口腔、食道、胃功能-课件

GastrointestinalPhysiology

(Part2)GastrointestinalPhysiology(P1OutlinesPregastricdigestionMasticationSwallowingSecretionofsalivarySaliva：secretion，compositionandfunctionsNervousregulationofsalivarysecretionGastricdigestionGastricsecretionGastricjuice：source，compositionandfunctionsHClsecretion：cellularmechanismandregulationControlofgastricsecretionduringdigestiveperiodGastricmotilityReceptiverelaxation，toniccontractionandPeristalticcontractionGastricemptying：mechanismandcontrolOutlinesPregastricdigestion2胃前消化咀嚼Mastication(chewing)将大颗粒块状食物研磨成小块，增加唾液淀粉酶作用面积与唾液混合，形成食团刺激口腔内感受器，参与胃、小肠消化功能调节

胃前消化咀嚼Mastication(chewing)3PregastricdigestionPregastricdigestion4Pregastricdigestion吞咽Deglutition分期及特点UPregastricdigestion吞咽Deglutit5Pregastricdigestion蠕动Peristalsis蠕动的机械消化功能蠕动过程中平滑肌的收缩特征介导蠕动的主要是内在神经系统Pregastricdigestion蠕动Peristal6Pregastricdigestion食管下括约肌loweresophagealsphincter(LES)的功能未进食期间…吞咽时…Pregastricdigestion食管下括约肌low7Pregastricdigestion吞咽时介导LES张力下降的物质：NO和VIP（由迷走神经末梢释放）其它体液因素/NOAchPregastricdigestion吞咽时介导LES张8返流性食管炎Inhumans,commondisordersinvolvingtheesophagusincludeheartburnandgastroesophagealrefluxdisease(GERD).Inbothcases,thelowersphincterdoesnotcloseproperly,allowingacidfromthestomachtorefluxbackintotheesophagus,causesaburningsensationinthechestorthroat(heartburn)oradditionalsignssuchascoughingorasensationofchoking.返流性食管炎Inhumans,commondisord9Pregastricdigestion唾液腺腮腺下颌下腺舌下腺Pregastricdigestion唾液腺10Pregastricdigestion唾液来源：Secretedfromserousandmucouscellsofsalivaryglands理化特性：A97-99.5%water,低渗hypo-osmotic,pH6-7，containing电解质–Na+,K+,Cl–,PO42–,HCO3–唾液淀粉酶蛋白质–mucin,lysozyme,defensins,andIgA代谢产物–ureaanduricacidPregastricdigestion唾液11Pregastricdigestion导管上皮细胞：主动吸收Na+，被动吸收Cl-，主动分泌K+和HCO3-

分泌速率改变对唾液渗透压的影响分泌速率改变对唾液pH值的影响Pregastricdigestion导管上皮细胞：主动吸12Pregastricdigestion唾液的功能形成可以吞咽的食团开始对淀粉的化学性消化（唾液淀粉酶）杀菌和参与机体防御作用对牙齿的保护作用Pregastricdigestion唾液的功能13Pregastricdigestion唾液分泌的神经调节

主要由副交感神经调节交感神经兴奋时也能引起唾液分泌增加刺激和抑制唾液分泌的因素

Pregastricdigestion唾液分泌的神经调节14胃内消化胃的主要消化功能:接纳和暂时贮存胃内的机械性和化学性消化将食糜送入小肠（排空）分泌内因子，帮助vitaminB12在小肠吸收胃内消化胃的主要消化功能:15Gastricdigestion胃液的来源贲门腺：mucous幽门腺：mucous泌酸腺SurfaceEpithelium-insolublemucousNeckCells-solublemucousParietal(oroxyntic)Cells-HCl&IntrinsicFactorChiefCells-pepsinogen

Gastricdigestion胃液的来源贲门腺：mu16Gastricdigestion胃液的成分Salt,water,HCl,pepsin,intrinsicfactor,andmucus.（pH1.0-3.5,1.5-2.5L/Day）胃液中HCl有哪些生理功能?

分泌速率改变对胃液成分的影响pHK+--呕吐引起的低血钾症Gastricdigestion胃液的成分17TEMofrestingparietalcellfrompigletstomach,showingcanaliculus(C)surroundedbynumeroustubulovesicles(TV)andmitochondria.

Bar=1μmTEMofmaximallystimulatedparietalcell(piglet),showinggreatlyenlargedcanaliculiwithelongatedmicrovilli.

Remainingspacehasdenselypackedmitochondriaandveryfewtubulovesicles.

Bar=1μmTEMofrestingparietalcellf18口腔、食道、胃功能-课件19壁细胞分泌盐酸的机制细胞内H2O分解为H+和OH-，OH-与CO2反应生成HCO3-;碳酸酐酶（CA）催化这一过程HCO3-在基底膜与Cl-交换.HCO3-随后进入毛细血管，导致血液pH轻微升高(餐后碱潮，postprandialalkalinetide）Cl-和K+从管腔膜上的特异通道进入胃腔管腔膜上的质子泵（protonpump，H+-K+ATPase)主动将H+泵出细胞，同时交换一个K+进入细胞管腔内，H+与Cl-生成HCl壁细胞分泌盐酸的机制细胞内H2O分解为H+和OH-，O20Gastricdigestion质子泵抑制剂Protonpumpinhibitors,PPIs抑酸机制Drugshavebeendevelopedthatnon-competivelybindandinactivatetheATPase,resultinginstronginhibitionofacidsecretion.Omeprazole奥美拉唑isanacid-activatedprodrugthatbindscovalentlytotwocysteinesontheATPase,resultinginitsirreversibleinactivation..Otherinhibitors,includinglansoprazole兰索拉唑,esomeprazole艾美拉唑,rabeprazole雷贝拉唑andpantoprazole泮托拉唑havesimilarmodesofaction.PPIsGastricdigestion质子泵抑制剂Proton21盐酸分泌的调节内源性刺激物：Ach，组织胺和胃泌素通过壁细胞上的各自受体（M3-R，H2-R和G/CCK-B-R）刺激HCl分泌迷走神经末梢：AchG细胞：胃泌素（血液循环途径）ECL细胞：组织胺（旁分泌途径）ECL细胞是重要调节细胞，其上分布Ach和胃泌素受体G细胞释放胃泌素的调节因素对胃窦的机械牵张刺激和化学刺激促进G细胞分泌迷走神经兴奋末梢释放GRP激活GRP受体促进G细胞分泌来源于D细胞的生长抑素激活生长抑素受体抑制G细胞分泌迷走神经末梢释放Ach作用于D细胞上的受体抑制其分泌生长抑素，间接促进了G细胞分泌D细胞介导壁细胞HCl分泌的负反馈调节机制胃窦内H+浓度升高，刺激D细胞分泌生长抑素盐酸分泌的调节内源性刺激物：Ach，组织胺和胃泌素通过壁细胞22阿托品Atropine的抑酸机制：阻断M受体西米替丁cimetidine的抑酸机制：阻断H2受体SomeotherH2ReceptorAntagonists：ranitidine,famotidineandnizatidine

阿托品Atropine的抑酸机制：阻断M受体Someoth23口腔、食道、胃功能-课件24Gastricdigestion胃蛋白酶原和胃蛋白酶

胃蛋白酶原的激活HCl胃蛋白酶自身激活pHoptima1.8-3.5AchandHCl刺激主细胞分泌胃蛋白酶原内因子IntrinsicFactor结合VitaminB12，防止其被消化和破坏与VB12生成的复合物IF-VitB12是回肠吸收VB12的形式缺乏：恶性贫血perniciousanemia(PA)Gastricdigestion胃蛋白酶原和胃蛋白酶25Gastricdigestion粘液-碳酸氢盐屏障Mucus-bicarbonatebarrier物理屏障：厚(500μ)，凝胶状化学屏障：碳酸氢盐-pH梯度Gastricdigestion粘液-碳酸氢盐屏障Muc26GastricdigestionReviewquestionHowdoesthestomachprotectitselffromthegastricHCl?GastricbarrierTightjunctionsbetweentheepithelialcellsControlofHClsecretionTrophiceffectsbyGIhormonesGastricdigestionReviewquest27AcutegastritisGastriculcerAcutegastritisGastriculcer28Gastricdigestion消化期胃液分泌的调节Gastricdigestion消化期胃液分泌的调节29Gastricdigestion头期（神经调节）头部刺激因素：感觉器官刺激，高级中枢参与的调节反射支配壁细胞的迷走神经兴奋(ACh)支配G细胞的迷走神经兴奋（GRP）支配ECL的迷走细胞兴奋（GRP）支配D细胞的迷走神经兴奋（Ach）Gastricdigestion头期（神经调节）30Gastricdigestion胃期GastricPhase胃内的机械和化学刺激经短反射和长反射（迷走-迷走反射）作用于Parietalcells(ACh)Gcells(releasegastrin)ECLcells(releasehistamine)胃酸分泌的正反馈机制Gastricdigestion胃期GastricPh31Gastricdigestion肠期(pHabove3)

蛋白质消化产物（多肽）在十二指肠刺激G细胞食糜进入十二指肠机械刺激G细胞肠泌酸素enterooxyntin的作用Gastricdigestion肠期(pHabove32Gastricdigestion抑制胃酸分泌的因素：胃内：GastricpH<2--->gastricDcellsreleasesomatostatinwhichinhibitsgastrinrelease十二指肠：Acidinduodenum--->secretin&CCK--->inhibitsgastricsecretionandmotilityAcid,fats,hyper-osmoticsolutionsintheduodenum--->releaseofenterogastrones--->inhibitgastricmotilityandsecretionGastricInhibitoryPeptide(GIP)fromduodenum--->inhibitsparietalcellfunction

Distensionandchemicalstimulation

--->肠胃反射Entero-gastricreflex

Gastricdigestion抑制胃酸分泌的因素：33Gastricdigestion胃的运动胃的生理功能分区

EmptyingGastricdigestion胃的运动Emptying34Gastricdigestion紧张性收缩头端胃（近端胃）的容受性舒张神经反射，NO和VIP介导VagusNO,VIP[Entericnervoussystem]Gastricdigestion紧张性收缩VagusNO35口腔、食道、胃功能-课件36Gastricdigestion远端胃的蠕动Peristalticcontraction起源于胃中部（3次/min）向幽门方向推进，一波未平一波又起，蠕动波得以叠加、增强幽门附件蠕动波最强食糜数毫升被挤入十二指肠大部分返回胃窦进一步研磨和混合

Gastricdigestion远端胃的蠕动Perist37Gastricdigestion胃排空的概念促进胃排空的因素（反之，抑制）IntenseperistalticcontractionsDecreasedpylorictoneRelativelydecreasedduodenalmotility胃排空的速率由胃内因素和十二指肠内因素共同调节GastricfactorspromoteemptyingDuodenalfactorsinhibitstomachemptyingGastricdigestion胃排空的概念38Gastricdigestion神经和体液因素均参与胃排空速率的调节维持合适的胃排空速率的生理意义？？Gastricdigestion神经和体液因素均参与胃排39GastricdigestionMigratingmotorcomplexes(MMC)移行性复合运动arewavesofactivitywhichsweepthroughtheintestinesinaregularcycleduringfastingstate(originatesinthestomachroughlyevery75-120minutes).GastricdigestionMigratingmo40GastricdigestionThesemotorcomplexeshelptriggerperistalticwaveswhichfacilitatetransportationofindigestiblesubstancessuchasbone,fibe