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1、Digestive SystemDigestive SystemDigestiveGlandsComponentsdigestiveglandsfoundinthewallofdigestivetractaccessorydigestiveglands:salivaryglands/pancreas/liverGeneralstructure*Parenchyma(functionalportionofanorgan,asdistinguishedfromthesupportingtissue):acini/glandcellsduct*Stroma(unfunctionalportionof
2、anorgan):capsule,CTinside.Salivaryglands*Parotid*SubmandibularG.*SublingualG.Threetypesofacini*serous*mucous*seromucousFunction:*moistening food*carbohydrate digestion*Secrete IgAPancreaspositionedretroperitoneallyontheposteriorwalloftheabdominalcavityatthelevelofthesecondandthirdlumbarvertebrae.nod
3、istinctcapsule,butiscoveredbyathinlayerofLCTbothanexocrine&endocrinegland.*exocrinepart:produces pancreatic juice*endocrinepart:produce hormonesComponentsoftheexocrinepancreasconsistsofserousglandsacinifilledwithacidophiliczymogengranulesintercalatedductextendsintothecentreoftheacini,whichislinedbyc
4、entroacinar cellsductsystem:intercalated ducts(low columnar or cuboidal epith.)Interlobular ducts(columnar epith.)Main pancreatic ducts(tall columanr epth.)major duodenal papillaFunctionofpancreaticjuice:*Trypsin,chymotrypsin&carboxypeptidasehydrolyseproteins;*ribonuclease&deoxyribonucleasesplitnucl
5、eicacids;*amylasehydrolysesstarch&glycogen*lipase hydrolysestriglyceridesintofattyacidsandmonoglycerides*cholesterol esterasebreaksdowncholesterolestersintocholesterolandafattyacid.ComponentsoftheEndocrine*IslandsofLangerhansscatteredthroughouttheexocrinepancreas.*Vascularization(manyfenestratedcap.
6、)ismoreextensivethanthatoftheexocrineacini.*ThreedifferenttypespresentA-cells(20%):glucagonproducerB-cells(75%):insulinproducerD-cells(5%):somatostatinproducerLiver*largestgland(2%ofbodyweightinadult).*receivesbothvenous&arterialbloodthroughtheportalV.(75%)&hepaticA(25%),respectively.*CTofcapsuleext
7、endedintotheparenchyma,forming“classical”liver loblules(basicstructureunits).*functionsasanexocrinegland(secretingbile).Structuresofliverlobules*six-sidedprismwithacentralV.atitscentre*delimitedbyinterlobularCT*portal triadsinthecorneroflobules(portalarea)*anastomosingplatesofhepaticcellsextendedrad
8、iallyfromthecentralV.*sinusoidsformbetweenhepaticplatesPortalareas*definition:a area found in the angles where adjacent hepatic lobules meet.*components:CT.+portaltriadinterlobular Ainterlobular Vinterlobular bile ductSinusoids*dialatedanastomosingvenulesbetweenthehepaticplates*bloodpathway:peripher
9、ycentralv.*Kupffer cellslinedinthewallofsinusoids*EM:significantgapsnumerousfenestrationincomplete basal laminaHepatocytes*makeupabout80%ofthecellsintheliver.*typicallylargepolyhedralcellswithlargeroundcentrallylocatednuclei.*abundanceoforganellesrelatedtothefunctionsMitochondria:energyprovidingRER:
10、proteinsynthesisSER:bileformation/metabolismoflipidsandhormones/detoxification.Lysosome:replacementanddefenceMicrobody:detoxification.Inclusions:glcogenparticles,lipiddropletsandpigments.Hepatocytefunction*Producebile*mediatecarbohydratereservesglycogen is degraded to glucose under regulation of hor
11、mones*Bloodlipidmetabolism*Synthesisofplasmaproteinsalbumin:majorplasmaproteinfibrinogenthrombinclotting factor IIIBileCanaliculiDefinition:tubularspacelimitedbyplasmamembraneoftwoadjacenthepatopcytes.Structure:LM:network-likestructuresareseenbysilverimpregnationEM:*plasmamembraneofadjacenthepatocyt
12、esformthewallofbilecanaliculi*tightjunctionsformsealsBliecanaliculistainedbysilverimpregnationPerisinusoidalsapce(spaceofDisse)aspacebetweentheendothelium&hepatocytebevisibleunderEMoccupiedbynumerousmicrovilliofhepatocytesfilledwithplasmafat-storingcells(storingfat&vitaminA)asiteforexchangebetweenth
13、eblood&hepatocytes.*celljunctionsurface*Perisinusoidalsurface:facetoperisinusoidalspace*bilecanalicularsurface:faceintothebile canaliculusInterlobuleA.&V.ThreetypesoffunctionalsurfaceinhepatocyteHepatic Blood SupplyHepatic Blood SupplyPortalVinterlobularVHepaticAinterlobularAsublobularVsinusoidscent
14、ralVhepaticVInferiorvenacava(75%)(25%)Bilecanaliculiperiperalbileductules(Herings)interlobularbileductLeft&righthepaticductsCommonhepaticductCommonbileductDuodenumpapillaCysticductGallbladderBiliary PassagesBiliary PassagesClassificationofLobules1.Classic lobule:2.Ahexagonalstructurewiththecentralveinatitscenter;atthesixcornersofthelubulearehepatictriads.2.Portal lobule:Atriangularstructurewiththeportalareaatitscenter.Threecentralveinsarefoundattheperipheralboundarypoints.3.Liver acinus:Anelongatediamond-shapedlobule;acentralveinisattheendsofeachofthetwoelongatedpointsofthediamond.