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HumanAnatomy Unit2 DIGESTIVESYSTEM InAnatomyToday AbdominopelvicQuadrants AbdominopelvicRegions BodyCavities BodyCavities SerousMembranes • Asimplesquamousepitheliumanditsunderlyingconnective tissue – Producesaserousfluid – Lubricates,preventfrictionaldamage • Pericardialcavity – Visceralpericardium – Parietalpericardium • Pleuralcavity – Visceralpleura – Parietalpleura • Abdominalcavity – Visceralperitoneum – Parietalperitoneum ComponentsoftheDigestiveSystem Functions • Motility – – – – ingestion mastication deglutition peristalsis • Secretion – exocrine – endocrine • Digestion • Absorption Terminology • Ingestion • totakeinfood • Mastication • chewing(mechanicalbreakdownoffood) • Deglutition • swallowing • Digestion • chemicalbreakdownoffood • Absorption • passageofnutrientsfromthegitractlumentotheblood • Peristalsis • Wavesofsmoothmusclecontractiontopropelfood • Defecation • formationandexcretionofsolidwaste Mucosa • Absorptivelayer,largesurfacearea • 3majorcomponents – Mucosalepithelium • Columnarepithelium(stomach,intestines)orstratifiedsquamous • GastricPits,CryptsofLeiberkuhn,IntestinalCrypts – foldsinthemucosaofthesmallintestines,colon – sourceofnewepithelialcells – digestiveenzymes – Laminapropria • LooseCTofthemucosa,withcapillariesthatreceiveabsorbednutrients • lymphatictissue:capillariesandlymphaticnodulesinvolvedinabsorptionof fat • Peyer’sPatches:aggregatesoflymphnodes,significantprotectionagainst intestinalinfections – Muscularismucosa • athinlayerofsmoothmusclethatkeepsthefoldsofthemucosafolded Submucosa,MuscularisExterna, Serosa • Submucosa – tissue:denseirregularCT – Submucosalplexus • nervesupplytothemuscularismucosa • MuscularisExterna – mostlyadoublelayerofsmoothmuscle,propelsandmixesdigestive contents • circularlayer:thickinnerlayer,musclefibersdescribeacircle • longitudinallayer:thinouterlayer,musclefibersrunalongthelengthoftheGI tract – Myentericplexus:nervesupplytothemuscularisexterna • Serosa – looseCT+simplesquamousepithelium – outerwalloftheGItract EntericNervousSystem – Isthevisceralperitoneum MovementThroughtheDigestiveTube Mesentaries • Sheetsofserousmembranethatconnectthe parietalandvisceralperitoneum – Suspendsorgansinthespace – Providesarouteforbloodvessels,nerves,lymphatics • • • • • • Lesseromentum Greateromentum Mesenteryproper Mesocolon Transversemesocolon Sigmoidal mesocolon OralCavity TheTongue • • • • • Body Root Papillae Tastebuds Frenulum SalivaryGlands • Releasewater,lysozyme, digestiveenzymes,mucus – Salivaryamylase • Parotid – Pureserous – Parotidduct • Sublingual – Puremucus – Sublingualducts • numerous • Submandibular – Mixedserous/mucus – Submandibular ducts • numerous Teeth • • • • • • Neck Crown Gingivae Enamel Dentine Pulpcavity – Apicalforamen • Periodontalligaments • Cementum TypesofTeeth Pharynx • Passagewayforair, water,food • Divisions – Nasopharynx – Oropharynx – Laryngealpharynx Swallowing Esophagus • Function – movefoodtothestomach • Liningepithelium – stratifiedsquamous • Musclelayer – 1stthird • skeletalmuscle – 2ndthird • amixtureofskeletaland smoothmuscle – 3rdthird • smoothmuscle EsophagealGastricJuncture GrossAnatomyoftheStomach • Lessercurvature • Greatercurvature • Cardia – Cardiacorifice • Fundus • Body • Pylorus – Pyloricsphincter • Rugae LayersoftheStomach FunctionsoftheStomach • Functions – Foodstorage – Chemicaldigestion • Chiefcells • Parietalcells – Mechanicaldigestion • Churningby3layersofsmoothmuscle – Killsbacteria – MovesfoodtoSI – Hormonalregulationofdigestion • Gcells HistologyoftheStomach • Liningepithelium – simplecolumnar epithelium – Muconneckcells • Gastricglands – microscopicfolds, secretegastricjuice. • Gastricpits – openingsfromgastric glandstogastriclumen TheSmallIntestine • ~3meterslong • Function – Digestionandabsorption • • • • Duodenum Jejunum Ileum Supportofthesmall intestine – Mesentary proper IntestinalSurfaceArea • Plicaecircularis – macroscopicpermanentfolds(permanentuntil death) – Circularpleatslikeconduit • Villi – fingerlikeprojections • Microvilli – submicroscopicfoldsonapicalsurfaceof columnarcells – “brushborder” HistologicalOrganizationoftheSmall Intestine Serosa versusAdventitia HistologyoftheSmallIntestine • • • • Intestinalvilli Microvilli Gobletcells CryptsofLieberkühn RegionsoftheColon • Ascendingcolon – Rightcolicflexure • Transversecolon – Leftcolicflexure • Descendingcolon • Sigmoidcolon – Sigmoidflexure LargeIntestine • Cecum – Ilealpapilla – Iliocecalvalve – appendix • Thecolon Appendix:anextensionoflymphatic tissueneartheileocecaljunction – – – – – Thinwall Largerdiameter Haustra Taeniaecoli Fattyappendices TheRectum • • • • • Last15cm Analcanal Analcolumns Internalanalsphincter Externalanalsphincter HistologyofTheLargeIntestine • Lacksvilli • Abundantgobletcells • Intestinalcrypts – Deeper – Moregobletcells • Largelymphoidnodules • Taeniacoli – Reducedlongitudinal muscularislayer AccessoryGlandularDigestive Organs • Liver • Gallbladder • Pancreas AnatomyoftheLiver • Lobes – Left,right,caudate,quadrate • Ligaments – Falciformligament • Livertoanteriorbodywall – Coronaryligament • Livertodiaphragm – Ligamentumtereshepatis (alsocalledtheround ligament) • Falciformligamenttoumbilicus • Left,righthepaticducts LiverLobules • Functionalunitoftheliver • Hepatictriad – Hepaticartery – Hepaticportalvein – Bileduct • Bilecanaliculi • Hepatocytes – Hepaticplates(cords) • Kupffercells – macrophages • Centralvein • Sinusoids TheGallBladder • • • • • Fundus Body Neck Stores,concentratesbile Ducts – – – – Left,righthepaticducts Commonhepaticduct Cysticduct Commonbileduct • Hepatopancreaticsphincter – AmpullaofVater – SphincterofOddi ThePancreas • • • • Head Body Tail Pancreaticduct – SphincterofOddi • Accessorypancreatic duct – DuctofSantorini HistologyofthePancreas • Pancreaticacini – Exocrineglands – Pancreaticjuice • IsletsofLangerhans – Endocrineglands – Alphacells • glucagon – Betacells • insulin BloodFlow
