醫(yī)學(xué)專業(yè)英語(yǔ)chapter5respiratorysystem

1、Chapter5RespiratorySystemInthispassageyouwilllearn:TheorgansoftherespiratorysystemThestructureandfunctionoftheseorgansThemechanismofbreathingThegastransportandcleaningsystemAlllivinganimalsmusttakeinoxygenandgetridofcarbondioxide.Inthevertebratesanimalswithbackbonesthatgettheiroxygenfromtheair,botht

2、asksareperformedbyspecialgas-exchangeorganscalledlungs.Thelungsprovideaplacewhereoxygencanreachthebloodandcarbondioxidecanberemovedfromit.Theyareequippedwithtubesandabellowssystemfordrawinginairfromtheoutside,whilethepulmonaryveinsandarteriescirculatebloodthroughfrominside.Thelungsalsohaveacleanings

3、ystemthattraps,ejects,ordestroysirritantsandotherharmfulsubstancesthattravelinwiththeair.Inthesimplercold-bloodedamphibiansandreptiles,thelungsaretwoballoon-likesacs.Inactiveanimalsthatrequirelargeamountsofoxygen,especiallythewarm-bloodedbirdsandmammals,thelungsareaspongylabyrinthofsacsthatsupplyane

4、normoussurfaceareaforthetransferofgases.Intheadulthumanthetotallungsurface,ifflattenedout,wouldbelargerthanabadmintoncourt,about100squareyards(83squaremeters).Airentersthebodythroughthenoseandpassesthroughthenasalcavity,whichislinedwithamucousmembraneandfinehairs(cilia)tohelpfilteroutforeignbodies,a

5、swellastowarmandmoistentheair.Paranasalsinusesarehollow,air-containingspaceswithintheskullthatcommunicatewiththenasalcavity.They,too,haveamucousmembraneliningandfunctiontoprovidethelubricatingfluidmucus.aswellastolightenthebonesoftheskullandhelpproducesound.Afterpassingthroughthenasalcavity,theairne

6、xtreachesthepharynx(throat).Therearethreedivisionsofthepharynx.Thenasopharynxisthefirstdivision,anditisnearesttothenasalcavities.Itcontainstheadenoids,whicharemassesoflymphatictissue.Theadenoids(alsoknownasthepharyngealtonsils)aremoreprominentinchildren,andifenlarged,theycanobstructairpassageways.Be

7、lowthenasopharynxandclosertothemouthistheseconddivisionofthepharynx,theoropharynx.Thepalatinetonsils,tworoundedmassedoflymphatictissue,arelocatedintheoropharynx.Thethirddivisionofthepharynxisthehypopharynx(alsocalledthelaryngopharynx).Itisinthehypopharyngealregionthatthepharynx,servingasacommonpassa

8、gewayforfoodfromthemouthandairfromthenose,dividesintotwobranches,thelarynx(voicebox)andtheesophagus.Theesophagusleadsintothestomachandcarriesfoodtobedigested.Thelarynxcontainsthevocalcordsandissurroundedbypiecesofcartilageforsupport.Soundsareproducedasairisexpelledpastthevocalcords,andthecordsvibrat

9、e.Thetensionofthevocalcordsdeterminesthehighorlowpitchofthevoice.Sincefoodenteringfromthemouthandairenteringfromthenosemixinthepharynx,whatpreventsthepassingoffoodordrinkintothelarynxandrespiratorysystemafterithasbeenswallowedEvenwithasmallquantityofsolidorliquidmatterfindingitswayintotheairpassages

10、,breathingcouldbeseriouslyblocked.Aspecialdeterrenttothiseventisprovidedforbyaflapofcartilageattachedtotherootofthetonguethatactslikealidoverthelarynx.Thisflapofcartilageiscalledtheepiglottis.Theepiglottisliesovertheentrancetothelarynx.Intheactofswallowing,whenfoodandliquidmovethroughthethroat,close

11、soffthelarynx,sothatthesethingscannotenter.Onitswaytothelungs,airpassesfromthelarynxtothetrachea(windpipe),averticaltubeabout41incheslongand1inchindiameter.Thetracheaiskeptopenby16-202theepiglottisC-shapedringsofcartilageseparatedbyfibrousconnectivetissuethatstiffensthefrontandsidesofthetube.Inthere

12、gionofthemediastinum,theintotwobranchescalledbronchi.Eachbronchusleadstoaseparatetracheadivideslunganddividesandsubdividesintosmallerandfinertubes,somewhatlikethebranchesofatree(seeFigure6-1).DiaphragmFigure6-1Thesmallestofthebronchialbranchesarecalledbronchioles.Attheendofthebronchiolesareclusterso

13、fairsacscalledalveoli.Eachalveolusismadeofaone-celllayerofepithelium.Theverythinwallallowsfortheexchangebetweenthealveolusandthecapillariesthatsurroundandcomeinclosecontactwithit.Thebloodthatflowsthroughthecapillariesacceptstheoxygenfromthealveolusanddepositscarbondioxideintothealveolustobeexhaled.O

14、xygeniscombinedwithahemoglobininerythrocytesandcarriedtoallpartsofthebody.Eachlungisenvelopedinadouble-foldedmembranecalledthepleura.ofgasesTheouterlayerofthepleura,nearesttheribs,istheparietalpleura,andtheinnerlayer,closesttothelung,isthevisceralpleura.Thepleuraismoistenedwithaseroussecretionthatfa

15、cilitatesthemovementsofthelungswithinthethorax.Thetwolungsarenotquitemirrorimagesofeachother.Therightlung,whichistheslightlylargerofthetwo,isdividedintothreelobes,ordivisions,andtheleftlungisdividedintotwolobes.Itispossibleforonelobeofthelungtoberemovedwithoutdamagetotherest,whichcancontinuetofuncti

16、onnormally;Theuppermostpartofthelungiscalledtheapex,andthelowerareaisthebase.Thehilumofthelungisthemidlineregionwherebloodvessels,nerves,andbronchialtubesenterandexittheorgan.Thelungsextendfromthecollarbonetothediaphragminthethoraciccavity.Thediaphragmisamuscularpartitionthatseparatesthethoracicfrom

17、theabdominalcavityandaidsintheprocessofbreathing.Thediaphragmcontractsanddescendswitheachinhalation(inspiration).Thedownwardmovementofthediaphragmenlargestheareainthethoraciccavityandreducestheinternalairpressure,sothatairflowsintothelungstoequalizethepressure.Whenthelungsarefull,thediaphragmrelaxes

18、andelevates,makingtheareainthethoraciccavitysmaller,andthusincreasingtheairpressureinthethorax.Airthenisexpelledoutofthelungstoequalizethepressure;thisiscalledexhalation(expiration).Otherpartsarealsoinvolvedintheprocess.Thecycleofrespirationreallybeginswhenthephrenicnervestimulatesthediaphragmtocont

19、ractandflatten.Also,theintercostalmusclesbetweentheribsaidininspirationbypullingtheribsupandout.Themeasureofhoweasilythelungsexpandunderpressureiscompliance.Breathingisregulatedunconsciouslybycenterinthebrainstem.Thesecentersadjusttherateandrhythmofbreathingaccordingtochangesinthecompositionoftheblo

20、od,especiallytheconcentrationofcarbondioxide.GasTransport.Oxygeniscarriedinthebloodboundtohemoglobininredbloodcells.Theoxygenisreleasedtothecellsasneeded.Carbondioxideiscarriedinseveralways,butismostlyconvertedtoanacidcalledcarbonicacid.Theamountofcarbondioxidethatisexhaledisimportantinregulatingthe

21、acidityoralkalinityoftheblood.Iftoomuchcarbondioxideisexhaledbyhyperventilation,bodyfluidstendtobecomemorealkaline,aconditiontermedalkalosis.Iftoolittlecarbondioxideisexhaledasaresultofhypoventilation,bodyfluidstendtobecomemoreacid,aconditiontermedacidosis.Thecleaningsystemofthelungshasfourmaincompo

22、nents.Liningthetracheaandbronchialtreearecellsthatsecretemucus,whichtrapspollutantsandbacteria.Alsointhebronchiarecellscontainingtinycilia,thatprojectintotheblanketofmucusandwithconstantwavelikemotionspushthemucusupoutoftheairways.Irritatingchemicals,stagnantandexcessivemucus,andlargebitsofforeignma

23、tterareforciblyejectedassputumfromthebronchibyacough.Thisthirdimportantcleaningdevicelikebreathing,underpartialvoluntarycontrolisarapidmusclecontractionandbronchial-tubeconstrictionthatgeneratesawindforcefarstrongerthanatornado.Smallharmfulsubstancesthatmaketheirwayintothealveoliaredestroyedbythefou

24、rthlineofdefense,themacrophages.Thesearepatrollingcellsthatswallowupforeignparticlesordestroythemwithenzymes.NewWordsandPhrasesExercisesA.Discussthefollowingtopics:Imagineyouwerelecturinginfrontofruralhealthworkersonthetopicofrespiratorysystem,drawapicturetoillustratethewholesystem.Describetheirstru

25、cturesandfunctions.3.HowcanepiglottispreventthepassingfoodanddrinkintotherespiratorysystemWhatroledoesthediaphragmplayintheprocessofbreathingWhatarethefourcomponentsofthecleaningsystemHowdotheyfunctionB.Fillintheblankswiththewordsgivenbelowandchangetheirformsifnecessary.alveoluscapillarydiaphragmhem

26、oglobinthoraciccavitygasexchangeparietalpleuravisceralpleuramediastinumpleuralspaceThelungsaretwocone-shaped,spongyorgansconsistingofalveoli,bloodvessels,elastictissueandnerves.Eachofthetwolungsconsistsofsmallerdivisionscalledlobes;theleftlunghastwolobes,whiletherightlungisdividedintothreelobes.Inth

27、elungs,(1)aresurroundedbyanetworkoftinybloodvesselscalledcapillaries;oxygenfromthelungspassesintothese(2)fordistributiontotissuecells,whilecarbondioxidefromthebloodpassesintothelungstobeexpelledbyexhalation.Onceabsorbedintobloodcells,oxygenbecomesattachedto(3)andisreleasedtotissuecellsasneeded.Thus,

28、theprimaryfunctionofthelungsistobringairintoclosecontactwithblood,whichallows(4)tooccur.Thelungsaresurroundedbyamembranecalledthe(5).Thespacethatthelungsoccupywithinthechestiscalledthe(6),whichislinedbyamembranecalledthe(7).Theparietalandvisceralpleuraelieveryclosetoeachother;thesmallspacebetweenthe

29、sesmembranes,calledthe(8),isfilledwithafluidthatpreventsfrictionwhenthetwomembranesslideagainsteachotherduringrespiration.Inthecentralportionofthethoraciccavity(intheareabetweenthelungs)isaspacecalledthe(9),whichcontainstheheart.Agroupofsmoothmusclescalledthe(10)separatesthelowerportionofthethoracic

30、cavityfromtheabdomen.C.MatchColumnIwithColumnn.ColumnIColumnIIbronchiole1anyofthesmallsubdivisionofthebronchicompliance2thepeakportionofthelungsaconditioninwhichthereistoomuchcarbondioxidehypoventilation3inthebloodintercostal4betweentheribsparanasalsinuses5air-conditioningcavitiesinthebonesneartheno

31、seaconditioninwhichthereistoomuchcarbondioxideacidosis6inthebloodapex7weak,inadequateexchangeofgasroundedmassesoflymphtissueintheoropharynxpharynx8(palatinemeansroofofthemouth).alkalosis9inagreementwiththroat;composedofthenasopharynx,oropharynx,andpalatinetonsils10laryngopharynx.D.Definethefollowing

32、termsoftherespiratorysysteminlinewiththetextyouhavejust,learned(makinguseofthevocabularyprovidedinthebracketsifnecessary),forexam-ple:thegasneededbycellstoreleaseenergyfromfoodinmetabolismOxygen(gas,cell,releaseenergyfromfood,metabolism)1.mirrorimage(asseen,rightside,asif,leftside,viceversa)adenoids

33、(lymphatictissue,nasophar-ynx)3.alveolus(airsac,gasexchange,inrespiration)bronchus(mainbranch,trachea,mediastinum)5.epiglottis(leaf-shaped,cartilage,larynx,prevent,trachea)6.hyperventilation(extreme,rapid,deep,resultin,alkalosis)diaphragm(dome-shaped,muscle,move,increase,decrease,space,thoraciccavit

34、y)pharynx(common,passageway,esophagus,food,air,larynx)pleura(double-layered,membrane,visceralpleura,pariatalpleura,tho-raciccavity)sputum(substance,releases,coughing,clearingthethroat,res-piratorytract)E.TranslatethefollowingintoEnglish.1.副鼻竇2.口咽3.脊椎動(dòng)物4.肺泡5.二氧化碳6.肺換氣不足7.橫膈膜神經(jīng)8.兩重折疊的9.威懾物10.潤(rùn)滑液11.滯痰1

35、2.食管13.縱隔14.哺乳動(dòng)物15.堿中毒16.迷宮17.污染物質(zhì)18.腦干19.上皮；上皮細(xì)胞20.刺激物PassageTwoRespiratoryDisordersandDiseasesInthispassageyouwilllearn:VariousdisordersanddiseasesoftherespiratorysystemTheirdefinitions,causesandtreatmentDetaileddescriptionofthesignsandsymptomsofchronicobstructivepulmonarydiseaseMedicaltermspertai

36、ningtothediseasesoftherespiratorysystemTherespiratorysystemissubjecttoawidevarietyofdisordersanddiseases.Themostfrequentattackscomefromcommoncoldandfluviruses.Otherdiseasesthataffectthelungsincludebacterialinfectionssuchaspneumoniaandtuberculosis.Thelungsareespeciallyvulnerabletoallergicdis-easessuc

37、hasasthma.Therearemoreseriousdiseasessuchasrespiratorydistresssyndrome,em-physema,chronicobstructivepulmonarydiseases(COPD),lungcancer,etc.Influenzaandpneumonia.Influenzaisaviraldiseaseoftherespiratorytract.Differentstrainsoftheinfluenzavirushavecausedseriousepidemicsthroughhistory.Pneumoniaiscaused

38、byseveraldifferentmicroorganisms.Thenamerepresentsanyinflammationofthelungscausedbyin-fection,soanalternatetermforpneumoniaispneumonitis.Streptococcalpneumoniausuallyin-volvesoneormorelobesofthelunganddescribedaslobarpneumonia.Otheragentsofpneumonialocalizeinthebronchialtubes,causingbronchopneumonia

39、.Pleurisyisseverechestpainaccompanyingeachdeepbreathinapersonwithaninflamedpleura,thetwinmembranesaroundeachlungandliningthechestcavity.Pleurisycanattendpneu-moniaorresultfromdirectinfectionofthepleura.Tuberculosis(TB)hasincreasedinrecentyearsalongwiththeriseofAIDSandtheappear-anceofresistancetoanti

40、bioticsintheorganismthatcausesthedisease.Thenameofthediseasecomesfromthesmalllesions,ortubercles,thatappearwiththeinfection.ThesymptomsofTBin-cludefever,weightloss,weakness,cough,andasaresultofdamagetobloodvesselsinthelungs,hemoptysis,i.e.thecoughingupofphlegm(sputum)containingblood.Accumulationofex

41、udateinthealveolimayresultinsolidificationorconsolidationoflungtissue.Thetuberculintestisusedtorevealtuberculosisinfection,PPD(purifiedproteinderivative)istheformoftuberculincommonlyused.Asthma.Attacksofasthmaresultfromnarrowingofthebronchialtubes.Theconstriction,a-longwithedema,swellingofthebronchi

42、allinings,andaccumulationofmucusresultsinwheezing,extremedyspneaandcyanosis.Althoughthecauseofasthmaisuncertain,foreignparticlessuchaspollenorcertainenvironmentalpollutantsarebelievedtobetheculprits,whichstimulatethesmoothmuscleofthebronchialtreetoreleaseshistaminecausingthemuscletocontract.Thebronc

43、hialair-waysareconsequentlyrestricted.Treatmentofasthmaincludesremovalofallergens,administrationofbronchodilatorstowidentheairways,andadministrationofsteroids.Respiratorydistresssyndromeisadisorderofsomeprematurelybominfants.Thealveoliofafflictedbabiesarelinedwithaproteinmaterial,limitingtheamountof

44、oxygentheirbloodcanre-ceive.Thediseaseisoftenfatal.Mechanicalventilatorscanbeusedtohelpinfantsbreatheuntiltheirlungsbecomemoremature.Asaresultofsomeaccidentsanddiseases,suchaspolio,theres-piratorycenterornervescarryingitsimpulsesmaybeparalyzed.Treatmentmayinvolvecuttingaholethroughthewindpipeandpass

45、ingatubeattachedtoamechanicalrespiratorthroughthehole.Inothercases,thepatientmaybeplacedonaheartandlungmachinethatmaintainsrespirationandheartbeat.Acutepulmonaryedemaresultswhenfluidquicklyaccumulatesinthelungsandfillsthealveoli.Thefluidbuildupiscausedbyhearttroublethat,inturn,producesbackpressurein

46、thepulmonaryveinsandtheleftatriumofthehearttowhichtheycarryoxygen-richbloodfromthelungs.Apersonsufferingacutepulmonaryedemaissuddenlybreathlessandturnsbluebecauseofoxygen-poorblood.Theconditionistreatedwithoxygen,digitalistostrengthenheartaction,anddiureticstospeedfluidremovalbythekidneys.Pneumothor

47、axoccurswhenairgetsintothechestbetweenthepleurallining.Thelungthencannotfullyexpandandbreathingbecomesdifficult.Asaresult,thelungmayevencollapse.Pneumothoraxmayresultfromawoundinthechest,suchasaknifewound,orafterasuddentearinthelung.Infectionofthepleuralspacebygas-producingmicrobescanalsocausepneumo

48、thorax.Physicianstreatpneumothoraxbyremovingthegasbysuction,surgicallyrepairingthechestorlung,orprescribingantibioticswhenaninfectionispresent.Pneumoconiosis(blacklung)meansdustdisease.Itcanstrikeminersandindustrialwork-erswhoinhaledamagingamountsofdustoveralongperiodoftime.Oneofthemostseriousissili

49、-cosis,whichresultsfrominhalingquartzdust.Another,anthracosilicosis,arisesfrominhalationofcoalandquartzdust.Pneumoconiosisoftenoccursincombinationwithotherdiseases,suchasbron-chitisemphysema,ortuberculosis.Thereisnotreatmentforit,butthediseasecanbe,preventedbyminimizingdustinhalation.Emphysema.Thisi

50、sachronicdiseaseassociatedwithoverexpansionanddestructionofthealveoli.Commoncausesareexposuretocigarettesmokeandotherformsofpollution,aswellaschronicinfection.Emphysemaisthemaindisorderincludedundertheheadingofchronicobstructivepulmonarydisease(COPD),whichwillbediscussedindetailsoon.Chronicobstructi

51、vepulmonarydisease(COPD)isaratherbroadtermusedtodescribesim-plechronicbronchitis,chronicobstructivebronchitis,asthmaticbronchitisandemphysema,foritisconvenienttodescribevariouscombinationsofthesedisordersthatmaycoexist,forinstance,pa-tientsoftenhavechronicobstructivebronchitisaswellasemphysema.Unfor

52、tunately,chronicbronchitishasbeenusedvariablytorefertoasimplesmokerscoughor,asintheBritishliterature,tosevereCOPD.Inthisdiscussion,chronicbronchitiswillbecon-sideredsimple,obstructive,orasthmatictoreduceambiguity.Itisusefulclinicallytodif-ferentiatebetweentheextremelycommonsimplechronicbronchitisand

53、thelesscommonbutoftendevastatingformofchronicobstructivebronchitis.Simplechronicbronchitis,asyndromecharacterizedprimarilybyachronicproductivecough,istheresultoflow-gradeexposuretobronchialirritantsinanindividualwithouthyperreac-tiveairways.Thissyndromeisassociatedwithenhancedmucoussecretion,reduced

54、ciliaryactivity,andimpairedresistancetobronchialinfection.Simplechronicbronchitisisdefinedinclinicalterms:(1)excessiveproductionofmucus;(2)presenceofsymptoms,largelycough,onmostdaysforatleastthreemonthsannuallyduringtwoormoresuccessiveyears;(3)exclusionofbronchiecta-sis,tuberculosis,orothercausesoft

55、hesesymptoms.Thetermdoesnotdescribetheunderlyingpro-cess,whichmayvarywidely.Thepatientpopulationrangesfromthosewhoareasymptomaticexceptforamorningcigarettecoughproductiveofmucusinsmallamounts(simplechronicbronchitis)topatientswithaseveredisablingconditionmanifestedbyincreasedresistancetoairflow,hypo