关于消化系统的英文ppt课件

TheDigestiveSystem(alsocalledthegastrointestinaloralimentarycanal),1,Theprimaryfunctions,IngestionDigestionAbsorptionElimination,Introduction,Anatomically,thedigestivesystemconsistofa30-footlong,mucousmembrane-linedtubebeginningwithmouthandendingwiththeanus,2,Thedigestivesystem,MouthPharynxEsophagusStomachSmallintestineLargeintestineLiverGallbladderPancreas,Accessoryorgansofthedigestivesystem,3,4,Theoralcavity,TheteethThetongueThepalate,Chewingandswallowing,Theteethareusedtocut,tearandcrushfoodintosmallerpieces.Eachtoothconsistsofpulp,cementumandenamel.Theteethareclassifiedincisors,cuspidsandmolars.Thetonguemanipulatesfoodinthemouthduringmasticationanddeglutition.Thepalatethehardplateandthesoftplate(theuvulahangingfromthesoftplate),5,6,7,Thepharynxorthroat,isalongmusculartubethatservesasapassagewayforfoodfromthemouthtotheesophagusandasapasswayforairfromnosetothewindpipe.Theesophagusisalongmusculartubeextendingfromthepharynxtothestomach.Foodispropelledbyrhythmiccontractionsofmusclesinthewalloftheesophagus.Thisprocessiscalledperistalsis.,8,ThestomachItiscomposedofanupperportioncalledfundus,amiddlesectionknownasthebodyandalowerportion,calledtheantrum.Thecardiacsphincterrelaxesandcontractstomovefoodfromtheesophagusintothestomach,whereasthepyloricsphincterallowsfoodtoleavethestomachwhenitsufficientlydigested.Asthestomachfills,therugaeunfolded,exposingthedigestiveglandsandstimulatingthemtosecretdigestiveenzymesandhydrochloricacid.Thesesubstanceshelptransformfoodpresenttoasemifluidsubstance.,9,10,Thesmallintestineistheregionofthegutwherenearlyallofthechemicaldigestionofthenutritioncomponentsoffoodtakeplace.Itdividedinto3sections:1)theduodenum2)thejejunum3)theileumInthewalloftheentiresmallintestinearemillionsofvilli.Itisthroughthecapillariesinthevillithatcompletelydigestednutrientspassintothebloodstreamandlymphvessels.,11,Thelargeintestineisdividedinto4parts:cecum,colon,sigmoidcolon,andrectum.,Thececumisconnectedtothesmallintestinebytheileocecalvalve.Thecolonhas3divisions:theascendingcolon,thetransversecolon,thesigmoidcolon.Asfluidwastefromthesmallintestinepassthroughvarioussectionsofthecolon,waterisreabsorbedintobody.Therectumservesasareservoirforfeces.,12,13,Theliver:locatedintheupperrightquadrantofabdomen,producesbile.Besidesproducingbile,ithasseveralothervitalfunctions.Itmanufacturesbloodproteins,destorysolderythrocytesandreleasesbilirubin,removespoisons(detoxification）fromtheblood,storesandreleasesglycogenneededbythebody.,14,15,Thegallbladder：apear-shapedsacbehindthelowerportionoftheliver,storesbile,whichiscontinuouslysecretedbythehepaticcellsbetweenmeals.,16,17,Thepancreas:behindthestomach,manufacturesdigestivejuicecont