呼吸系统vertebrate脊椎动物backbone脊柱bell

vertebrate脊椎动物backbonebellow风箱irritantbadmintoncourtnasal鼻的nasalcavity鼻腔paranasaladjsinusparanasalsinuslubricatingadj.pharynx咽throat咽喉nasopharynx鼻咽adenoid腺样体pharyngeal咽的tonsil扁桃体pharyngealtonsil咽扁桃体airpassageway气道oropharynx口咽palatine腭的，腭骨palatinetonsilhypopharynx下咽部，喉咽laryngopharynx喉咽hypopharyngeallarynxvocalcord

Alllivinganimalsmusttakeinoxygenandgetridofcarbondioxide.Inthevertebrates-animalswithbackbones-thatgettheiroxygenfromtheair,bothtasksareperformedbyspecialgasexchangeorganscalledlungs.Thelungsprovideaplacewhereoxygencanreachthebloodandcarbondioxidecanberemovedfromit.Theyareequippedwithtubesandabellowssystemfordrawinginairfromtheoutside,whilethepulmonaryveinsandarteriescirculatebloodthroughfrominside.Thelungsalsohaveacleaningsystemthattraps,ejects,ordestroysirritantsandotherharmfulsubstancesthattravelinwiththeair.Intheadulthumanthetotallungsurface,ifflattenedout,wouldbelargerthanabadmintoncourt,about83squaremeters.Airentersthebodythroughthenoseandpassesthroughthenasalcavity,whichislinedwithamucousmembraneandfinehairs(cilia)tohelpfilteroutforeignbodies,aswellastowarmandmoistentheair.Paranasalsinusesarehollow,air-containingspaceswithintheskullthatcommunicatewiththenasalcavity.They,too,haveamucousmembraneliningandfunctiontoprovidethelubricatingfluidmucus,aswellastolightenthebonesoftheskullandhelpproducesound.Afterpassingthroughthenasalcavity,theairnextreachesthepharynx(throat).Therearethreedivisionsofthepharynx.Thenasopharynxisthefistdivision,anditisnearesttothenasalcavities.Itcontainstheadenoids,whicharemassesoflymphatictissue.Theadenoids(alsoknownasthepharyngealtonsils)aremoreprominentinchildren,andifenlarged,theycanobstructairpassageways.Belowthenasopharynxandclosertothemouthistheseconddivisionofthepharynx,theoropharynx.Thepalatinetonsils,tworoundedmassedoflymphatictissue,arelocatedintheoropharynx.Thethirddivisionofthepharynxisthehypopharynx(alsocalledthelaryngopharynx).Itisinthehypopharyngealregionthatthepaharynx,servingasacommonpassagewayforfoodfromthemouthandairfromthenose,dividesintotwobranches,thelarynx(voicebox)andtheesophagus.Theesophagusleadsintothestomachandcarriesfoodtobedigested.Thelarynxcontainsthevocalcordsandissurroundedbypiecesofcartilageforsupport.Soundsareproducedasairisexpelledpastthevocalcords,andthecordsvibrate.Thetensionofthevocalcordsdeterminesthehighorlowpitchofthevoice.Sincefoodenteringfromthemouthandairenteringfromdeterrentflap皮瓣tongue舌epiglottismediastinum中隔膜，纵隔bronchusplbronchi)管bronchial支气管的bronchiole细支气管alveolus(pl.alveoli)肺泡epitheliumerythrocytedouble-foled双层折叠的parietal壁的，壁侧的visceralthoraxlobe肺叶uppermost最上的hilum门(肺门)midline正中线collarbone锁骨diaphragmpartitioninhalation吸入inspiration

nosemixinthepharynx,whatpreventsthepassingoffoodordrinkintothelarynxandrespiratorysystemafterithasbeenswallowed?Evenwithasmallquantityofsolidorliquidmatterfindingitswayintotheairpassages,breathingcouldbeseriouslyblocked.Aspecialdeterrenttothiseventisprovidedforbyaflapofcartilageattachedtotherootorthetonguethatactslikealidoverthelarynx.Thisflapofcartilageiscalledepiglottis.Theepiglottisliesovertheentrancetothelarynx.Intheactofswallowing,whenfoodandliquidmovethroughthethroat,theepiglottisclosesoffthelarynx,sothatthesethingscannotenter.Onitswaytothelungs,airpassesfromthelarynxtothetrachea(windpipe),averticaltubeofabout21to27millimetresininnerdiameterandabout10to16centimetresinlength.Thetracheaiskeptopenby15-20incompleteC-shapedringsofcartilageseparatedbyfibrousconnectivetissuethatstiffensthefrontandsidesofthetube.Intheregionofthemediastinum,thetracheadividesintotwobranchescalledbronchi.Eachbronchusleadstoaseparatelunganddividesandsubdividesintosmallerandfinertubes,somewhatlikethebranchesofatree.Thesmallestofthebronchialbranchesarecalledbronchioles.Attheendofthebronchiolesareclustersofairsacscalledalveoli.Eachalveolusismadeofaone-celllayerofepithelium.Theverythinwallallowsfortheexchangeofgasesbetweenthealveolusandthecapillariesthatsurroundandcomeinclosecontactwithit.Thebloodthatflowsthroughthecapillariesacceptstheoxygenfromthealveolusanddepositscarbondioxideintothealveolustobeexhaled.Oxygeniscombinedwithahemoglobininerythrocytesandcarriedtoallpartsofthebody.Eachlungisenvelopedinadouble-foldedmembranecalledthepleura.Theoutlayerofthepleura,nearesttheribs,istheparietalpleura,andtheinnerlayer,closesttothelung,isthevisceralpleura.Thepleuraismoistenedwithaseroussecretionthatfacilitatesthemovementsofthelungswithinthethorax.Thetwolungsarenotquitemirrorimagesofeachother.Therightlung,whichistheslightlylargerofthetwo,isdividedintothreelobes,ordivisions,andtheleftlungisdividedintotwolobes.Itispossibleforonelobeofthelungtoberemovedwithoutdamagetotherest,whichcancontinuetofunctionnormally.Theuppermostpartofthelungiscalledtheapex,andthelowerareaisthebase.Thehilumofexhalation呼出expiration呼出，呼气phrenic横膈膜的intercostals肋间的compliance顺应性brainstem脑干rhythmcarbonicacidacidity酸度alkalinity碱度ventilation通气hyperventilationalkalinealkalosishypoventilationacidosispollutantproject投射wavelike波浪状的irritating刺激性的stagnant停滞的sputum痰constriction收缩tornado旋风；龙卷风macrophage巨噬细胞

thelungisthemidlineregionwherebloodvessels,nerves,andbronchialtubesenterandexittheorgan.Thelungsextendfromthecollarbonetothediaphragminthethoraciccavity.Thediaphragmisamuscularpartitionthatseparatesthethoracicfromtheabdominalcavityandaidsintheprocessofbreathing.Thediaphragmcontractsanddescendswitheachinhalation(inspiration).Thedownwardmovementofthediaphragmenlargestheareainthethoraciccavityandreducestheinternalairpressure,sothatairflowsintothelungstoequalizethepressure.Whenthelungsarefull,thediaphragmrelaxesandelevates,makingtheareainthethoraciccavitysmaller,andthusincreasingtheairpressureinthethorax.Airthenisexpelledoutofthelungstoequalizethepressure;thisiscalledexhalation(expiration).Otherpartsarealsoinvolvedintheprocess.Thecycleofrespirationreallybeginswhenthephrenicnervestimulatesthediaphragmtocontractandflatten.Also,theintercostalsmusclesbetweentheribsaidininspirationbypullingtheribsupandout.Themeasureofhoweasilythelungsexpandunderpressureiscompliance.Breathingisregulatedunconsciouslybycenterinthebrainstem.Thesecentersadjusttherateandrhythmofbreathingaccordingtochangesinthecompositionoftheblood,especiallytheconcentrationofcarbondioxide.GasTransport.Oxygeniscarriedinthebloodboundtohemoglobininredbloodcells.Theoxygenisreleasedtothecellsasneeded.Carbondioxideiscarriedinseveralways,butismostlyconvertedtoanacidcalledcarbonicacid.Theamountofcarbondioxidethatisexhaledisimportantinregulatingtheacidityoralkalinityoftheblood.Iftoomuchcarbondioxideisexhaledbyhyperventilation,bodyfluidstendtobecomemorealkaline,aconditiontermedalkalosis.Iftoolittlecarbondioxideisexhaledasaresultofhypoventilation,bodyfluidstendtobecomemoreacid,aconditiontermedacidosis.Thecleanings