消化腺（全英文）课件

,Digestive System Digestive Glands,Components digestive glands found in the wall of digestive tract accessory digestive glands: salivary glands / pancreas / liver General structure * Parenchyma (functional portion of an organ, as distinguished from the supporting tissue): acini / gland cells duct * Stroma (unfunctional portion of an organ): capsule, CT inside.,Salivary glands * Parotid * Submandibular G. * Sublingual G. Three types of acini * serous * mucous * seromucous Function: * moistening food * carbohydrate digestion * Secrete IgA,Pancreas,positioned retroperitoneally on the posterior wall of the abdominal cavity at the level of the second and third lumbar vertebrae. no distinct capsule, but is covered by a thin layer of LCT both an exocrine & endocrine gland. * exocrine part: produces pancreatic juice * endocrine part: produce hormones,Components of the exocrine pancreas consists of serous glands acini filled with acidophilic zymogen granules intercalated duct extends into the centre of the acini, which is lined by centroacinar cells duct system: intercalated ducts (low columnar or cuboidal epith.) Interlobular ducts (columnar epith.) Main pancreatic ducts ( tall columanr epth.) major duodenal papilla,Function of pancreatic juice: * Trypsin, chymotrypsin * amylase hydrolyses starch & glycogen * lipase hydrolyses triglycerides into fatty acids and monoglycerides * cholesterol esterase breaks down cholesterol esters into cholesterol and a fatty acid.,Components of the Endocrine * Islands of Langerhans scattered throughout the exocrine pancreas. * Vascularization (many fenestrated cap.) is more extensive than that of the exocrine acini. * Three different types present A-cells (20%): glucagon producer B-cells (75%): insulin producer D-cells (5%): somatostatin producer,Liver * largest gland ( 2% of body weight in adult). * receives both venous & arterial blood through the portal V. (75%) & hepatic A (25%), respectively. * CT of capsule extended into the parenchyma, forming “ classical” liver loblules ( basic structure units). * functions as an exocrine gland (secreting bile).,Structures of liver lobules * six-sided prism with a central V. at its centre * delimited by interlobular CT * portal triads in the corner of lobules (portal area) * anastomosing plates of hepatic cells extended radially from the central V. * sinusoids form between hepatic plates,Portal areas *definition: a area found in the angles where adjacent hepatic lobules meet. * components: CT. + portal triad interlobular A interlobular V interlobular bile duct,Sinusoids * dialated anastomosing venules between the hepatic plates * blood pathway: periphery central v. * Kupffer cells lined in the wall of sinusoids * EM: significant gaps numerous fenestration incomplete basal lamina,Hepatocytes * make up about 80% of the cells in the liver. * typically large polyhedral cells with large round centrally located nuclei. * abundance of organelles related to the functions Mitochondria: energy providing RER: protein synthesis SER: bile formation / metabolism of lipids and hormones / detoxification. Lysosome: replacement and defence Microbody: detoxification. Inclusions: glcogen particles, lipid droplets and pigments.,Hepatocyte function * Produce bile * mediate carbohydrate reserves glycogen is degraded to glucose under regulation of hormones * Blood lipid metabolism * Synthesis of plasma proteins albumin: major plasma protein fibrinogen thrombin clotting factor III,Bile Canaliculi Definition: tubular space limited by plasma membrane of two adjacent hepatopcytes. Structure: LM: network-like structures are seen by silver impregnation EM: * plasma membrane of adjacent hepatocytes form the wall of bile canaliculi * tight junctions form seals,Blie canaliculi stained by silver impregnation,Perisinusoidal sapce (space of Disse) a space between the endothelium & hepatocyte be visible under EM occupied by numerous microvilli of hepatocytes filled with plasma fat-storing cells (storing fat & vitamin A) a site for exchange between the blood & hepatocytes.,*cell junction surface,* Perisinusoidal surface: face to perisinusoidal space,* bile canalicular surface: face into the bile canaliculus,Interlobule A.&V.,Three types of functional surface in hepatocyte,Hepatic Blood Supply,Portal V interlobular V ,Hepatic Ainterlobular A ,sublobular V,sinusoids,central V,hepatic V,Inferior vena cava,(75%),(25%),Bile canaliculi periperal bile ductules ( Herings ) interlobular bile duct Left & right hepatic ducts Common hepatic duct Common bile duct Duodenum papilla,Cystic duct,Gall bladder,Biliary Passages,Classification of Lobules Classic lobule: A hexagonal structure with the central vein at its center; at the six corners of the lubule are hepatic triads. 2. Portal lobule: A tria