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ID:62075738
大小:1.03 MB
页数:41页
时间:2021-04-14
《最新The Digestive System - Winston-SalemForsyth County Schools:消化系统-温斯顿salemforsyth县学校-药学医学精品资料.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、最新TheDigestiveSystem-Winston-SalemForsythCountySchools:消化系统-温斯顿salemforsyth县学校-药学医学精品资料IntroductionThedigestivesystemisusedforbreakingdownfoodintonutrientswhichthenpassintothecirculatorysystemandaretakentowheretheyareneededinthebody.IntroductionThereare
2、fourstagestofoodprocessing:Ingestion:takinginfoodDigestion:breakingdownfoodintonutrientsAbsorption:takinginnutrientsbycellsEgestion:removinganyleftoverwastesTheHumanDigestiveSystemToenterthestomach,thebolusmustpassthroughtheloweresophagealsphincter,atig
3、htmusclethatkeepsstomachacidoutoftheesophagus.TheHumanDigestiveSystemThestomachhasfoldscalledrugaeandisabigmuscularpouchwhichchurnsthebolus(PhysicalDigestion)andmixesitwithgastricjuice,amixtureofstomachacid,mucusandenzymes.TheHumanDigestiveSystemTheacid
4、killsoffanyinvadingbacteriaorviruses.Theenzymeshelpbreakdownproteinsandlipids.ChemicalDigestion.Themucusprotectstheliningofthestomachfrombeingeatenawaybytheacid.TheHumanDigestiveSystemThestomachdoesdosomeabsorptiontoo.Somemedicines(i.e.aspirin),waterand
5、alcoholareallabsorbedthroughthestomach.Thedigestedbolusisnowcalledchymeanditleavesthestomachbypassingthroughthepyloricsphincter.TheHumanDigestiveSystemChymeisnowinthesmallintestine.Themajorityofabsorptionoccurshere.Theliverandpancreashelpthesmallintesti
6、netomaximizeabsorption.Thesmallintestineisbrokendownintothreeparts:TheHumanDigestiveSystemDuodenumBile,producedintheliverbutstoredinthegallbladder,entersthroughthebileduct.Itbreaksdownfats.Thepancreassecretespancreaticjuicetoreducetheacidityofthechyme.T
7、heHumanDigestiveSystemJejunumThejejunumiswherethemajorityofabsorptiontakesplace.Ithastinyfingerlikeprojectionscalledvilliliningit,whichincreasethesurfaceareaforabsorbingnutrients.TheHumanDigestiveSystemEachvilliitselfhastinyfingerlikeprojectionscalledmi
8、crovilli,whichfurtherincreasethesurfaceareaforabsorption.TheHumanDigestiveSystemIleumThelastportionofthesmallintestineistheileum,whichhasfewervilliandbasicallycompactstheleftoverstopassthroughthecaecumintothelargeintestine.TheHum
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