%duringprolongedstarvation.,46,Therateintheseconditionsiscalledtheminimalmetabolicrate.Therateduringnormaldaytimeactivitiesis,ofcourse,higherthantheBMRbecauseofmuscularactivityandfoodintakeandissometimescalledthefieldmetabolicrate.ThemaximummetabolicratereachedduringexerciseisoftensaidtobetentimestheBMR,buttrainedathletescanincreasetheirmetabolicrateasmuchas20-fold.,47,Forconvenience,theBMRisusuallyexpressedasapercentincreaseordecreaseaboveorbelowasetofgenerallyusedstandardnormalvalues.Thus,avalueof65meansthattheindividualsBMRis65%abovethestandardforthatageandsex.,48,第二节体温及其调节,49,一、体温（一）表层体温和深部体温人体的外周组织即表层，包括皮肤、皮下组织和肌肉等的温度称为表层温度（shelltemperature）。,50,机体深部（心、肺、脑和腹腔内脏等处）的温度称为体核(深部)温度（coretemperature）。,51,体温是指机体深部的平均温度。,52,临床上通常用口腔温度、直肠温度和腋窝温度来代表体温。,53,直肠36.937.9,口腔36.737.7,腋窝36.037.4,低0.20.3,低0.30.5,54,（二）体温的正常变动在一昼夜之中，人体体温呈周期性波动。清晨2-6时体温最低，午后1-6时最高。波动的幅值一般不超过1度。体温的这种昼夜周期性波动称为昼夜节律或日周期（circadianrhythm）。,55,女子的基础体温随月经周期而发生变动。在排卵后体温升高，体温升高一直持续至下次月经开始。,56,57,体温也与年龄有关。,58,242.3-243.2Inhomeothermicanimals,theactualtemperatureatwhichthebodyismaintainedvariesfromspeciestospeciesand,toalesserdegree,fromindividualtoindividual.Inhumans,thetraditionalnormalvaluefortheoraltemperatureis37C,59,butinonelargeseriesofnormalyoungadults,themorningoraltemperatureaveraged36.7C,withastandarddeviationof0.2C.Therefore,95%ofallyoungadultswouldbeexpectedtohaveamorningoraltemperatureof36.3-37.1C.,60,Variouspartsofthebodyareatdifferenttemperatures,andthemagnitudeofthetemperaturedifferencebetweenthepartsvarieswiththeenvironmentaltemperature.Theextremitiesaregenerallycoolerthantherestofthebody,61,Therectaltemperatureisrepresentativeofthetemperatureatthecoreofthebodyandvariesleastwithchangesinenvironmentaltemperature.Theoraltemperatureisnormally0.5Clowerthantherectaltemperature,butitisaffectedbymanyfactors,includingingestionofhotorcoldfluids,gum-chewing,smoking,andmouthbreathing.,62,Thenormalhumancoretemperatureundergoesaregularcircadianfluctuationof0.5-0.7C.Inindividualswhosleepatnightandareawakeduringtheday(evenwhenhospitalizedatbedrest),itislowestatabout6amandhighestintheevenings.Itislowestduringsleep,isslightlyhigherintheawakebutrelaxedstate,andriseswithactivity.,63,Inwomen,thereisanadditionalmonthlycycleoftemperaturevariationcharacterizedbyariseinbasaltemperatureatthetimeofovulation.Temperatureregulationislesspreciseinyoungchildren,andtheymaynormallyhaveatemperaturethatis0.5Corsoabovetheestablishednorm标准foradults.,64,Duringexercise,theheatproducedbymuscularcontractionaccumulatesinthebody,andtherectaltemperaturenormallyrisesashighas40C(104F).Thisriseisdueinparttotheinabilityoftheheatdissipating散热mechanismstohandlethegreatlyincreasedamountofheatproduced,butthereisevidencethatinadditionthereisanelevationofthebodytemperatureatwhichtheheat-dissipatingmechanismsareactivatedduringexercise.,65,Bodytemperaturealsorisesslightlyduringemotionalexcitement,probablyowingtouncoscioustensingofthemuscles.Itischronicallyelevatedbyasmuchas0.5Cwhenthemetabolicrateishigh,asinhyperthyroidism,andloweredwhenthemetabolicrateislow,asinhypothyroidism.Someapparentlynormaladultschronicalhaveatemperatureabovethenormalrange(constitutionalhyperthermia).,66,二、体热平衡产热=散热体温维持不变产热量散热量，体温升高产热量散热量,体温下降,67,68,(一）产热过程,69,70,人在寒冷环境中主要依靠寒战来增加产热量。寒战是骨骼肌发生不随意的节律性收缩的表现。寒战前肌紧张,71,肾上腺素和去甲肾上腺素可使产热量迅速增加；甲状腺激素则使产热缓慢增加。,72,243.3-244.5Avarietyofbasicchemicalreactioncontributetobodyheatproductionatalltimes.Ingestionoffoodincreasesheatproductionbecauseofthespecificdynamicactionofthefood,butthemajorsourceofheatisthecontractionskeletalmuscle.,73,Heatproductioncanvariedbyendocrinemechanismsintheabsencefoodintakeormuscularexertion.Epinephrineandnorepinephrineproducearapidbutshort-livedincreaseinheatproduction;thyroidhormonesproduceaslowlydevelopingbutprolongedincrease.Furthermore,sympatheticdischargeisdecreasedduringfastingandincreasedbyfeeding.,74,Asourceofconsiderableheat,particularlyininfants,isbrownfat.Thisfathashighrateofmetabolism,anditsthermogenicfunctionhasbeenlikenedtothatofanelectricblanket.,75,（二）散热过程人体的主要散热部位是皮肤。当环境温度低于体温时，大部分的体热通过皮肤的辐射、传导和对流散热。一部分热量通过蒸发来散发。,76,1辐射、传导和对流散热辐射（radiation）散热这是机体以热射线的形式将热量传给外界较冷物体的散热方式。,77,传导（conduction）散热：是机体的热量直接传给同它接触的较冷物体的散热方式。,78,对流（convection）散热是指通过身体周围气体散热的方式。,79,80,体温调节中枢通过神经控制着皮肤血流量来改变皮肤温度，从而调节散热量。,81,Radiationistransferofheatbyinfraredelectromagneticradiationfromoneobjecttoanotheratadifferenttemperaturewithwhichitisnotincontact.Whenanindividualisinacoldenvironment,heatislostbyconductiontothesurroundingairandbyradiationtocoolobjectsinthevicinity.,82,Conversely,ofcourse,heatistransferredtoanindividualandtheheatloadisincreasedbytheseprocesseswhentheenvironmentaltemperatureisabovebodytemperature.,83,Conductionheatexchangebetweenobjectsorsubstancesatdifferenttemperaturesthatareincontactwithoneother.Abasiccharacteristicofmatteristhatitsmoleculesareinmotion,withtheamountofmotionproportionatetothetemperature.Thesemoleculescollidewiththemoleculesincoolerobjects,transferringthermalenergytothem.Theamountofheattransferredisproportionatetothetemperaturedifferencebetweentheobjectsincontact(thermalgradient).,84,Convection:anobjectcontactwithairatadifferenttemperaturechangesthespecificgravityoftheair,andsincewarmairrisesandcoolairfalls,anewsupplyofairisbroughtintocontactwiththeobject.,85,在炎热环境中,交感神经紧张度降低,皮肤小动脉舒张,动静脉吻合支开放,皮肤血流量激增,皮肤温度升高,散热增加。,86,在寒冷环境中,交感神经紧张度升高,皮肤小动脉收缩,皮肤血流量锐减,皮肤温度下降,散热显著减少。此时机体表层成为隔热层，减少散热。,87,2.蒸发（evaporation）散热当环境温度较低时，大部分的体热靠辐射、传导和对流的方式散热，小部分体热由蒸发散热；,88,随着环境温度升高时，蒸发的散热作用则增强；当环境温度等于或与高于体温时，蒸发就成为机体唯一的散热方式。,89,人体蒸发有二种形式：即不感蒸发和发汗。,90,人体皮肤和呼吸道都不断有水分渗出被蒸发掉，称为不感蒸发，其中皮肤蒸发又称为不显汗，与汗腺的活动无关。室温下人体24h的不感蒸发量为500ml。,91,发汗汗腺分泌汗液的活动称为发汗。,92,汗液是低渗的。所以当机体因量发汗，导致高渗性脱水。,93,发汗是反射活动。人体汗腺接受交感胆碱能纤维（交感节后纤维）支配,(M受体)。主要发汗中枢在下丘脑。,94,温热性发汗精神性发汗,95,Theothermajorprocesstransferringheatfromthebodyinhumansandotheranimalsthatsweatisvaporizationofwaterontheskinandmucousmembranesofthemouthandrespiratorypassages.Vaporizationof1gofwaterremovesabout0.6kcalofheat.,96,Acertainamountofwaterisvaporizedatalltimes.Thisinsensiblewaterlossamountsto50ml/hinhumans.Whensweatsecretionisincreased,thedegreetowhichthesweatvaporizesdependsuponthehumidityoftheenvironment.,97,Itiscommonknowledgethatonefeelshotteronahumidday.Thisisdueinparttothedecreasedvaporizationofsweat,butevenunderconditionsinwhichvaporizationofsweatiscomplete,anindividualinahumidenvironmentfeelswarmerthananindividualinadryenvironment.,98,Duringmuscularexertioninahotenvironment,sweatsecretionreachesvaluesashighas1600ml/h,andinadryatmosphere,mostofthissweatisvaporized.Heatlossbyvaporizationofwaterthereforevariesfrom30toover900kcal/h.,99,三、体温调节体温调节机制通过调节产热过程和散热过程，维持体温相对稳定。,100,体温调节自动控制示意图,101,（一）温度感受器1.外周温度感受器冷感受器温觉感受器,102,大鼠阴囊皮肤冷觉和温觉感受器,103,中枢温度感受器在视前区-下丘脑前部（preopticanteriorhypothalamus,PO/AH）热敏神经元冷敏神经元,104,下丘脑局部加温时热敏神经元放电的记录,105,由下丘脑视前区导出的温度敏感神经元的放电活动,106,107,（二）体温调节中枢调节体温的基本中枢在下丘脑，视前区-下丘脑前部PO/AH是体温调节的基本部位。,108,109,环境温度的信息上传到体温调节中枢，通过后者的整合作用，形成决策。然后改变产热和散热过程,以调节体温。,110,245.1-6Thereflexthermoregulatoryreponsesinhumanincludeautonomic,somatic,endocrine,andbehavioralchanges.Onegroupofresponsesincreasesheatlossanddecreasesheatproduction;theotherdecreasesheatlossandincreasesheatproduction.Ingeneral,exposuretoheatstimulatestheformergroupofresponsesandinhibitsthelatter,whereasexposuretocolddoestheopposite.,111,Table14-5.Temperature-regulatingmechanisms.MechanismsactivatedbycoldIncreaseheatproductionShiveringHungerIncreasedvoluntaryactivityIncreasedsecretionofnorepinephrineandepinephrine,112,DecreaseheatlossCutaneousvasoconstrictionCurlingup蜷缩Horripilation毛