Ducts of Pancreas No striated ducts Intercalated ducts = intralobular ducts Intercalated ducts drain...

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Transcript of Ducts of Pancreas No striated ducts Intercalated ducts = intralobular ducts Intercalated ducts drain...

  • Ducts of PancreasNo striated ductsIntercalated ducts = intralobular ductsIntercalated ducts drain directly into interlobular ducts simple squamous or low columnar epitheliumMain pancreatic ducts (Wirsung and Santorini) simple columnar epithelium

  • Pancreatic Juice SecretionSecretin Secreted in response to HClProduces HCO3-rich secretion to neutralize acidic chyme (pancreatic enzymes function at optimal neutral pH)Cholecystokinin (CCK)In response to the entry of proteins and fatsEnzyme-rich fluid which act mainly on extrusion of zymogen granules

  • GallbladderHollow, pear-shaped organ attached to the lower surface of the liverLies in gallbladder fossaCan store 30-50 mL of bile

  • GallbladderFundusBody NeckCystic duct

  • GallbladderMain functions:Stores bileConcentrates bile (water absorption) Releases bile when necessary into the digestive tractBile fat emulsifier

  • Gallbladder WallMucosa:Have anastomosing folds, no villusSimple columnar epithelium without goblet cellsLamina propriaSmooth muscle layer stimulated by CCKPerimuscular connective tissue layer Serosa

  • Extrahepatic Bile PassagesHepatic ductsCommon hepatic ductCystic ductCommon bile duct

    Simple columnar epithelium

  • Important StructuresAmpulla of Vater (hepatopancreatic ampulla)Formed by union of pancreatic duct and CBDSphincter of Oddi Muscular valve that controls the flow of digestive juices (bile and pancreatic juice) through the ampulla of VaterMajor and minor duodenal papillaOpenings into the duodenum

  • LiverLargest gland of body (approx. 1.5 kg)Right upper quadrant, under diaphragm

  • LiverFunctions:Produces bile: hepatic ducts gallbladderSynthesis: plasma proteins, hormonesCarbohydrate storage: glycogenDetoxification and excretion of endogenous and exogenous toxic substances

  • LiverFunctions:Eliminates particulate materials from blood (phagocytosis)Processes dietary amino acids, carbohydrates, lipids and vitamins before they are released into general circulation

  • Glissons CapsuleThin fibroelastic capsule enclosing liverCovered with mesothelium

  • Blood VesselsPortal veinNutrient-rich blood from GIT liverHepatic arterySupplies liver pareynchyma with arterial blood

    Enter through porta hepatis

  • Portal TriadDistinctive arrangement in a hepatic lobuleConsists of:Hepatic arteryHepatic portal veinBile duct

  • Portal AreaInterlobular connective tissue + structures found in it (portal triad, lymphatic vessels, nerves)

  • Liver Architecture

    ShapeModelHepatic (classical) lobulePolygonalAnatomicalPortal lobuleTriangular (centered around portal triad)Exocrine fxn (bile secretion)Hepatic acinusElliptical or diamond-shaped

    Zone I (periportal)Zone II (transition zone)Zone III (centrilobular)Blood flow and metabolic

  • Liver CellsHepatocytesKupffer Cells

  • Hepatocytes80 % of cell population of liberPerform practically all metabolic and secretory functionsPolygonal cells arranged in layer (hepatic plates) which anastomose with each other or with sinusoidsNuclei: 1 or 2, round, prominent nucleoliCytoplasm: grainy, eosinophilic with many organelles

  • Kupffer CellsFixed macrophagesRemove old red blood cells from circulation and recycle their iron contentStellate shape (protoplasmic processes)Form the wall of hepatic sinusoids along with endothelial cellsNuclei: pale, vesicular

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