Liver pancreas

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  • 1.State University of Medicine and Pharmacy Nicolae TestemitanuLIVERGALL BLADDERPANCREASDepartment of Histology, Cytology and EmbryologyTatiana Globa

2. The Liver Largest gland of the body Two principal lobes: right and left Right lobe further subdivided: Quadrate lobe and caudate lobe Is surrounded by a capsule of connective tissue(Glissons capsule). 3. Functions of the Liver Digestive and Metabolic Functions synthesisand secretion of bile storage of glycogen and lipid reserves maintaining normal blood glucose, aminoacid and fatty acid concentrations synthesis and release of cholesterol boundto transport proteins inactivation of toxins storage of iron reserves storage of fat-soluble vitamins 4. Functions of the LiverNon-Digestive Functions synthesisof plasma proteins synthesis of clotting factors synthesis of the inactive angiotensinogen phagocytosis of damaged red blood cells storage of blood breakdown of circulating hormones (insulinand epinephrine) and immunoglobulins inactivation of lipid-soluble drugs 5. The morpho-functional unit ofthe liver classical liver lobule portal lobule liver acinus 6. LIVER LOBULE Hexagonal-shaped liver lobule (classical lobule) is the traditional description of the liver parenchyma organization Composed of hepatocyte (liver cell) plates(cords) radiating outward from a central vein Between the plates of hepatocytes there are sinusoids Has a central vein Portal triads are found at each of the six corners of each liver lobule 7. Sublobular veinDistributing veinCentral veinPlates of hepatocytes 8. PORTAL TRIADSPortal triads (also called portal areas or portalcanals) are located at the corners of liver lobules.Each portal area contains three (hence the termportal triad) more-or-less conspicuous tubularstructures all wrapped together in connectivetissue. a branch of the bile duct a branch of the portal vein - interlobular vein a branch of the hepatic artery - interlobularartery 9. Hepatocytes are cuboidal cells with one or two large euchromatic nuclei and with abundant, grainy cytoplasm that stains well with both acid and basic dyes (reflecting the abundance of various cellular constituents). they may accumulate abundant lipofuscin (yellow- brown "wear-and-tear" pigment), especially with advancing age. a typical hepatocyte has two surfaces with microvilli 10. Hepatocyte ultrastructure all cytoplasmicorganelles arevery welldeveloped cell membranefacing a bilecanaliculusand theperisinusoidalspace formsmicrovilli 11. Hepatocytes are located in flat irregular plates (cords) that arearranged radially like the spokes of a wheel around a branch of thehepatic vein, called the central vein or central venule since it reallyhas the structure of a venule. Each hepatic plate contains 2 rows ofhepatocytes. Between 2 rows of hepatocytes of the plate there is bilecanaliculus. Between the plates of hepatocytes there are sinusoidscapillaries. 12. Bile canaliculusHepatocytes form2 rows Sinusoid Space of Disse Hepatocytes Microvilli 13. Sinusoids capillaries are larger than conventional capillaries and less regular inshape. They are lined by thin endothelial cells and lacks abasement membrane (is absent over large areas except theperiphery and center of the hepatic lobule) Also residing on the sinusoidal walls are macrophages calledKupffer cells. These are phagocytic cells that removeparticulate material and old red blood cells from circulation.Kupffer cells are members of the mononuclear phagocytesystem. Pit cells are attached to the Kupffers cells. These cellscontain granules and they are like large lymphocytes, killercells. They make an anticancer effect. The space between the fenestrated endothelium and the cordsis named the space of Disse. 14. sinusoidsinusoid Kupffer cell 15. Perisinusoidal space (space of Disse)It contains microvilli of hepatocytes, blood plasma, processes of the Kupffers cells lipocytes (adipose cells, commonly called an Ito cells). They are located between some hepatocytes. These cells have been shown to be the primary storage site for vitamin A. They also can produce connective tissue fiber in the large amount at the cirrhosis. In the fetal liver, the space between blood vessels and hepatocytes contains islands of blood-forming cells. 16. sinusoid Lipid inclusions Ito cell 17. The blood circulation through theliver System of inflow: the liver receives blood from the hepatic artery(supplies oxygen-rich blood to the liver) and portal vein (carriesvenous blood with nutrients from digestive viscera). They branchinto lobar, segmental, interlobular, distributing branches. System of circulation: the distributing branches of vesselscontribute blood to the sinusoids which provide the exchange ofsubstances between the blood and liver cells. Sinusoids contain themixed blood. System of outflow: sinusoids drain blood from the periphery ofthe classical hepatic lobule toward its center, into the central vein.Outside hepatic lobules central veins drain into the sublobular(intercalated) veins, which join 3-4 together and drain into thehepatic vein. It drains into the inferior vena cava. 18. GALL BLADDERfunctions storageof bile concentration of bile acidification of bile send bile to the duodenum in response tocholecystokininsecreted by from enteroendocrine cells insmall intestine 19. Tunics (layers) of the Gall Bladder TUNICA MUCOSA: When the gall bladder is empty, this layer isextremely folded. When full, this layer is smoother but still has someshort folds. lamina epithelialis: composed of simple columnar epithelial cells with numerous microvilli on their luminal surfaces and connected by tight junctions near luminal surfaces. lamina propria: composed of loose connective tissue rich in reticular and elastic fibers to support the large shape changes that occur in the lamina epithelialisl; lamina propria may contain compound tubuloalveolar glands. May be mucous or serous. lamina muscularis mucosae: not present TUNICA SUBMUCOSA: present and typical TUNICA MUSCULARIS: contains much smooth muscle, poorlyorganized TUNICA SEROSA: present and typical 20. Pancreas Exocrinegland (97%) PROENZYMES for digestion of carbohydrates, proteins & fats (amylase, trypsin, lipases) Endocrinegland (3%) INSULIN and GLUCAGON (carbohydrate metabolism) 21. The exocrine pancreas Theexocrine portion of the pancreas is acompound acinar gland It has many small lobules, each of which issurrounded by connective tissue septathrough which run blood vessels, nerves,lymphatics, and interlobular ducts. Exocrine secretion by the pancreas iscontrolled by hormones and nerves. 22. The exocrine pancreas Acini:ThesecretorycellsofthepancreasarearrangedaroundAciniasmalllumen. Thepancreatic acinar cellsarehighlyactiveinproteinsynthesisforexportandthishighactivityisreflectedintheirbizonal stainingproperties.Thebasalregionofthesesecretory stainingcellsusuallystainsintenselywithhematoxylinreflectingthepresenceoflargeamountsofendoplasmicreticulumwheretheproteinisbeingsynthesizedonribosomeshomogen zone.Thepresenceofnumerouszymogengranulescontaininghighconcentrationsofproteinisreflectedintheintenseeosinstainingintheapicalregionofthesecretorycellszymogenzone.Thesegranulesaremostabundantduringfastingorbetweenmealsandleastabundantafteramealhasbeeningested. 23. Centroacinar cell These cells form the first part of the intercalatedZymogenductgranules 24. The exocrine pancreas Ducts:Thesecretoryproductoftheacinarcellsiscarriedoutofthepancreasbyaductsystemasinotherexocrineglands. ThefirstpartoftheductsystemiscalledtheintercalatedThefirstpartoftheductsystemiscalledtheduct or intralobular duct.Itislinedwithcuboidalepithelialcellsthatsecretebicarbonateionintothesecretoryproduct.Thisductactuallyextendsintotheacinarlumen,whereitswallsconsistofthepalestainingcentroacinar cells.wallsconsistofthepalestaining Intercalated ductshaveverylittleconnectivetissuearoundthembuttheyleadintolargerinterlobular ductswhichliethembuttheyleadintolargerwithinmoreprominentconnectivetissuesepta.Interlobularductsarelinedwithalowcolumnarepitheliumthatmaycontaingobletcells.Interlobularductsemptyintothemainpancreaticductsthatexitthepancreas. 25. Pancreatic juice trypsin,chymotrypsin and carboxypeptidasehydrolyse proteins into smaller peptides oramino acids; ribonuclease and deoxyribonuclease digest thecorresponding nucleic acids; pancreatic amylase digests carbohydrates; pancreatic lipase digests lipids; cholesterol esterase breaks down cholesterolesters into cholesterol and a fatty acid. 26. The endocrine pancreas. The cells of theendocrine portion of thepancreas are arrangedeither in round-to-ovalshaped areas rich inblood vessels known asthe islets ofLangerhans or theymay be scatteredthroughout the exocrineportions of the pancreasnear the acini or ducts. 27. Island of Langerhans -cells(75%)whichsecreteinsulin(stimulatesthesynthesisof -cellsglycogen,proteinandfattyacids;facilitatestheuptakeofglucoseintocells;activatesglucokinaseinlivercells).Theyarelocatedinthecentralpartoftheisland. -cells(20%)whichsecreteglucagon(effectsoppositetothoseof -cellsinsulin).Theyaregenerallylocatedperipherallyintheislets. -cells(5%)whichsecretesomatostatin,alocallyactinghormonewhich -cellsinhibits-,-cells.afewotherendocrinecells,whichsecrete pancreaticpolypeptide,whichstimulateschiefcellingastricglands, inhibitsbileandbicarbonatesecretionPP-cells,PP-cells vasoactiveintestinalpeptide(VIP),whichhaseffectssimilarto glucagon,butalsostimulatestheexocrinefunctionofthepancreas anddecreasethearterial blood pressure 1-cells, 1-cells secretin,whichstimulatestheexocrinepancreas,andmotilin,which increasesGITmotilityEC-cells(enterochomaffincells). EC-cells 28. Islet of Langerhans