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1、RespiratorySystemTherespiratorysystemcanbedividedintotwoparts:Theupperrespiratorytracts:mouth,nose&nasalcavity,pharynxandlarynxThelowerrespiratorytracts:trachea,bronchi,bronchioles,alveoli,diaphragmandlungsFunctionTransportsairintothelungsandfacilitatesthediffusionofoxyge
2、nintothebloodstream.Italsoreceiveswastecarbondioxidefromthebloodandexhalesit.Mouth,nose&nasalcavity:Thefunctionofthispartofthesystemistowarm,filterandmoistentheincomingair.Pharynx:Herethethroatdividesintothetrachea(windpipe)andesophagus(foodpipe).Thereisalsoasmallflapofca
3、rtilagecalledtheepiglottiswhichpreventsfoodfromenteringthetrachea.Larynx:Thisisalsoknownasthevoiceboxasitiswheresoundisgenerated.Itcontainsthevocalcords.Italsohelpsprotectthetracheabyproducingastrongcoughreflexifanysolidobjectspasstheepiglottis.TheUpperRespiratoryTractsTr
4、acheaMuscularcartilaginoustractthatisacontinuationofthelarynx;itdividesintotwomainbronchi,eachofwhichendsinalung,andallowsairtopass.Theinnermembraneofthetracheaiscoveredintinyhairscalledcilia,whichcatchparticlesofdustwhichwecanthenremovethroughcoughing.BronchiThetracheadi
5、videsintotwotubescalledbronchi,oneenteringtheleftandoneenteringtherightlung.Bronchibranchintosmallerandsmallertubesknownasbronchioles.Bronchiolesterminateingrape-likesacclustersknownasalveoli.Alveoliaresurroundedbyanetworkofthin-walledcapillaries.Bronchioles:Tertiarybronc
6、hicontinuetodivideandbecomebronchioles,verynarrowtubes.Thereisnocartilagewithinthebronchiolesandtheyleadtoalveolarsacs.Alveoli:Individualhollowcavitiescontainedwithinalveolarsacs(orducts).Alveolihaveverythinwallswhichpermittheexchangeofgasesoxygenandcarbondioxide.Theyares
7、urroundedbyanetworkofcapillaries,intowhichtheinspiredgasespass.Thereareapproximately3millionalveoliwithinanaverageadultlung.TheLowerRespiratoryTractsThelungstakeinoxygen,whichallcellsthroughoutthebodyneedtoliveandcarryouttheirnormalfunctions.Thelungsalsogetridofcarbondiox
8、ide,awasteproductofthebody'scells.Thelungsareapairofcone-shapedorgansmadeupofspongy,pinkish-gray
