The document summarizes the histology of the gastrointestinal tract. It describes the four layers of the GI tract wall - mucosa, submucosa, muscularis, and serosa. It then focuses on specific structures of the stomach, small intestine, and pancreas. Key points include the four regions of the stomach, gastric glands and their role in digestion, villi and crypts in the small intestine, and acini and islets of Langerhans in the pancreas that produce digestive enzymes and hormones. Clinical correlations are provided regarding conditions like atrophic gastritis, pernicious anemia, and acute pancreatitis.
15. 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.
18. Small intestine /duodenum
Plica circularis : mucosa
&submucosa
Villi : epithelium &
lamina propria
Microvilli : apical
cytoplasm
19. 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
28. Islet of
langerhans
Alpha cells : periphery secrete glucagon
Beta cells : centre , secrete insulin
Delta cells : periphery , secrete gastrin and somatostatin
29. 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.
30. 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.