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UNIT11.AlthoughtheDNAinthenucleusofeachcellcontainsallofthegeneticinformationforallhumantraits,onlyasmallnumberofgenesareactuallyactiveinaparticularcell.Theseactivegenesarethecodesfortheproteinsnecessaryforthespecificcelltype.尽管每一个细胞核中的DNA都包含有人类特性的所有遗传信息，但实际上只有小数基因在特定细胞中有活性，这些活性基因是特有的细胞类型所必须的蛋白密码。2.Infacilitateddiffusion,moleculesmovethroughamembranefromanareaofgreaterconcentrationtoanareaoflesserconcentration,buttheyneedsomehelptodothis.在易化扩散中，大分子经一层膜从高浓度区域向低浓度区域移动，但分子要完成这一工作需要某些帮助。3.Thecellmembraneisselectivelypermeable,thatis,certainsubstancesarepermittedtopassthroughandothersarenot.细胞膜的渗透性是有选择性的，即某些物质允许通过，而其它物质则不行。4.Filtrationmeansthatwateranddissolvedmaterialsareforcedthroughamembranefromanareaofhigherpressuretoanareaoflowerpressure.过滤是指水和已溶解物质经一层膜从高压区压送到低压区。5.ActivetransportrequirestheenergyofATPtomovemoleculesfromanareaoflesserconcentrationtoanareaofgreaterconcentration.主动转运需要ATP这种能使分子从低浓度区向高浓度区移动。1.体内平衡取决于所有不同类型的细胞正常的发挥其功能。(dependupon)Homeostasisdependsuponthenormalfunctionsofallofthedifferentkindsofcells.2.就人口和地域而言，这两个国家差异很大。(withrespectto)Withrespecttopopulationandgeographicalarea,thesetwocountriesvarygreatly.3.染色体由脱氧核糖核酸和蛋白构成，而脱氧核糖核酸又是细胞特征和活性的遗传密码。(geneticcode)ChromosomesaremadeofDNAandprotein,andtheDNAisthegeneticcodeforthecharacteristicsandactivitiesofthecell.4.氧气从空气中扩散到血液以便在全身循环，而二氧化碳从血液散播到空气中以便排出体外。(diffuse)Oxygendiffusesfromtheairtothebloodtobecirculatedthroughoutthebody,butcarbondioxidediffusesfromthebloodtotheairtobeexhaledfromthebody.5.科学不断地提供新的发现，从而进一步支持了他的假设。(backup)Sciencecontinuedtothrowupdiscoverieswhichfurtherbackeduphishypothesis.UNIT21.Ateitherendoftheagespectrum,however,temperatureregulationmaynotbeaspreciseasitisinolderchildrenoryoungeradults.然而，在年龄段两端的人群，其体温调节精确程度都不如青少年或青年人。2.Thepathwaysofheatlossfromthebodyaretheskin,respiratorytract,andtoalesserextent,theurinaryanddigestivetracts.人体散热途径是经皮肤、呼吸道，少量经尿道和消化道散热。3.Changesinbodytemperaturealsohaveaneffectonmetabolicrateandheatproduction.Thisbecomesclinicallyimportantwhenapersonhasafever,anabnormallyhighbodytemperature.人体体温的变化也会影响代谢率和产热。当一个人发热、体温异常升高时，从临床上讲，体温变化就显得重要了。4.Anabolismmeanssynthesisor“formation”reactions,thebondingtogetherofsmallermoleculestoformlargerones.合成代谢是指综合或“形成”性反应，即把小的分子结合在一起形成更大的分子。5.Catabolismmeansdecomposition,thebreakingofbondsoflargermoleculestoformsmallermolecules.Cellrespirationisaseriesofcatabolicreactionsthatbreakdownfoodmoleculestocarbondioxideandwater.分解代谢是指分解，即将较大的分子链分解形成小分子。细胞呼吸过程就是一连串的分解代谢反应---将食物分子分解成二氧化碳和水。1.新陈代谢是指发生在生物体内的化学过程，可分为合成代谢和分解代谢两大类。(metabolism)Metabolismreferstothechemicalreactionsthattakeplaceinthelivingorganisms.Itmaybedividedintotwomajorcategories:anabolismandcatabolism.2.正常人的体温为37度。随个体、年龄、活动量和每日早晚略有差异，但波动幅度不超过l℃。(fluctuation)Thenormalbodytemperatureis37ºC,andvariesbyperson,age,activity,andtimeofday,butthefluctuationsareusuallynomorethan1.0ºC.3.在正常情况下，人体通过体温调节系统使体温保持相对稳定。(constant)Undernormalconditions,humanbodyisabletomaintainarelativelyconstantbodytemperaturethroughthesystemoftemperatureregulation.4.与生活在热带地区的人相比，在寒冷气候下生活的人，新陈代谢率要高10-20%。(metabolicrate)Peoplewholiveincoldclimatesmayhavemetabolicrates10%to20%higherthanthosewholiveintropicalregions.5.人体体温的调节主要是通过汗腺的分泌及皮肤血管的收缩与舒张。(excretion)HumanbodytemperatureismainlyregulatedthroughtheexcretionofsweatglandandvasodilationandconstrictionofbloodvesselsintheskinUNIT31.VentricularcontractionforcesbloodagainsttheflapsoftherightandleftAVvalvesandclosesthem;theforceofbloodalsoopenstheaorticandpulmonarysemilunarvalves.心室收缩使血液施压于左右房室瓣并使其关闭；血液的压力也使主动脉半月瓣和肺动脉半月瓣打开。2.Palpationsareusuallynotserious,andmaybetheresultoftoomuchcaffeine,nicotine,oralcohol.Muchmoreseriousisventricularfibrillation,averyrapidanduncoordinatedventricularbeatthatistotallyineffectiveforpumpingblood.心悸通常不很严重，可能因摄入的咖啡因，尼古丁或酒精过量引起。更为严重的是室颤，室颤是一种快速而无节律的心室跳动，可以导致心脏泵血无力。3.Althoughtheheartgeneratesandmaintainsitsownbeat,therateofcontractioncanbechangedtoadapttodifferentsituations.Thenervoussystemcananddoesbringaboutnecessarychangesinheartrateaswellasinforceofcontraction尽管心脏自身产生跳动并得以维持跳动，但为了适应不同情况还可以改变收缩率。神经系统可以，并的确能使心率和收缩的强度进行必要的改变。4.Theheartwillalsobetheeffectorinareflexstimulatedbyadecreaseintheoxygencontentoftheblood.Theaorticreceptorsarestrategicallylocatedsoastodetectsuchanimportantchangeassoonasbloodleavestheheart.心脏在受到血氧量下降激起的反射中起到效应器的作用。主动脉感受器的位置非常关键，所以在血液离心时，感受器能探查出其重要的变化。5.Thecardiaccycleisasequenceofmechanicaleventsthatisregulatedbytheelectricalactivityofthemyocardium.Cardiacmusclecellshavetheabilitytocontractspontaneously,thatis,nerveimpulsesarenotrequiredtocausecontraction.心循环是一系列受到心肌电活性调节的机械性活动。心肌细胞能自主收缩，即不需要神经冲动引起收缩。1.房颤是一种常见的不规律的心脏节律，房颤能引起心房，即心脏上腔室不正常收缩。（atrialfibrillation）Atrialfibrillationisaverycommonirregularheartrhythmthatcausestheatria,theupperchambersoftheheart,tocontractabnormally.2.心电图是用电来记录心脏的活动，其作用是协助诊断动脉疾病、心肌梗塞及一些先天性心脏病。（electrocardiogram）Theelectrocardiogram(ECG)isanelectricalrecordingofheartactionandaidsinthediagnosisofarterydisease,myocardialinfarction,andsomecongenitalheartdiseases.3.强烈要求高等教育改革的呼声遍及全国，人大代表对此也做了提案。(permeate)Astrongdesireforhighereducat