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Digestive Sys tem Digestive Glan ds

Digestive System Digestive Glands

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Digestive System Digestive Glands. Components of Digestive Glands. Salivary glands Pancreas Liver. Small digestive glands: found in the wall of digestive tract Accessory glands (large digestive glands). General structure of Digestive Glands. Parenchyma: (functional portion of an organ ) - PowerPoint PPT Presentation

Text of Digestive System Digestive Glands

  • Digestive SystemDigestive Glands

  • Components of Digestive GlandsSmall digestive glands: found in the wall of digestive tractAccessory glands (large digestive glands)Salivary glandsPancreasLiver

  • General structure of Digestive GlandsParenchyma:(functional portion of an organ) acini/gland cells ductsStroma: (non-functional portion of an organ) capsule CT inside the organ

  • Salivary Glands

  • Salivary GlandsGeneral structure of the large salivary glandsParenchymaacinusductSerous acinusMucous acinusSeromucous/mixed acinusIntercalated ductStriated/secretory ductInterlobular ductExcretory duct

  • Model (structure of the large salivary glands)

  • Salivary GlandsStructural characteristic of gland cell:Serous acinus: comprised by serous cells. zymogen granules in apical cytoplasm.Mucous acinus: comprised by mucous cells. mucinogen granules in cytoplasm.Seromucous acinus: comprised by both cells./mixed acinus demilume

  • Serous acinus zymogen granules in apical cytoplasm.

  • Serous cell:Basal lamina(bl);Connective tissue (ct);Desmosome (d);Endothelium (en);Golgi comples (g);Intercellular space (is);Lumen (l);Microvilli (mi);Mitochondria (m);Nucleus (nu);RER (re);Secretion granule (sg).10.000x

  • Mucous acinus: mucinogen granules in cytoplasm.

  • Detail of mucous cells:mucous cell (sc);Golgi complex (gc);Intercellular space (is);Secretion granule (sg);Lumen (l);Nucleus (n);RER (re).10000x.

  • Seromucous acinus/mixed acinusdemilume

  • Salivary GlandsAcinusDuctIntercalated duct: Simple squamous/cuboidal epith. Striated/secretory ducts: simple tall columnar epith.Interlobular duct: pseudostratified columnar epith.Excretory ducts: stratified squamous epith.

  • Salivary GlandsIntercalated duct:Simple squamousor cuboidal epith.

  • Salivary GlandsIntercalated duct: simple squamous or cuboidal epith.

  • Detail of intercalated duct cellBasal laminar (bl);Desmosome (d);Nerve fibers (nf);Golgi complex (g);Intercellular space (is);Mitochondria (m);Nucleus (nu);RER (re).13.000x

  • Salivary GlandsStriated/secretory duct: simple tall columnar epith.

  • Salivary GlandsStriated /secretory duct

  • Salivary GlandsStriated/secretory ductThe secretory ducts, which are continuous with intercalated ducts, are wider and lined with a simple columnar epithelium. As the secretion from the acini passed through the secretory ducts, the epithlium can re-absorb sodium (Na+) and water from the lumen to the interstitium and transport potassium (K+) into the saliva, thus changing the consistency of the saliva. The secretory ducts drain into interlobar ducts which run between lobules.

  • Salivary GlandsInterlobular duct: excretory duct:Pseudostratified columnar epith. Stratified squamous epith.

  • Salivary glandsIncludeParotid G.Submandibular G.Sublingual G.Function:Moistening food.Carbohydrate digestion.Secrete IgA.

  • Pancreas The pancreas is a lobular organ. The pancreas has both exocrine functions (releases digestive enzyme secretions into the intestines) and endocrine functions (releases hormones into the blood).

  • Pancreas

  • Parenchyma

  • Parenchyma

  • Pancreas

  • Exocrine Pancreas

  • Exocrine PancreasIt releases the pancreatic juice.Pancreatic juice contain many kinds of enzyme:amylase: hydrolyses starch & glycogen.lipase: hydrolyzes triglycerides into fatty acids and mono-glyceridescholesterol esterase: breaks downtrypsin and chymotrypsin: hydrolyze proteins.ribonuclease & deoxyribonuclease: split nucleic acids.

  • PancreasEndocrine pancreasIslets of LangerhansScatter throughout the exocrine pancreas.Three types of cells:A-cells (20%) glucagon (glycogen glucose)B-cells (75%) insulinD-cells (5%) somatostatinCapillaries: each islet is richly supplied with blood vessels.

  • PancreasEndocrine pancreas

  • GlucagonPurpose:Assist insulin in regulating blood glucose (sugar) in the normal range Action: Forces many cells of the body to release (or produce) glucose (increasing blood sugar) Secreted in response to: Low blood glucose Secretion inhibited by: High blood glucose Disease due to deficient action: Some times nothing, sometimes hypoglycemia Disease due to excess action: Hyperglycemia Tumor called:Glucagonoma InsulinPurpose:Regulate blood glucose (sugar) in the normal range Action: Forces many cells of the body to absorb and use glucose thereby decreasing blood sugar levels Secreted in response to: High blood glucose Secretion inhibited by: Low blood glucose Disease due to deficient action: Diabetes Disease due to excess action: Hypoglycemia Tumor called:Insulinoma.

  • Liver

  • LiverGeneral IntroductionThe largest gland (--2% of body weight in adult).respectively receives both venous & arterial blood through the portal v. (--75%) & hepatic A (--25%).CT of capsule extended into the parenchyma, forming classical liver lobules.Functions as an exocrine gland (secreting bile) and other very important roles.

  • Liver

  • LiverStructrues of Liver lobule

  • LiverStructures of Liver lobule

  • Model of Liver Lobule

  • LiverStructures of Liver lobulesix-sided prism with a central V. at its center.sheets of hepatocytes (or hepatic plates) extend radially from the central V.sinusoids between hepatic plates.Portal triads (or portal area):In the corner of lobules.

  • Structures of Liver lobuleLiver

  • Portal Triads (or Portal Area)LiverDefinition: The area of CT found in the angles where adjacent hepatic lobules meet.Components: CT.+portal triad interlobular A interlobular V interlobular bile duct

  • Portal Triads (or Portal Area)Liver

  • Portal Triads (or Portal Area)Liver

  • SinusoidsLiverDilated anastomosing venules between the hepatic plates.Blood pathway: peripherycentral V.Kupffer cells line in the wall of sinusoids.EM (endothelium of sinusoid) significant gaps; numerous fenestration; incomplete basal lamina.

  • SinusoidsLiver

  • TEMSinusoids

  • Sinusoids

  • HepatocyteLivertypically large polyhedral cells with large round centrally located nucleus.abundance of organelles relates to its functions: Mitochondria: provide energy RER: protein synthesis SER: bile formation/ metabolism of lipids and hormones/detoxification. Lysosome: defence Microbody: detoxification Inclusions: glcogen particles, lipid droplets and pigments.

  • HepatocyteLiver

  • Functions of HepatocyteLiverProduce bile.Degrade glycogen to glucose under regulation of hormones.Involve the blood lipid metabolism.Synthesize the blood plasma proteins: albumin;fibrinogen, and so onDetoxification

  • Bile CanaliculusLiverDefinition: the tubular space limited by plasma membrane of two adjacent hepatocytes.Structure:LM: network-like structures are seen by silver impregnation.EM: plasma membrane of adjacent hepatocytes forms the wall of bile canaliculi. tight junctions form seals.

  • Bile Canaliculus

  • Bile Canaliculus

  • Perisinusoidal space (Disses Spaces)LiverA space between endothelium & hepatocyte.Be visible under EM.Occupy by numerous microvilli of hepatocytes.Fill with blood plasma.have fat-storing cells (storing fat & vitamin A)A site for substance exchangeBetween the blood & the hepatocytes.

  • Perisinusoidal space (Disses Space)

  • Perisinusoidal space (Disses Space)

  • Sinusoids

  • LiverThree functional surface on the surface of hepatocyte

  • LiverBlood Supply

  • Liver

  • Liver

  • Liver

  • Liver