消化系統(tǒng) 英文版

DigestiveSystem編輯pptThedigestivesystemisresponsibleforbreakingdownfood,absorbingnutrientsfromthefood,andriddingthebodyofwasteproductsfromthefood.Itisroughlyninemeterslongandbeginsatthemouthandendsattheanus.編輯pptThedigestivesystemconsistsofthe:thealimentarytractmouth,pharynx,esophagus,stomach,smallandlargeintestines,rectumandanustheaccessoryorganssalivaryglands,liver,gallbladderandpancreas

編輯pptThemouth,ororalcavity,isthefirstpartofthedigestivetract.Itisadaptedtoreceivefoodbyingestion,breakitintosmallparticlesbymastication,andmixitwithsaliva.Thelips,cheeks,andpalateformtheboundaries.Theoralcavitycontainstheteethandtongueandreceivesthesecretionsfromthesalivaryglands.Kidshave20teeth,butbythetimetheyarefullygrown,theyshouldhave32teeth(somepeopledohaveless!).Theesophagusisthesecondsteptodigestionandcloselyfollowstheoralcavity–onceswallowinghasinitiated.theAlimentaryTract編輯pptThestomachisdividedintothefundic,cardiac,body,andpyloricregions.Thestomachhasthreelayersofmuscle:anouterlongitudinallayer,amiddlecircularlayer,andaninnerobliquelayer.Theinnerliningconsistsoffourlayers:theserosa,themuscularis,thesubmucosa,andthemucosa.Themucosaisdenselypackedwithgastricglands,whichcontaincellsthatproducedigestiveenzymes,hydrochloricacid,andmucus.Thestomachisamulti-functionalorgan,itstoresfood,breaksitdownandthenemptiesitintothesmallintestine.

編輯pptThesmallintestineconsistsofthreesections.

duodenum,jejunumandileumwhichattachestothefirstportionofthelargeintestine.Functiondigestion,andabsorption.Thesmallintestinefinishestheprocessofdigestion,absorbsthenutrients,andpassestheresidueontothelargeintestine.Theliver,gallbladder,andpancreasareaccessoryorgansofthedigestivesystemthatarecloselyassociatedwiththesmallintestine.編輯pptThelargeintestineismadeupofthreeportions:theascending,transverseanddescendingcolon.Itistheportionofthedigestivesystemmostresponsibleforabsorptionofwaterfromtheindigestibleresidueoffood.Theileocecalvalveoftheileum(smallintestine)passesmaterialintothelargeintestineatthececum.Materialpassesthroughtheascending,transverse,descendingandsigmoidportionsofthecolon,andfinallyintotherectum.Fromtherectumandanus,thewasteisexpelledfromthebody.編輯pptThreepairsofmajorsalivaryglands(parotid,submandibular,andsublingualglands)Salivacontainswater,mucusandenzymeamylase.FunctionsIthasacleaningactionontheteeth.Itmoistensandlubricatesfoodduringmasticationandswallowing.Itdissolvescertainmoleculessothatfoodcanbetasted.Itbeginsthechemicaldigestionofstarchesthroughtheactionofamylase,whichbreaksdownpolysaccharidesintodisaccharides.theAccessoryOrgans

編輯pptLiveristhelargestglandinthebody.Onthesurface,theliverisdividedintotwomajorlobesandtwosmallerlobes.Itoverliesandalmostcompletelycoversthestomach.Functionssecretionsynthesisofbilesaltssynthesisofplasmaproteinstoragedetoxificationexcretioncarbohydratemetabolismlipidmetabolismproteinmetabolismfiltering編輯pptThegallbladderisapear-shapedsacthatisattachedtothevisceralsurfaceoftheliverbythecysticduct.Theprincipalfunctionofthegallbladderistoserveasastoragereservoirforbile.Bilesaltsactasemulsifyingagentsinthedigestionandabsorptionoffats.Itissecretedfromtheintestineandspecificallytheduodenum.編輯pptThepancreasislocatedinthebackoftheabdomen,behindthestomach.Thepancreasmakespancreaticjuicesandhormones,includinginsulin.Pancreaticjuice