生理學(xué)雙語(yǔ)-代謝系統(tǒng)PPT課件

1,第七章能量代謝與體溫EnergyMetabolismandTemperature,2,第一節(jié)能量代謝EnergyMetabolism,3,新陳代謝是機(jī)體生命活動(dòng)的基本特征，新陳代謝包括物質(zhì)代謝及相伴隨的能量代謝。,4,生物體內(nèi)物質(zhì)代謝過程中所伴隨的能量釋放、轉(zhuǎn)移和利用等，稱為能量代謝。（energymetabolism）。,5,271.1-272.1Thetermmetabolism,meaningliterallychange,isusedtorefertoallthechemicalandenergytransformationsthatoccurinthebody.Theanimalorganismoxidizescarbohydrates,proteins,andfats,producingprincipallyCO2,H2O,andtheenergynecessaryforlifeprocesses.,6,Inthebody,oxidationisnotaone-step,semiexplosivereactionbutacomplex,slow,stepwiseprocesscalledcatabolism分解代謝;異化,whichliberatesenergyinsmall,usableamounts.,7,Energycanbestoredinthebodyintheformofspecialenergyrichphosphatecompoundsandintheformofproteins,fats,andcomplexcarbohydratessynthesizedfromsimplermolecules.Formationofthesesubstancesbyprocessesthattakeup吸收ratherthanliberateenergyiscalledanabolism合成代謝.,8,Theenergyliberatedbycatabolicprocessesinthebodyisusedformaintainingbodyfunctions,digestingandmetabolizingfood,thermoregulation,andphysicalactivity.Itappearsasexternalwork,heat,andenergystorage:Energy=External+Energy+Heatoutputworkstorage,9,Theamountofenergyliberatedperunitoftimeisthemetabolicrate.,10,機(jī)體所需的能量來(lái)源于食物中的糖、脂肪和蛋白質(zhì)。能量的50%以上迅速轉(zhuǎn)化為熱能，用于維持體溫，并向體外散發(fā)。其余則以高能磷酸鍵的形式貯存于體內(nèi)。,11,三磷酸腺苷(ATP)是體內(nèi)能量轉(zhuǎn)化和利用的關(guān)鍵物質(zhì)。磷酸肌酸(CP)是ATP的儲(chǔ)存庫(kù)。,12,EnergyTransferMuchoftheenergyliberatedbycatabolismisnotuseddirectlybycellsbutisappliedinsteadtotheformationofbondsbetweenphosphoricacidresiduesandcertainorganiccompounds.Becausetheenergyofbondformationinsomeofthesephosphatesisparticularlyhigh,relativelylargeamountsofenergy(l0-12kcal/mol)arereleasedwhenthebondishydrolyzed.,13,Compoundscontainingsuchbondsarecalledhigh-energyphosphatecompounds.themostimportanthigh-energyphosphatecompoundisadenosinetriphosphate(ATP).Thisubiquitous無(wú)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、能量代謝測(cè)定的原理和方法測(cè)定在一定時(shí)間內(nèi)機(jī)體所消耗的食物，或者測(cè)定機(jī)體所產(chǎn)生的熱量與所做的外功，都可測(cè)算出整個(gè)機(jī)體的能量代謝率（單位時(shí)間內(nèi)所產(chǎn)生的能量）,17,272.2-273.1Energyisstoredbyformingenergy-richcompounds.Theamountofenergystoragevaries,butinfastingindividualsitiszeroornegative.Therefore,inanadultindividualwhohasnoteatenrecentlyandwhoisnotmoving(orgrowing,reproducing,orlactating泌乳),alloftheenergyoutputappearsasheat.,18,（一）直接測(cè)熱法,19,Calorimetershavebeenconstructedthatcanphysicallyaccommodatehumanbeings.Theheatproducedbytheirbodiesismeasuredbythechangeintemperatureofthewaterinthewallsofthecalorimeter.,20,Thecaloricvaluesofthecommonfoodstuffs,asmeasuredinabombcalorimeter,彈式測(cè)熱計(jì)：測(cè)定食物潛能的儀器，即為一中空的鋼容器(彈)，內(nèi)部充滿純氧，將定量的食物置于其內(nèi)的鉑盤上加以氧化。容器浸在一定量的水中。食物氧化產(chǎn)生的熱被水吸收，即能從水中測(cè)定其熱量arefoundtobe4.1kcal/gofcarbohydrate,9.3kcal/goffat,and4.1kcal/gofprotein.,21,(二）間接測(cè)熱法,22,食物熱價(jià)將1g食物氧化（或在體外燃燒）時(shí)所釋放出來(lái)的能量稱為食物的熱價(jià)（thermalequivalentoffood）。,23,2呼吸商一定時(shí)間內(nèi)機(jī)體的CO2產(chǎn)量與耗氧量的比值稱為呼吸商（respiratoryquotient,RQ）。,24,Therespiratoryquotient(RQ)istheratiointhesteadystateofthevolumeofCO2producedtothevolumeofO2consumedperunitoftime.TheRQofcarbohydrateis1.00,andthatoffatisabout0.70.DeterminingtheRQofproteininthebodyisacomplexprocess,butanaveragevalueof0.82hasbeencalculated.,25,3.食物的氧熱價(jià)某種食物氧化時(shí)消耗1升氧所產(chǎn)生的熱量稱為該種食物的氧熱價(jià)。,26,4.非蛋白呼吸商在一定時(shí)間內(nèi)機(jī)體中糖和脂肪氧化（非蛋白質(zhì)代謝）的CO2產(chǎn)量和耗氧量的比值，即非蛋白呼吸商。,27,28,間接測(cè)熱法計(jì)算主要過程:1.實(shí)驗(yàn)測(cè)得的機(jī)體24小時(shí)內(nèi)的耗氧量和CO2產(chǎn)量以及尿氮量;2.由尿氮量算出被氧化分解的蛋白質(zhì)量。3.由被氧化的蛋白質(zhì)量查表其產(chǎn)熱量、耗氧量和CO2產(chǎn)量；4.其次從總耗氧量和總CO2產(chǎn)量中減去蛋白質(zhì)耗氧量和CO2產(chǎn)量，計(jì)算出非蛋白呼吸商。,29,5.根據(jù)非蛋白呼吸商查表的相應(yīng)的非蛋白呼吸商的氧熱價(jià)，計(jì)算出非蛋白代謝的產(chǎn)熱量；6.最后，24小時(shí)產(chǎn)熱量為蛋白質(zhì)代謝的產(chǎn)熱量與非蛋白代謝的產(chǎn)熱量之和。,30,31,IndirectCalorimetryEnergyproductioncanalsobecalculatedbymeasuringtheproductsoftheenergy-producingbiologicoxidations-ie,CO2,H2O,andtheendproductsofproteincatabolismproduced-orbymeasuringtheO2consumed.Thisisindirectcalorimetry.Itisdifficulttomeasurealloftheendproducts,butmeasurementofO2consumptionisrelativelyeasy.,32,SinceO2isnotstoredandsinceitsconsumption,exceptwhenanO2debtisbeingincurredorrepaid,alwayskeepspacewithimmediateneeds,theamountofO2consumedperunitoftimeisproportionatetotheenergyliberated.,33,二.影響能量代謝的主要因素(一)肌肉活動(dòng)肌肉活動(dòng)對(duì)能量代謝的影響最為顯著。,34,（二)精神活動(dòng)無(wú)意識(shí)的肌緊張某些激素釋放增多,35,(三)食物的特殊動(dòng)力作用食物能使機(jī)體產(chǎn)生“額外”熱量的現(xiàn)象稱為食物的特殊動(dòng)力作用（specificdynamicaction）。,36,（四）環(huán)境溫度安靜時(shí)的能量代謝，在20-30度的環(huán)境中最為穩(wěn)定。,37,273.2-274.3FactorsAffectingtheMetabolicRateThemetabolicrateisaffectedbymanyfactors.Themostimportantismuscularexertion.O2consumptioniselevatednotonlyduringexertionbutalsoforaslongafterwardasisnecessarytorepaytheO2debt.,38,Recentlyingestedfoodsalsoincreasethemetabolicratebecauseoftheirspecificdynamicaction(SDA).TheSDAofafoodistheobligatory強(qiáng)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攝氏degreeofelevation.,42,三、基礎(chǔ)代謝基礎(chǔ)代謝（basalmetabolism）是指基礎(chǔ)狀態(tài)下的能量代謝。,43,基礎(chǔ)代謝率（basalmetabolicrate,BMR）是指在基礎(chǔ)狀態(tài)下，單位時(shí)間內(nèi)的產(chǎn)熱量。基礎(chǔ)狀態(tài)是指人體處在清醒而又非常安靜，靜臥，室溫2025度、食后12-14h）排除精神緊張的影響?；A(chǔ)代謝率通常以kJ/m2h來(lái)表示。,44,45,Themetabolicratedeterminedatrestinaroomatacomfortabletemperatureinthethermoneutral熱平衡的zone12-14hoursafterthelastmealiscalledthestandard,orbasalmetabolicrate(BMR).Thisvaluefallsabout10%duringsleepandupto40%duringprolongedstarvation.,46,Therateintheseconditionsiscalledtheminimalmetabolicrate.Therateduringnormaldaytimeactivitiesis,ofcourse,higherthantheBMRbecauseofmuscularactivityandfoodintakeandissometimescalledthefieldmetabolicrate.ThemaximummetabolicratereachedduringexerciseisoftensaidtobetentimestheBMR,buttrainedathletescanincreasetheirmetabolicrateasmuchas20-fold.,47,Forconvenience,theBMRisusuallyexpressedasapercentincreaseordecreaseaboveorbelowasetofgenerallyusedstandardnormalvalues.Thus,avalueof65meansthattheindividualsBMRis65%abovethestandardforthatageandsex.,48,第二節(jié)體溫及其調(diào)節(jié),49,一、體溫（一）表層體溫和深部體溫人體的外周組織即表層，包括皮膚、皮下組織和肌肉等的溫度稱為表層溫度（shelltemperature）。,50,機(jī)體深部（心、肺、腦和腹腔內(nèi)臟等處）的溫度稱為體核(深部)溫度（coretemperature）。,51,體溫是指機(jī)體深部的平均溫度。,52,臨床上通常用口腔溫度、直腸溫度和腋窩溫度來(lái)代表體溫。,53,直腸36.937.9,口腔36.737.7,腋窩36.037.4,低0.20.3,低0.30.5,54,（二）體溫的正常變動(dòng)在一晝夜之中，人體體溫呈周期性波動(dòng)。清晨2-6時(shí)體溫最低，午后1-6時(shí)最高。波動(dòng)的幅值一般不超過1度。體溫的這種晝夜周期性波動(dòng)稱為晝夜節(jié)律或日周期（circadianrhythm）。,55,女子的基礎(chǔ)體溫隨月經(jīng)周期而發(fā)生變動(dòng)。在排卵后體溫升高，體溫升高一直持續(xù)至下次月經(jīng)開始。,56,57,體溫也與年齡有關(guān)。,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標(biāo)準(zhǔn)foradults.,64,Duringexercise,theheatproducedbymuscularcontractionaccumulatesinthebody,andtherectaltemperaturenormallyrisesashighas40C(104F).Thisriseisdueinparttotheinabilityoftheheatdissipating散熱mechanismstohandlethegreatlyincreasedamountofheatproduced,butthereisevidencethatinadditionthereisanelevationofthebodytemperatureatwhichtheheat-dissipatingmechanismsareactivatedduringexercise.,65,Bodytemperaturealsorisesslightlyduringemotionalexcitement,probablyowingtouncoscioustensingofthemuscles.Itischronicallyelevatedbyasmuchas0.5Cwhenthemetabolicrateishigh,asinhyperthyroidism,andloweredwhenthemetabolicrateislow,asinhypothyroidism.Someapparentlynormaladultschronicalhaveatemperatureabovethenormalrange(constitutionalhyperthermia).,66,二、體熱平衡產(chǎn)熱=散熱體溫維持不變產(chǎn)熱量散熱量，體溫升高產(chǎn)熱量散熱量,體溫下降,67,68,(一）產(chǎn)熱過程,69,70,人在寒冷環(huán)境中主要依靠寒戰(zhàn)來(lái)增加產(chǎn)熱量。寒戰(zhàn)是骨骼肌發(fā)生不隨意的節(jié)律性收縮的表現(xiàn)。寒戰(zhàn)前肌緊張,71,腎上腺素和去甲腎上腺素可使產(chǎn)熱量迅速增加；甲狀腺激素則使產(chǎn)熱緩慢增加。,72,243.3-244.5Avarietyofbasicchemicalreactioncontributetobodyheatproductionatalltimes.Ingestionoffoodincreasesheatproductionbecauseofthespecificdynamicactionofthefood,butthemajorsourceofheatisthecontractionskeletalmuscle.,73,Heatproductioncanvariedbyendocrinemechanismsintheabsencefoodintakeormuscularexertion.Epinephrineandnorepinephrineproducearapidbutshort-livedincreaseinheatproduction;thyroidhormonesproduceaslowlydevelopingbutprolongedincrease.Furthermore,sympatheticdischargeisdecreasedduringfastingandincreasedbyfeeding.,74,Asourceofconsiderableheat,particularlyininfants,isbrownfat.Thisfathashighrateofmetabolism,anditsthermogenicfunctionhasbeenlikenedtothatofanelectricblanket.,75,（二）散熱過程人體的主要散熱部位是皮膚。當(dāng)環(huán)境溫度低于體溫時(shí)，大部分的體熱通過皮膚的輻射、傳導(dǎo)和對(duì)流散熱。一部分熱量通過蒸發(fā)來(lái)散發(fā)。,76,1輻射、傳導(dǎo)和對(duì)流散熱輻射（radiation）散熱這是機(jī)體以熱射線的形式將熱量傳給外界較冷物體的散熱方式。,77,傳導(dǎo)（conduction）散熱：是機(jī)體的熱量直接傳給同它接觸的較冷物體的散熱方式。,78,對(duì)流（convection）散熱是指通過身體周圍氣體散熱的方式。,79,80,體溫調(diào)節(jié)中樞通過神經(jīng)控制著皮膚血流量來(lái)改變皮膚溫度，從而調(diào)節(jié)散熱量。,81,Radiationistransferofheatbyinfraredelectromagneticradiationfromoneobjecttoanotheratadifferenttemperaturewithwhichitisnotincontact.Whenanindividualisinacoldenvironment,heatislostbyconductiontothesurroundingairandbyradiationtocoolobjectsinthevicinity.,82,Conversely,ofcourse,heatistransferredtoanindividualandtheheatloadisincreasedbytheseprocesseswhentheenvironmentaltemperatureisabovebodytemperature.,83,Conductionheatexchangebetweenobjectsorsubstancesatdifferenttemperaturesthatareincontactwithoneother.Abasiccharacteristicofmatteristhatitsmoleculesareinmotion,withtheamountofmotionproportionatetothetemperature.Thesemoleculescollidewiththemoleculesincoolerobjects,transferringthermalenergytothem.Theamountofheattransferredisproportionatetothetemperaturedifferencebetweentheobjectsincontact(thermalgradient).,84,Convection:anobjectcontactwithairatadifferenttemperaturechangesthespecificgravityoftheair,andsincewarmairrisesandcoolairfalls,anewsupplyofairisbroughtintocontactwiththeobject.,85,在炎熱環(huán)境中,交感神經(jīng)緊張度降低,皮膚小動(dòng)脈舒張,動(dòng)靜脈吻合支開放,皮膚血流量激增,皮膚溫度升高,散熱增加。,86,在寒冷環(huán)境中,交感神經(jīng)緊張度升高,皮膚小動(dòng)脈收縮,皮膚血流量銳減,皮膚溫度下降,散熱顯著減少。此時(shí)機(jī)體表層成為隔熱層，減少散熱。,87,2.蒸發(fā)（evaporation）散熱當(dāng)環(huán)境溫度較低時(shí)，大部分的體熱靠輻射、傳導(dǎo)和對(duì)流的方式散熱，小部分體熱由蒸發(fā)散熱；,88,隨著環(huán)境溫度升高時(shí)，蒸發(fā)的散熱作用則增強(qiáng)；當(dāng)環(huán)境溫度等于或與高于體溫時(shí)，蒸發(fā)就成為機(jī)體唯一的散熱方式。,89,人體蒸發(fā)有二種形式：即不感蒸發(fā)和發(fā)汗。,90,人體皮膚和呼吸道都不斷有水分滲出被蒸發(fā)掉，稱為不感蒸發(fā)，其中皮膚蒸發(fā)又稱為不顯汗，與汗腺的活動(dòng)無(wú)關(guān)。室溫下人體24h的不感蒸發(fā)量為500ml。,91,發(fā)汗汗腺分泌汗液的活動(dòng)稱為發(fā)汗。,92,汗液是低滲的。所以當(dāng)機(jī)體因量發(fā)汗，導(dǎo)致高滲性脫水。,93,發(fā)汗是反射活動(dòng)。人體汗腺接受交感膽堿能纖維（交感節(jié)后纖維）支配,(M受體)。主要發(fā)汗中樞在下丘腦。,94,溫?zé)嵝园l(fā)汗精神性發(fā)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、體溫調(diào)節(jié)體溫調(diào)節(jié)機(jī)制通過調(diào)節(jié)產(chǎn)熱過程和散熱過程，維持體溫相對(duì)穩(wěn)定。,100,體溫調(diào)節(jié)自動(dòng)控制示意圖,101,（一）溫度感受器1.外周溫度感受器冷感受器溫覺感受器,102,大鼠陰囊皮膚冷覺和溫覺感受器,103,中樞溫度感受器在視前區(qū)-下丘腦前部（preopticanteriorhypothalamus,PO/AH）熱敏神經(jīng)元冷敏神經(jīng)元,104,下丘腦局部加溫時(shí)熱敏神經(jīng)元放電的記錄,105,由下丘腦視前區(qū)導(dǎo)出的溫度敏感神經(jīng)元的放電活動(dòng),106,107,（二）體溫調(diào)節(jié)中樞調(diào)節(jié)體溫的基本中樞在下丘腦，視前區(qū)-下丘腦前部PO/AH是體溫調(diào)節(jié)的基本部位。,108,109,環(huán)境溫度的信息上傳到體溫調(diào)節(jié)中樞，通過后者的整合作用，形成決策。然后改變產(chǎn)熱和散熱過程,以調(diào)節(jié)體溫。,110,245.1-6Thereflexthermoregulatoryreponsesinhumanincludeautonomic,somatic,endocrine,andbehavioralchanges.Onegroupofresponsesincreasesheatlossanddecreasesheatproduction;theotherdecreasesheatlossandincreasesheatproduction.Ingeneral,exposuretoheatstimulatestheformergroupofresponsesandinhibitsthelatter,whereasexposuretocolddoestheopposite.,111,Table14-5.Temperature-regulatingmechanisms.MechanismsactivatedbycoldIncreaseheatproductionShiveringHungerIncreasedvoluntaryactivityIncreasedsecretionofnorepinephrineandepinephrine,112,DecreaseheatlossCutaneousvasoconstrictionCurlingup蜷縮Horripilation毛