消化系统 英文版ppt课件

.,DigestiveSystem,.,Thedigestivesystemisresponsibleforbreakingdownfood,absorbingnutrientsfromthefood,andriddingthebodyofwasteproductsfromthefood.Itisroughlyninemeterslongandbeginsatthemouthandendsattheanus.,.,Thedigestivesystemconsistsofthe:thealimentarytractmouth,pharynx,esophagus,stomach,smallandlargeintestines,rectumandanustheaccessoryorganssalivaryglands,liver,gallbladderandpancreas,.,Themouth,ororalcavity,isthefirstpartofthedigestivetract.Itisadaptedtoreceivefoodbyingestion,breakitintosmallparticlesbymastication,andmixitwithsaliva.Thelips,cheeks,andpalateformtheboundaries.Theoralcavitycontainstheteethandtongueandreceivesthesecretionsfromthesalivaryglands.Kidshave20teeth,butbythetimetheyarefullygrown,theyshouldhave32teeth(somepeopledohaveless!).Theesophagusisthesecondsteptodigestionandcloselyfollowstheoralcavityonceswallowinghasinitiated.,theAlimentaryTract,.,Thestomachisdividedintothefundic,cardiac,body,andpyloricregions.Thestomachhasthreelayersofmuscle:anouterlongitudinallayer,amiddlecircularlayer,andaninnerobliquelayer.Theinnerliningconsistsoffourlayers:theserosa,themuscularis,thesubmucosa,andthemucosa.Themucosaisdenselypackedwithgastricglands,whichcontaincellsthatproducedigestiveenzymes,hydrochloricacid,andmucus.Thestomachisamulti-functionalorgan,itstoresfood,breaksitdownandthenemptiesitintothesmallintestine.,.,Thesmallintestineconsistsofthreesections.duodenum,jejunumandileumwhichattachestothefirstportionofthelargeintestine.Functiondigestion,andabsorption.Thesmallintestinefinishestheprocessofdigestion,absorbsthenutrients,andpassestheresidueontothelargeintestine.,Theliver,gallbladder,andpancreasareaccessoryorgansofthedigestivesystemthatarecloselyassociatedwiththesmallintestine.,.,Thelargeintestineismadeupofthreeportions:theascending,transverseanddescendingcolon.Itistheportionofthedigestivesystemmostresponsibleforabsorptionofwaterfromtheindigestibleresidueoffood.Theileocecalvalveoftheileum(smallintestine)passesmaterialintothelargeintestineatthececum.Materialpassesthroughtheascending,transverse,descendingandsigmoidportionsofthecolon,andfinallyintotherectum.Fromtherectumandanus,thewasteisexpelledfromthebody.,.,Threepairsofmajorsalivaryglands(parotid,submandibular,andsublingualglands)Salivacontainswater,mucusandenzymeamylase.FunctionsIthasacleaningactionontheteeth.Itmoistensandlubricatesfoodduringmasticationandswallowing.Itdissolvescertainmoleculessothatfoodcanbetasted.Itbeginsthechemicaldigestionofstarchesthroughtheactionofamylase,whichbreaksdownpolysaccharidesintodisaccharides.,theAccessoryOrgans,.,Liveristhelargestglandinthebody.Onthesurface,theliverisdividedintotwomajorlobesandtwosmallerlobes.Itoverliesandalmostcompletelycoversthestomach.,Functionssecretionsynthesisofbilesaltssynthesisofplasmaproteinstoragedetoxificationexcretioncarbohydratemetabolismlipidmetabolismproteinmetabolismfiltering,.,Thegallbladderisapear-shapedsacthatisattachedtothevisceralsurfaceoftheliverbythecysticduct.Theprincipalfunctionofthegallbladderistoserveasastoragereservoirforbile.Bilesaltsactasemulsifyingagentsinthedigestionandabsorptionoffats.Itissecretedfromtheintestineandspecificallytheduodenum.,.,Thepancreasislocatedinthebackoftheabdomen,behindthestomach.,Thepancreasmakespancreaticjuicesandhormones,includinginsulin.Pancreat