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ID:62067971
大小:3.86 MB
页数:60页
时间:2021-04-14
《最新Digestive System - University of Washington:消化系统-华盛顿大学教学讲义PPT.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、DigestiveSystem-UniversityofWashington:消化系统-华盛顿大学DigestiveSystemFunctionAcquiresnutrientsfromenvironmentAnabolismUsesrawmaterialstosynthesizeessentialcompoundsCatabolismDecomposessubstancestoprovideenergycellsneedtofunctionDigestive(GI)TractHistological
2、StructureoftheDigestive(GI)TractMovementofDigestiveMaterialsBymuscularlayersofdigestivetractConsistofvisceralsmoothmuscleAlongdigestivetract:Hasrhythmiccyclesofactivities(PERISTALSIS)ConsistsofwavesofmuscularcontractionsMoveabolusalongthelengthofthetrac
3、tControlledbypacesettercellsSurroundingthelumenofthetractCellsundergospontaneousdepolarizationTriggeringwaveofcontractionthroughentiremuscularsheetPeristalsisFunctionsofOralCavitySensoryanalysisOfmaterialbeforeswallowingMechanicalprocessingThroughaction
4、softeeth,tongue,andpalatalsurfacesLubricationMixingwithmucusandsalivaryglandsecretionsLimiteddigestionOfcarbohydratesandlipidsEsophagusAhollowmusculartubeAbout25cm(10in.)longand2cm(0.80in.)wideConveyssolidfoodandliquidstothestomachBeginsposteriortocrico
5、idcartilageIsinnervatedbyfibersfromtheesophagealplexusStomachFunctionMajorFunctionsoftheStomachStorageofingestedfoodMechanicalbreakdownofingestedfoodDisruptionofchemicalbondsinfoodmaterialbyacidandenzymesProductionofintrinsicfactor,aglycoproteinrequired
6、forabsorptionofvitaminB12insmallintestineGastricAnatomyDigestionintheStomachStomachperformspreliminarydigestionofproteinsbypepsinSomedigestionofcarbohydrates(bysalivaryamylase)Lipids(bylinguallipase)StomachcontentsBecomemorefluidpHapproaches2.0Pepsinact
7、ivityincreasesProteindisassemblybeginsAlthoughdigestionoccursinthestomach,nutrientsarenotabsorbedthereSmallIntestine90%ofabsorptionoccursinthesmallintestineSmallIntestineTheDuodenumThesegmentofsmallintestineclosesttostomach25cm(10in.)long“Mixingbowl”tha
8、treceiveschymefromstomachanddigestivesecretionsfrompancreasandliverFunctionsoftheduodenumToreceivechymefromstomachToneutralizeacidsbeforetheycandamagetheabsorptivesurfacesofthesmallintestineSmallIntestineTheJejunumIsthemiddlesegm
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