（完整版）醫(yī)學英語（閱讀一分冊）翻譯及答案

（完整版）醫(yī)學英語（閱讀一分冊）翻譯及答案Chapter1Passage1HumanBodyInthispassageyouwilllearn:1.Classificationoforgansystems2.Structureandfunctionofeachorgansystem3.AssociatedmedicaltermsTounderstandthehumanbodyitisnecessarytounderstandhowitspartsareputtogetherandhowtheyfunction.Thestudyofthebody'sstructureiscalledanatomy;thestudyofthebody'sfunctionisknownasphysiology.Otherstudiesofhumanbodyincludebiology,cytology,embryology,histology,endocrinology,hematology,immunology,psychologyetc.了解人體各部分的組成及其功能，對于認識人體是必需的。研究人體結構的科學叫解剖學；研究人體功能的科學叫生理學。其他研究人體的科學包括生物學、細胞學、胚胎學、組織學、內(nèi)分泌學、血液學、遺傳學、免疫學、心理學等等。Anatomistsfinditusefultodividethehumanbodyintotensystems,thatis,theskeletalsystem,themuscularsystem,thecirculatorysystem,therespiratorysystem,thedigestivesystem,theurinarysystem,theendocrinesystem,thenervoussystem,thereproductivesystemandtheskin.Theprincipalpartsofeachofthesesystemsaredescribedinthisarticle.解剖學家發(fā)現(xiàn)把整個人體分成骨骼、肌肉、循環(huán)、呼吸、消化、泌尿、內(nèi)分泌、神經(jīng)、生殖系統(tǒng)以及感覺器官的做法是很有幫助的。本文描繪并闡述了各系統(tǒng)的主要部分。Theskeletalsystemismadeofbones,jointsbetweenbones,andcartilage.Itsfunctionistoprovidesupportandprotectionforthesofttissuesandtheorgansofthebodyandtoprovidepointsofattachmentforthemusclesthatmovethebody.Thereare206bonesinthehumanskeleton.Theyhavevariousshapes-long,short,cube-shaped,flat,andirregular.Manyofthelongboneshaveaninteriorspacethatisfilledwithbonemarrow,wherebloodcellsaremade.骨骼系統(tǒng)由骨、關節(jié)以及軟骨組成。它對軟組織及人體器官起到支持和保護作用，并牽動骨胳肌，引起各種運動。人體有206根骨頭。骨形態(tài)不一，有長的、短、立方的、扁的及不規(guī)則的。許多長骨里有一個內(nèi)層間隙，里面充填著骨髓，這即是血細胞的制造場所。Ajointiswherebonesarejoinedtogether.Theconnectioncanbesoclosethatnomovementispossible,asisthecaseintheskull.Otherkindsofjointspermitmovement:eitherbackandforthinoneplane-aswiththehingejointoftheelbow-ormovementaroundasingleaxis-aswiththepivotjointthatpermitstheheadtorotate.Awiderangeofmovementispossiblewhentheball-shapedendofonebonefitsintoasocketattheendofanotherbone,astheydointheshoulderandhipjoints.關節(jié)把骨與骨連接起來。顱骨不能運動，是由于骨與骨之間的連接太緊密。但其它的關節(jié)可允許活動，如一個平面上的前后屈伸運動，如肘關節(jié)；或是繞軸心旋轉運動，如樞軸點允許頭部轉動。如果一根骨的球形末端插入另一根骨的臼槽里，大輻度的運動（如肩關節(jié)、髖關節(jié)）即成為可能。Cartilageisamoreflexiblematerialthanbone.Itservesasaprotective,cushioninglayerwherebonescometogether.Italsoconnectstheribstothebreastboneandprovidesastructuralbaseforthenoseandtheexternalear.Aninfant'sskeletonismadeofcartilagethatisgraduallyreplacedbyboneastheinfantgrowsintoanadult.軟骨是一種比一般骨更具韌性的物質(zhì)。它是骨連結的保護、緩沖層。它把肋骨與胸骨連結起來，也是鼻腔與內(nèi)耳的結構基礎。一個嬰兒的骨骼就是由軟骨組成，然后不斷生長、骨化，使嬰兒長大成人。Themuscularsystemallowsthebodytomove,anditscontractionsproduceheat,whichhelpsmaintainaconstantbodytemperature.Striatedmusclescanbeconsciouslycontrolled.Theendsofthesemusclesareattachedtodifferentbonesbyconnectivetissuebandssothatwhenthemusclecontracts,onebonemovesinrelationtotheother.Thismakesitpossibletomovethewholebody,aswhenwalking,ortomovejustonepartofthebody,aswhenbendingafinger.Contractionsoftheheartandsmoothmusclesarenotunderconsciouscontrol.Smoothmusclesarefoundinthewallsoforganssuchasthestomachandtheintestinesandservetomovethecontentsoftheseorgansthroughthebody.肌肉系統(tǒng)使軀體運動，肌肉收縮產(chǎn)生的熱有助于維持一個恒定的體溫。人體能夠有意識地控制條紋肌。結締組織使肌肉末端附著于不同的骨面上，所以當肌肉收縮時，兩骨彼此靠近而產(chǎn)生運動。這也就使整個人體可以運動起來，如走路，運動軀體某個部位，如彎曲手指。心臟收縮和平滑肌收縮就不是被意識所控制的。器官壁內(nèi)層的平滑肌，如胃腸壁的平滑肌把胃腸中的物質(zhì)運送到全身。Thecirculatorysystem.Allpartsofthebodymusthavenourishmentandoxygeninordertofunctionandgrow,andtheirwasteproductsmustberemovedbeforetheyaccumulateandpoisonthebody.Thecirculatorysystemdistributesneededmaterialsandremovesunneededones.Itismadeupoftheheart,bloodvessels,andblood,whichtogethermakeupthecardiovascularsystem.Thebloodisalsopartofthebody'sdefensesystem.Ithasantibodiesandwhitebloodcellsthatprotectthebodyagainstforeigninvaders.循環(huán)系統(tǒng)：機體的所有部分需要營養(yǎng)物質(zhì)和氧氣來使之發(fā)揮功能和生長，也需要在這些器官所產(chǎn)生的廢物積聚而危害生命之前將其排除。循環(huán)系統(tǒng)運送有用物質(zhì)，排泄廢物。心血管系統(tǒng)是循環(huán)系統(tǒng)的組成之一；心血管系統(tǒng)包括心臟、血管及血液。血液也是機體防御系統(tǒng)的一個部分，血液中有抗體及白細胞來防止機體受到外來的侵襲。Theheartisamusclethatisdividedintotwonearlyidenticalhalves:onehalfreceivesbloodfromthelungsandsendsittotherestofthebody,theotherhalfsendsbloodthathastraveledthroughthebodybacktothelungs.Whentheheartmusclecontracts,thebloodisforcedoutintoarteriesandenterssmallcapillaries.Bloodreturnstotheheartthroughveins.心臟是一塊被分為幾乎對等兩半的肌肉。一半吸收來自肺部的血液，并將血液運送到機體的其余部位，另一半使流經(jīng)全身的血液回流人肺。心臟收縮時，動脈把全身血液輸送到毛細血管。靜脈輸送血液返回心臟。Alsofunctioningincirculationisthelymphaticsystem.Someofthefluidthatsurroundscellsdoesnotreenterthebloodvesselsdirectly.Thisfluid,calledlymph,returnstotheheartbywayofanothersystemofchannels-thelymphvessels.Lymphnodesalongthesevesselsfilterthefluidbeforeitreenterstheblood.Thespleenisalargelymphaticorganthatfilterstheblood.淋巴系統(tǒng)也是循環(huán)系統(tǒng)的一個組成部分。一些細胞周圍的體液不是直接回流入血管通道，這種體液叫淋巴液，它是流經(jīng)另一個管道系統(tǒng)——淋巴管而回流人心臟。沿淋巴管的淋巴結將淋巴液過濾，過濾后再回流人血液。脾是一個過濾血液的大淋巴器官。Therespiratorysystemtakesinoxygenfromtheairandexpelscarbondioxideandwatervapor.Airentersthenoseandmouthandtravelsthroughthelarynx,andtrachea.Thetracheadividestoentereachofthetwolungsandthendividesmorethan20timestoformaverylargenumberofsmallairspaces.Oxygenfromtheairentersthebloodthroughcapillariesinthewallsoftheseairspaces,andthebloodreleasecarbondioxideintotheairspacestobeexhaled.呼吸系統(tǒng)從空氣中攝取氧氣，并將二氧化碳、水蒸氣排出體外?？諝饨?jīng)鼻腔、口腔人喉管、氣管。氣管分成左右支氣管，各連結左右肺，左右支氣管再分枝20多次，在終端形成大量微小的肺泡。從空氣攝取的氧氣流經(jīng)這些肺泡壁內(nèi)的毛細血管流入血液，血液再經(jīng)肺泡把釋放出的二氧化碳排出體外。Thedigestivesystemconsistsofatubeextendingfromthemouthtotheanus.Init,foodandfluidsaretakenin,movedthroughthebody,andbrokendownintosmallmoleculesthatareabsorbedintothecirculatorysystem.Thisbreakdown,knownasdigestion,isbothamechanicalandachemicalprocess.消化系統(tǒng)是一個從口腔直到肛門的管道。食物和液體在消化道里被吸收，在腸道里移動時，被分解成小分子物質(zhì)后再進入循環(huán)系統(tǒng)。這種分解，即消化，是一個機械過程，也是一個化學過程。Foodentersthroughthemouth,wherechewingandsalivastarttobreakitupandmakeiteasiertoswallow.Next,thefoodtravelsdownthroughtheesophagustothestomach.Contractionsofthestomach'smuscularwallcontinuetobreakdownthefoodmechanically,andchemicaldigestioncontinueswhenacidandenzymesaresecretedintothestomachcavity.食物進入口腔里，咀嚼和唾液開始將食物粉碎，使之便于吞咽。接著，食物經(jīng)食管人胃。胃肌壁的收縮繼續(xù)機械化地分解食物，而當酸和酶分泌入胃腔時，化學性消化開始。Theliquifiedfoodgraduallypassesintothesmallintestine.Inthefirstpartofthesmallintestine,calledtheduodenum,enzymesfromthepancreasareadded.Theseenzymescompletethechemicalbreakdownofthefood.Thedigestionoffatisaidedbybile,whichismadeintheliverandstoredinthegallbladder.Thesmallintestineofanadultisabout21feet(6.4meters)long.Mostofitslengthisdevotedtoabsorbingthenutrientsreleasedduringthesedigestiveactivities.液體化食物逐漸進入小腸。小腸的起始部分叫十二指腸，胰腺分泌的酶輔助食物消化。這些酶完成食物的化學分解。肝臟分泌的膽汁貯存在膽囊內(nèi)，膽汁有助于脂肪消化。一個成年人的小腸有21英尺（6.4米）長。小腸的大部分腸段用來吸收消化過程中釋放的營養(yǎng)物質(zhì)。Theliquidremainderofthefoodentersthelargeintestine,orcolon,whichisabout12feet(3.7meters)long.Itismorethantwiceaswideasthesmallintestine.Inthelargeintestinemostofthefluidisabsorbed,andtherelativelydryresiduesareexpelled.液狀的剩余食物進入大腸，或結腸，它大約有12英尺（3.7米）長。大腸是小腸的兩倍多寬。大部分液體在大腸內(nèi)被吸收，相對干化的殘余物被排出體外。Theurinarysystemmaintainsnormallevelsofwaterandofcertainsmallmoleculessuchassodiumandpotassiuminthebody.Itdoesthisbypassingbloodthroughthekidneys,twoefficientfilteringorgansthatgetridofanyexcessofvariousmoleculesandconservethosemoleculesthatareinshortsupply.泌尿系統(tǒng)維持水分及體內(nèi)某些小分子物質(zhì)，如鈉、鉀的正常水平。身體是通過讓’腎過濾血液來做到這一點的。腎是兩個有效的過濾器官，它濾出各種多余的小分子物質(zhì)，保留那些供應不足的小分子物質(zhì)。Thefluidthatleavesthekidneys,knownasurine,travelsthroughatubecalledtheuretertothebladder.Thebladderholdstheurineuntilitisvoidedfromthebodythroughanothertube,theurethra.從腎流出的液體，即尿，通過輸尿管人膀胱。膀胱起貯存尿液的作用，直到尿經(jīng)膀胱另一端的管道排出。Theendocrinesystem.Thetwosystemsthatcontrolbodyactivitiesaretheendocrinesystemandthenervoussystem.Theformerexertsitscontrolbymeansofchemicalmessengerscalledhormones.Hormonesareproducedbyavarietyofendocrineglands,whichreleasethehormonesdirectlyintothebloodstream.內(nèi)分泌系統(tǒng)。內(nèi)分泌和神經(jīng)是調(diào)控機體活動的兩個系統(tǒng)，前者依靠其化學信使——激素發(fā)揮作用。激素是由各種內(nèi)分泌腺體制造，并直接被釋放入血流Amajorglandisthepituitary,whichislocatedunderthebraininthemiddleofthehead.Itproducesatleasteighthormones,whichaffectgrowth,kidneyfunction,anddevelopmentofthesexorgans.Becausesomeofthepituitary'shormonesstimulateotherglandstoproducetheirownhormones,thepituitarycalledthemastergland.腦垂體是一個主要腺體，它位于頭中部腦下方。它至少分泌八種激素，這些激素對人體生長、肝功能及性器官發(fā)育有影響。因為腦垂體分泌的一些激素促進其他腺體分泌激素，所以腦垂體是主要腺體。Anothergland,thethyroid,islocatedbetweenthecollarbones.Itshormonecontrolstherateofthebody'smetabolism.Thesexorgans(ovariesendtestes)makethesexcellsandalsomakehormonesthatcontrolcertaincharacteristicsofmalesandfemales.Locatedontopofeachkidneyistheadrenalgland,whichproducescortisoneandadrenaline.Thepancreasproducesnotonlydigestiveenzymesbutalso3insulinandglucagon,whichcontrolthebody'suseofsugarandstarches.另一個腺體，甲狀腺，位于鎖骨之間。甲狀腺激素調(diào)控著機體新陳代謝的速度。性器官（卵巢、睪丸）分泌性細胞和性激素，這些激素控制著男性和女性的某些特征。每邊腎上方是腎上腺，它分泌可的松和腎上腺激素。胰腺不僅分泌消化酶，而且分泌胰島素和高血糖素，這兩種激素控制機體的糖分及淀粉的消耗。Thenervoussystem.Thebrain,thespinalcordandthenerve-alsocontrolsbodyactivities.Thelowerpartsofthebraincontrolbasicfunctionssuchasbreathingandheartrateaswellasbodytemperature,hunger,andthirst.Abovetheseregionsarethecentersforsight,sound,touch,smell,andtaste,andtheregionsthatdirectvoluntarymuscularactivitiesofthearmsandlegs.Performedherearethehigherfunctionsofintegratingandprocessinginformation.神經(jīng)系統(tǒng)——腦、脊髓及神經(jīng)，也調(diào)控機體活動。腦的偏下部位控制著諸如呼吸、心跳、體溫、饑渴的基本活動。而腦的偏上部位則是視覺、聽覺、觸覺、嗅覺及味覺中心，也是指揮臂、腿隨意肌肉運動的區(qū)域。神經(jīng)系統(tǒng)更高級的功能是整合、處理信息。Thebrainreceivesandsendsinformationbymeansofnerves,manyofwhichliepartlyinthespinalcord.Thespinalcordisprotectedbythespinalcolumn.Nervesenterandleavethespinalcordateachlevelofthebody,travelingtoandfromthearms,legs,andtrunk.Thesenervesbringinformationfromthevarioussenseorgans.Theinformationisprocessedbythebrain,andthenmessagesarecarriedbacktomusclesandglandsthroughoutthebody.腦通過神經(jīng)收集并傳送信息，許多神經(jīng)部分地分布在脊髓里。脊髓由脊柱保護。在機體每一級，神經(jīng)傳人、傳出脊髓，往返于臂、腿、軀體。這些神經(jīng)輸送來自各種感覺器官的信息。信息經(jīng)腦處理后輸送回全身及腺體Thereproductivesystemisconstructeddifferentlyformalesandfemales.Themalereproductivesystemisresponsibleforproducing,transportingandmaintainingviablesperm(themalesexcell).Italsoproducesthemalesexhormone,testosterone,whichregulatesthedevelopmentofabeard,pubichair,adeepvoiceandotherbodilycharacteristicsoftheadultmale.男、女性的生殖系統(tǒng)不同。男性生殖系統(tǒng)產(chǎn)生、輸送、維持能存活的精子（男性性細胞）。它也分泌男性激素、睪酮，以此調(diào)節(jié)胡須、陰毛、深沉嗓音極其他成年男子身體發(fā)育的特征。Thefemaleproductivesystemisresponsibleforproducingandtransportingova(thefemalesexcells),eliminatingovafromthebodywhentheyarenotfertilizedbysperm,nourishingandprovidingaplaceforgrowthofanembryowhenanovumisfertilizedbysperm,andnourishinganewbornchild.Thefemalereproductivesystemalsoproducesthefemalesexhormones,estrogenandprogesterone,whichregulatethedevelopmentofbreastsandotherbodilycharacteristicsofthematurefemale.女性生殖系統(tǒng)產(chǎn)生、輸送卵子（女性性細胞），將未受精的卵子排出體外，而當精、卵結合時，女性生殖系統(tǒng)培養(yǎng)、提供胚胎生長場所，并孕育新生兒。女性生殖系統(tǒng)也分泌女性性激素——雌激素和孕酮，以此調(diào)節(jié)乳房及其他成熟女性身體發(fā)育的特征。Theskinisacompletelayerthatprotectstheinnerstructuresofthebody,anditisthelargestofthebody'sorgans.Itkeepsoutforeignsubstancesandpreventsexcessivewaterevaporation.Thenervesintheskinprovidetactileinformation.Theskinalsohelpskeepthebody'stemperaturecloseto37°C,heatisconservedbyreducingbloodflowthroughtheskinorisexpendedbyincreasingbloodflowandbyevaporationofsweatfromtheskin.Hairandnailsareaccessorystructuresoftheskin.皮膚是保護肌體內(nèi)層結構的完整層，也是機體的最大器官。皮膚防御外來侵襲，防止過多水分蒸發(fā)。皮膚上的神經(jīng)提供觸覺信息。皮膚也能將體溫維持到98.6華氏度（約37攝氏度）。通過皮膚的血流量降低時，熱量就被儲存起來，通過皮膚的血流增加及汗液蒸發(fā)時，熱量就散發(fā)。頭發(fā)及指甲是皮膚的附屬結構。CellsandTissues細胞與組織Inthispassage,youwilllearn:1.Humanbodysystemsasawhole2.Vitalpartsofacell3.FourkindsoftissuesCellsareorganizedintotissues,andtissuesarearrangedintoorgans,whichinturnaregroupedintosystems.Eachbodysystemservesitsspecificfunctions.Bearinmindhoweverthatthebodyfunctionsasawhole----nosystemisindependentoftheothers.Theyworktogethertomaintainthebody’sstateofinternalstability,termedhomeostasis.Nowlet’sbeginourdiscussionwithcells,thesmallestunitoflivingmatterthatcanexistbyitself.細胞構成組織，組織構成器官，器官又進一步構成系統(tǒng)。人體的每個系統(tǒng)都有其特定功能，但是，請記住這里:機體是作為一個整體來發(fā)揮作用的，沒有哪個系統(tǒng)能夠獨立于其他系統(tǒng)而存在，是整體系統(tǒng)共同作用保持了機體內(nèi)部的穩(wěn)定狀態(tài)，即體內(nèi)平衡?，F(xiàn)在，我們先討論細胞─能獨立存在活性物質(zhì)的最小單位。Thebodycanbestudiedfromitssimplesttoitsmostcomplexlevel,beginningwiththecell.Allbodyfunctionsresultfromtheactivitiesofbillionsofthespecializedcells.Someplantsandanimalsconsistofonlyasinglecell.Othersarecomposedofmanybillionsofcells.從細胞開始，我們能夠從最簡單到最復雜的水平來研究機體。所有人體的功能都來自億萬個特定細胞活動，有的動植物僅由一個細胞構成，其他生物則由億萬個細胞構成。Cellsexistinavarietyofshapesandsizes.Theymay,forexample,becube-shapedorflat.Scientistswhostudycellshavedeterminedthatasinglecellmaybeaslargeasatennisballorsosmallthatthousandswouldfitonthepointofaneedle.Theyolkofahen’seggisactuallyaverylargecell.Bycontrast,bacteria----eachoneofwhichisatinycell----areamongthesmallestcells.Regardlessofitsshapeorsize,everycellcontainsthe“machinery”neededtomaintainlife.Whilenormallycellsfunctionwithgreatefficiency,theyaresubjecttovariousdisordersthatresultindisease.細胞有很多種形狀和大小。列如：有可能是立方形或扁形的。科學家的研究發(fā)現(xiàn)單獨一個細胞可以像網(wǎng)球一樣的大小，或小到幾千個細胞才能剛好填滿針頭。雞的蛋黃是一個非常大的單細胞。微小的細菌呢算是最小的細胞。不管是細胞大小或形狀的不同，每個細胞都有“需要存活的機制”。對每個正常的細胞，有效力的細胞，都存在許多問題，能導致疾病。Thesizeofcellsisusuallymeasuredinmicrons.Amicronisamillionthofameter,andabout25,000micronsequaloneinch.Thesmallestbacteriaareabout0.2micronindiameter.Theaveragecellinthehumanbody----abouttenmicronsindiameter----isaspeckbarelyvisiblewithouttheaidofamicroscope.細胞的大小是以“微米”為長度單位。微米是一米的一百萬分之一，25000微米等于一寸。最小的細菌的圓徑是0.2微米。人體正常細胞的評價圓徑約十微米，肉眼勉強可以看得到，不需要顯微鏡的幫助。Thestudyofcellsisthebranchofbiologycalledcytology.Thesciencethatdealswithcellsonthesmalleststructuralandfunctionalleveliscalledmolecularbiology.研究關于“細胞”是生物學的分支，成為細胞生物學。在最微小水平針對細胞的結構及功能的研究成為分子生物學。Allcellsconsistofprotoplasm,the“l(fā)ivingjelly.”Theprotoplasmofatypicalcellformsthreevitalparts----thecellmembrane,thecytoplasm,andthenucleus.Themembraneenclosestheothercellstructures.Muchofthechemicalworkofthecellisdoneinthecytoplasm,whichsurroundsthenucleus.Thenucleus,enclosedbyitsownmembrane,isthecontrolcenterofthecell.(seeFigure1-1)所有細胞都是以“原生質(zhì)”，又稱“生命膠質(zhì)”所形成的。典型細胞的原生質(zhì)形成了三個重要部分，細胞膜、細胞質(zhì)和細胞核。細胞膜圈住了細胞的其他結構。大部分的化學反應都在細胞核周圍，細胞質(zhì)完成的。被自己的膜包圍的細胞核是細胞的控制中心。thecellsMembrane細胞膜Cellscansurviveonlyinaliquidmediumthatbringsinfoodandcarriesawaywaste.Forone-celledorganismsthisfluidisanexternalbodyofwater----theocean,alake,orastream.Formany-celledplantsandanimals,however,themediumispartoftheorganism----inplants,thesap;inanimals,theblood.細胞只能存活在能供養(yǎng)分又能排除廢物的液體媒介中。對單細胞生物來說，這就是細胞外的液體，如：大海里、河里或水流中。在對多細胞生物而言，這種媒介就是生物體的一部分，植物以汁液的形式，動物以血液的形式。Thecellmembraneissemipermeable,ordifferentiallypermeable----somesubstancescanpassthroughit,butotherscannot.Thischaracteristicenablesthecelltoadmitusefulsubstancesandtorejectharmfulsubstancesfromthesurroundingfluidaswellastoforceout,orexcretewasteproductsintothefluid.細胞膜是半滲透性或區(qū)別性的滲透膜，即某些物質(zhì)能滲透。這個特殊性使細胞對細胞周圍只吸收了需要的物質(zhì)而排除掉有害的物質(zhì)，包括細胞內(nèi)的廢物通過液體化后排出細胞外。Thecellmembraneisanextremelythinbuttoughbandofproteinandphospholipidmolecules.Phospholipidsarechemicalssimilartostoredfat.Ontheevidenceofelectronmicrographs,biologistsbelievethatithasporesthroughwhichcertainsmallmoleculespassintact.Substancesprobablypassthroughthecellmembraneinseveralways.Smallchamberslocatedonthecellmembranecalledcaveolaegatherchemicalsignalsandchannelthemintothecells.Thecaveolaemayalsohelpdistributeproteinsthroughoutthecell.Largemoleculesenterthecellbyaprocesscalleddiffusion,inwhichtheymaybedissolvedbysubstancesinthecellmembrane.Theycanthenthroughthemembranewithoutdifficulty.Somecellstakeinlargemoleculesbymeansofpinocytosis.Inthisprocess,thecellmembraneformsapocketaroundlargemoleculesfloatingagainstit.Themolecule-and-fluid-filledpocketthenbreadsloosefromthemembranetobecomeabubblelikevacuole,andthevacuolethendriftsintothecytoplasm.Finally,thevacuolewallbreaksupandthemoleculesarereleasedintothecytoplasm.細胞膜是一種非常薄但確以很堅固的蛋白磷脂膜形成。磷脂是一種類似于儲存的脂肪的蛋白物質(zhì)。通過電子顯微鏡，生物學家相信細胞膜有孔，使較小的物質(zhì)完全可以通過。物質(zhì)可通過多種方式從細胞膜進入。細胞膜上的結構，稱“小穴”，可接受化學信號再傳到細胞內(nèi)。小穴還可能參于細胞蛋白的分配。大的分子可通過“滲濾”進入細胞內(nèi)，或被細胞膜內(nèi)體分解，使它們更容易的進入細胞內(nèi)。有些細胞可通過“胞飲”方式吞飲較大的物質(zhì)。這個過程是通過細胞膜在大物質(zhì)形成了“帶”把它包圍著，將它以泡狀的“液泡”引入細胞質(zhì)，最后包圍解散，大物質(zhì)成功的進入細胞內(nèi)。Thecytoplasm細胞質(zhì)Thecytoplasmismainlywater.Itswatercontentvariesfromaminimumofabout65percenttoamaximumofabout95percent.Thesolidsinthecytoplasmincludegranularproteins,carbohydrates,dropletsoffat,andpigments.Thecytoplasmisthusacolloidalsystem.細胞質(zhì)主要成分是“水”。水分含量有百分之65到最高，百分之95。細胞質(zhì)內(nèi)的固體包括蛋白顆粒、碳水化合物、脂肪小滴和色素。細胞質(zhì)是膠體性的。Thecytoplasmmaybeeitherwateryorsyrupy,dependingontheconcentrationofsolidsdispersedinthefluid.Whenthesolidcontentdecreases,thesestructuresseemtovanish.Changesinconcentrationalsoproduceanapparentsteamingofthecytoplasmfromplacetoplacewithinthecell.Thisoccurs,forexample,whenfoodmoleculesenterthecell.細胞質(zhì)可能是水性或糖漿性，根據(jù)散在細胞質(zhì)內(nèi)固體的濃度。當固體成分濃度增多，膜狀和纖維狀結果在細胞質(zhì)顯出。而當固體成分濃度減少時，膜狀和纖維狀的結構就消失。濃度的變化還可以表現(xiàn)細胞質(zhì)內(nèi)局部流動的變化。食物分子進入時可見。Mostofthecell’sconstantworkofkeepingaliveisperformedinthecytoplasm.Herefoodmoleculesarechangedintothematerialneededforenergyandmaterialsforgrowthorstiffeningofthecellmembranearemanufacturesneededbytherestoftheorganism.Forexample,plantcellscontainingchlorophyllmanufactureglucose----aplantfood----fromcarbondioxideandwater.大部分為了細胞存活的工作都在此處（細胞質(zhì)）完成的。在此處，食物物質(zhì)將被轉化成提供細胞能量的材料和提供細胞生長的材料，或細胞膜的增強劑所生產(chǎn)。多細胞植物的細胞質(zhì)還是生產(chǎn)了對其他生物提供食物的物質(zhì)。列如：植物葉綠素所產(chǎn)生的葡萄糖，植物的食物，從水和二氧化碳合成。Oneofthecytoplasm’skeyenergytransactionsoccursinthesausage-shapedmitochondria.Eachmitochondrionhasaninnerandanoutermembrane.Likethecellmembrane,themembranesofthemitochondrionaresemipermeable.Foodmoleculesthatpassintothecytoplasmaretakenintothemitochondriaandoxidized,orburned,forenergy.細胞質(zhì)能量轉換的要點發(fā)生在錐狀形的線粒體。每個線粒體都有內(nèi)膜和外膜。像細胞膜一樣，線粒體的膜也是半滲透性。進入線粒體的食物分子被氧化提供出能量。Theendoplasmicreticulum,anetworkofmembranoustubes,runsthroughthecytoplasm.Intheopinionofsomebiologists,thisnetworkisacontinuousstructurethatbeginsatthecellmembrane,twiststhroughthecytoplasm,andendsatthemembranesurroundingthenucleus.Locatedalongtheendoplasmicreticulumaswellaselsewhereinthecytoplasmarenumerousribosomes.Thesetinygranulesconsistinpartofribonucleicacid(RNA).Proteinsaremanufacturedattheribosomes.TheGolgicomplex,orGolgiapparatus,isamembranousstructurecomposedofstacksofthinsacs.NewlymadeproteinsmovefromtheendoplasmicreticulumtotheGolgicomplex,wheretheyarestoredforlatersecretion.胞漿網(wǎng)，在細胞質(zhì)中由膜所形成管狀的網(wǎng)。有些生物學家認為這是一種連續(xù)性結構，始點為細胞膜，在細胞膜內(nèi)扭絞，終點為細胞核的膜。分布于胞漿網(wǎng)包括細胞質(zhì)中某處的是核糖體。這些小顆粒是核糖核酸所形成的。蛋白質(zhì)是在核糖體合成的。高爾基體是膜狀囊包堆成層形成的。新合成的蛋白從胞漿網(wǎng)移動到高爾基體儲存，為了后來分泌所用。Vacuolesdriftthroughthecytoplasmandusuallycarryfoodmoleculesinsolution.Lysosomesarestructuressomewhatsimilarinappearancetovacuolesbutdenser.Theyappeartohaveadigestivefunction.Eachlysosomeisfilledwithdigestiveenzymesandencasedinamembrane.Lysosomesarebelievedtobreakdownfoodsubstancesbroughtintothecellbypinocytosis.IthasbeensuggestedthattheGolgicomplexplaysapartintheformationoflysosomes.在細胞質(zhì)內(nèi)游動的液泡一般是帶著食物分子的溶液。溶酶體是一種有點像液泡的結構，但較稠。它是用來消化的。每個溶酶體的膜內(nèi)都是添裝著消化酶。我們認為它是消化通過“胞飲”方式的大物質(zhì)。也認為高爾基體對溶酶體的形成有關系。TheNucleus細胞核Nearthecenterofthecellisaroundishoroval-shapednucleus.Thenucleuscontrolsthegrowthanddivisionofthecell.Italsocontainsthestructuresthattransmithereditarytraits.細胞的中央，圓形或橢圓形的就是細胞核。細胞核控制細胞的生長和分化。也裝著遺傳信息。Enclosedbyatwo-layeredmembrane,thenucleuscontainsaliquidcallednucleoplasmaswellasstrandsofdeoxyribonucleicacid(DNA)coveredwithacoatingofprotein.AstrandofDNAconsistsofalongseriesofgenes,whicharetheunitsofheredityofplantsandanimals.Genesdeterminethecharacteristicsofacell.TheydothisbyregulatingtheproductionofRNA,whichinturncontrolsthemanufactureofspecificproteins.被兩層膜圈住著，細胞核內(nèi)含有稱為“核質(zhì)（漿）”的液體和脫氧核糖核酸的蛋白層。脫氧核糖核酸縷是很長的基因系列所組成的，它是植物和動物的遺傳信息?；驔Q定了細胞的特征。它是通過調(diào)節(jié)核糖核酸，使核糖核酸產(chǎn)出特異的蛋白。Humancells,forexample,makeonlyproteinsuniquetohumanbeingsDNAstrandsareusuallytoothinlystrungouttobeseenwithanopticalmicroscope.Becausethestrandsarereadilystainedwithdyes,theyarecalledchromatin.Whenacellbeginstodivide,however,thechromatinthickensintotheformofchromosomes.列如：人的細胞，只產(chǎn)出人獨特擁有的蛋白。脫氧核糖核酸縷一般都很細小過光學顯微鏡能觀察到。因為脫氧核糖核酸縷能夠染色后部分被染，稱“染色質(zhì)”。細胞分化過程中，染色體拾起變厚形成了“染色體”。Anucleusnotundergoingdivisionhasatleastonenucleolus.ThenucleoluscontainsaconcentrationofRNA.BiologiststhinkRNAismadeinitiallyinthenucleusaccordingtoaDNA“blueprint”andstoredthereuntilneededforproteinmanufacture.細胞核分化核仁不會減少，最少要有一個核仁。核仁含有豐富的核糖核酸。生物學家認為核糖核酸原本在核仁里，根據(jù)脫氧核糖核酸的藍圖造出而藏在此處直到有蛋白合成的需要。thenucleusofanimalcellsisasphericalstructurecalledthecentrosome,fromwhichastersradiate.Thecentrosomecontainsapairofroddedstructurecalledcentrioles,whichusuallylieatrightanglestoeachother.Althoughcentriolesandcentrosomeshavenotbeenseeninplantcells,biologistsbelievethatplantcellscontainsimilarstructures.靠近動物的細胞核的圓形結構叫“中心體”，可見呈放射狀散發(fā)的星體。中心體內(nèi)含有一對棍狀結構，稱為“中心粒”，一般都形成正確固定的角度。無法在植物細胞發(fā)現(xiàn)中心體和中心粒，但生物學家認為植物應該有存在類似功能的其他結構。Tissues組織Cellsareorganizedintotissuesthatperformspecificfunctions.Thefourbasictissuetypesareasfollows:多細胞組成了組織，為了特異的功能。四種基本的組織：Epithelialtissues----coversandprotectsbodystructuresandlinesorgans,vessels,andcavities.上皮組織:覆蓋及保護著身體結構和分清器官、導管和空腔。Connectivetissues----supportsandbindsbodystructures.Itcontainsfibersandothernonlivingmaterialbetweenthecells;includedarefattissues,cartilage,boneandblood.結締組織:支柱和聯(lián)結著身體結構。包括細胞之間的纖維和其它無生物結構。包括脂肪組織、軟骨、骨頭和血液。Muscletissues----contractstoproducemovement.Thethreetypesare：skeletalorvoluntarymusclethatmovestheskeleton;thecardiacmuscleoftheheart;andthesmoothmusclethatformsthewallsoftheabdominalorgans.Cardiacandsmoothmusclecanfunctionwithoutconsciouscontrolandarethusdescribedasinvoluntarymuscle.肌肉組織:通過收拾來產(chǎn)生動作。分為三種：骨骼肌，作用于一般骨骼移動。心機，心臟的肌肉。平滑肌，形成胃腸道壁的肌肉。心機和平滑肌是非意識性，不隨意性肌肉。Nervoustissue——makesupthebrain,spinalcord,andnerves.Itcoordinatesandcontrolsbodyresponsesbytransmittingelectricalimpulses.神經(jīng)組織:組成大腦、脊椎和神經(jīng)。它是通過動作電位來超空身體。Thesimplesttissuesaremembranes.Mucousmembranessecretethickfluidcalledmucusthatprotectsunderlyingtissues.Serousmembranessecreteathin,wateryfluid.Theylinebodycavitiesandcoverorgans.最簡單的組織就是膜。粘液膜分泌出粘稠的膠液，起得組織保護作用。粘液組織分泌出較稀的粘液，起得身體導管的分界和覆蓋著各個器官。HumandiseasesInthispassageyouwilllearn:1.diseaseandpathology2.theclassificationofdiseases3.germs’invasionofthehumanbody4.thebody’sdefenseagainstinvasion5.thebody’simmunitytodiseasesThebriefsurveyofthehumanbodyinChapterOnehasgivenusaglimpseintotwodifferentstudiesthatareconsideredthefundamentalsofmedicalsciences,namelyanatomyandphysiology.However,thepictureisnotcompletewithoutconsideringpathology,thesciencethatdealswiththestructuralandfunctionalchangesproducedbythedisease.Infact,themodernapproachtothestudyofdisorderemphasizesthecloserelationshipofthepathologicalandphysiologicalaspectsandtheneedtounderstandthefundamentalsofeachintreatinganybodydiseases.第一章中，通過對人體的概論，即解剖學與生理學，我們對兩種被認為是醫(yī)學基礎的不同學科有了一個大致的印象。然而如果我們不考慮病理學，這門涉及由疾病帶來的結構和功能變化的學科，上述的人體概論就不是完整的。實際上，現(xiàn)代對疾病的研究方法強調(diào)了病理學與生理學方面的密切關系，強調(diào)了我們在治療任何人體疾病方面需要了解病理學與生理學基礎的重要性。Thenwhatisadisease?Itmaybedefinedasaconditionthatimpairstheproperfunctionofthebodyorofoneofitsparts.Everylivingthing,bothplantsandanimals,cansuccumbtodisease.People,forexample,areofteninfectedbytinybacteria,butbacteria,inturn,canbeinfectedbyevenmoreminuteviruses.那么什么是疾病呢？它可能被定義為正常的功能或是部分功能遭受損害時的一種狀態(tài)。每一種生物、植物和動物，都會受制于疾病。例如，人類常常被微小的細菌所感染，但是，反過來說，細菌又能夠被甚至更加微小的病毒所感染。Hundredsofdifferentdiseasesexist.Eachhasitsownparticularsetofsymptomsandsigns,cluesthatenableaphysiciantodiagnosetheproblem.Asymptomissomethingapatientcandetect,suchasfever,bleeding,orpain.Asignissomethingadoctorcandetect,suchasaswollenbloodvesseloranenlargedinternalbodyorgan.許多種疾病存在于世。每一種都有其特定的癥狀、征兆和線索，醫(yī)生能以此診斷疾病之所在。癥狀是病人自己就能覺察到的，比如，高燒、流血，或是疼痛。而征兆則是醫(yī)生能夠觀察到的，比如，血管擴張或是體內(nèi)器官腫大。Diseasescanbeclassifieddifferently.Forinstance,anepidemicdiseaseisonethatstrikesmanypersonsinacommunity.Whenitstrikesthesameregionyearafteryearitisanendemicdisease.Anacutediseasehasaquickonsetandrunsashortcourse.Anacuteheartattack,forexample,oftenhitswithoutwarningandcanbequicklyfatal.Achronicdiseasehasaslowonsetandrunsasometimesyears-longcourse.Thegradualonsetandlongcourseofrheumaticfevermakesitachronicailment.Betweentheacuteandchronic,anothertypeiscalledsubacute.疾病可以劃分為不同的種類，例如，流行病是一種在某一社區(qū)內(nèi)侵襲許多人的疾病。當它年復一年地襲擊同一社區(qū)，就成了一種地方病。急性病發(fā)作快，但病程短，舉個例子來說，急性心臟病發(fā)作常常沒有前兆，而且會很快致命。慢性病發(fā)作則慢，但病程有時會長達幾年之久。風濕熱正是由于發(fā)病慢、病程長而成為一種慢性失調(diào)?。圆。?。而介于急性與慢性之間的另一種類型，就被稱為亞急性。Diseasescanalsobeclassifiedbytheircausativeagents.Forinstance,aninfectious,orcommunicable,diseaseistheonethatcanbepassedbetweenpersonssuchasbymeansofairbornedropletsfromacoughorsneeze.Tinyorganismssuchasbacteriaandfungicanproduceinfectious