Histology of git

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Histology of git

  1. 1. Histology of gastrointestinal tract Mbbs 2nd year 08/09/2013
  2. 2. Digestive system consist of the digestive tract and its associated glands that helps in process of digestion.
  3. 3. The gastrointestinal tract is a hollow tube with lumen of variable diameter . Wall made up of 4 layers Mucosa Submucosa Musularis Serosa
  4. 4. • Muscle layer : inner :circular outer longitudinal • Myenteric nerve plexus (Auerbach) Musuclaris • Thin layer of connective tissueSerosa • Epithelial lining • Lamina propria • Muscularis mucosa mucosa • Connective tissue • Submucosal plexus of autonomic nerve (meissner) submucosal
  5. 5. Stomach is divided into 4 regions : cardia , fundus , body and pylorus . Stomach digests the food by muscular activity converting it into chyme .
  6. 6. The muscularis consist of three layer for mixing of stomach content and turns into chyme
  7. 7. Esophagogastric junction Stomach consist of simple columnar epithelium that invaginates into lamina propia forming gastric pit . Emptyping into this pit are glands .
  8. 8. Regions of stomach
  9. 9. Glands in cardiac & pylorus Branched tubular with coiled secretory portion Responsible for secretion of mucus and lysozyme
  10. 10. Body/fundus
  11. 11. Gastric gland
  12. 12. Clinical correlate : • In case of atrophic gastritis both parietal and chief (Zymogenic/Peptic ) cell decrease in number and results in vitamin B12 deficiency . • Pernicious anaemia , which is a disorder of erythrocyte forming mechanism is caused by lack of IF , and Vitamin B12.
  13. 13. Small intestine
  14. 14. Small intestine /duodenum Plica circularis : mucosa &submucosa Villi : epithelium & lamina propria Microvilli : apical cytoplasm
  15. 15. Mucosa Surface epithelium : enterocytes & goblet cells Lamina propria : Muscularis : Surface epithelum & lamina propria : villi Between villi are openings of short tubular glands : intestinal crypts or crypts of liberkuhn
  16. 16. Villus contain microvasculature and lymphatics called lacteals .
  17. 17. Intestinal gland or crypts of liberkuhn • Goblet cells • Paneth cells • Enteroendocrine cells • Stem cells
  18. 18. Submucosa has large clusters of branched tubular mucous gland , the duodenal gland or brunner gland .
  19. 19. Pancreas
  20. 20. • Mixed exocrine and endocrine gland • Produces both digestive enzymes and hormones . • Digestive enzymes : exocrine portion • Hormones : endocrine epithelial cells
  21. 21. Pancreatic acini
  22. 22. pancreas
  23. 23. Islet of langerhans Alpha cells : periphery secrete glucagon Beta cells : centre , secrete insulin Delta cells : periphery , secrete gastrin and somatostatin
  24. 24. Clinical correlate In acute necrotizing pancreatitis, the proenzymes may be activated and digest the whole pancreas, leading to very serious complications. Possible causes are alcoholism, gallstones, metabolic factors, trauma, infection, and drugs.
  25. 25. Clinical correlate Acute pancreatitis : Damage to the pancreatic acinar cells releases pancreatic enzymes into the local tissues. These powerful enzymes cause death of pancreatic tissue and severe inflammation termed acute pancreatitis. The release of pancreatic lipase causes death of local fat cells (fat necrosis). Pancreatic amylase is released and can be detected at high levels in the blood. This is a severe life-threatening condition.

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