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Prof Dr Amira Shubbar MRCP, FRCP

Lectures in Gastroenterology. Prof Dr Amira Shubbar MRCP, FRCP. Functional Anatomy & Physiology. Upper esoph. sphincter. Lower esop. Sphincter. Pylorus. Receptive relaxation Regulated emptying. Migrating motor complex. Segmenatation Propulsive peristaltic contraction.

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Prof Dr Amira Shubbar MRCP, FRCP

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  1. Lectures in Gastroenterology Prof Dr Amira Shubbar MRCP, FRCP

  2. Functional Anatomy & Physiology

  3. Upper esoph. sphincter Lower esop. Sphincter Pylorus Receptive relaxation Regulated emptying Migrating motor complex Segmenatation Propulsive peristaltic contraction Ileocecal Valve Anal sphincter

  4. Anatomy & Function (The swallowing wave) The Esophagus

  5. Normal gastric & duodenal anatomy

  6. Gastric secretion • Parietal cells :HCL + Intrinsic factor. • Chief cells :Pepsinogen +mucus. • G cells :Gastrin. • D cells : Somatostatin. • Protective factors: Mucus + Bicarbonate • Oxyntic gland: ghrelin

  7. Gastric distension & food stimulate the release of Gastrin from G cells which will act on CCk-2R on ECL cells releasing Histamine which will act on H2 receptors in the Parietal cells. • Gastrin act direct on the Parietal cells too. • Vagal stimulation through anticipation or smell of food act on the Ach-R M3 receptors on the parietal cells • Hydrogen + Chloride are secreted in response to H/K ATPase (Proton pump ) from the apical membrane of the Parietal cell.

  8. What switches off the parietal cell? Somatostatin D cell CCK I cell Secretin S cell GIP K cell glucose-depedentinsulinotrophic polypeptide

  9. Small Intestine Anatomy

  10. Functions of the small intestine • Digestion • Absorption • Protection against ingested toxins & immune regulation.

  11. Carbohydrates • Starch Alpha-limit dextrins containing 4-8 glucose molecules. Disaccharide Maltose Trisaccharide Maltotriose Disaccharides are digested by enz. in microvilli to monosaccharides glucose , fructose & galactose which diffuse through enterocytes

  12. Protein • Protein in the stomach converted by pepsin to A.A & polypeptide which stimulate secretion of pancreatic proenzymes trypsinogen , chymotrypsinogen , proelastases & procarboxypeptidase. • Trypsinogen converted to trypsin on enterocyte brush border . • Protein digested by trypsin to oligopeptides & A.A. • Oligopeptides hydrolyzed to dipeptides , tripeptide & A.A then actively transported into the enterocytes & then to the portal circulation.

  13. Protective Function of the small intestine • Immunology & T Lymphocytes , Macrophages & Mast cells are found through out GIT. • MALT :constitute 25% of total lymphatic tissue of the body. • Luminal Ag stimulate B cells to Plasma cell in peyers patches to mesenteric LN then thoracic duct & blood stream & lamina propria & secret IgA. • T lymphocyte localize the plasma cell at the site of Ag. • Macrophages: Phagocyte foreign material & secret cytokines.

  14. Mucosal Barrier • Mucus. • Enterocytes membranes & tight junctions between them. • Renewal of the intestinal cells every 48 hours.

  15. Pancreatic structure & function

  16. Pancreas • Exocrine pancreas is necessary for the digestion of protein , fat & carbohydrate. • Pancreatic enzymes: Amylase: Starch & glycogen Lipase: TG Colipase: TG Proteolytic enzymes: Protein & polypeptide.

  17. The normal colon, rectum & anal canal

  18. Colon • For absorption of water & electrolytes & storage organ. • Contractile activity : Segmentation. Peristaltic contraction

  19. Gut hormones and peptides

  20. Gut hormones and peptides (2)

  21. Gut hormones and peptides (3)

  22. Investigations of GIT Diseases

  23. Endoscopy US, CT MRI Contrast studies Plain Radiograph GIT Motility Radioisotope Tests Imaging Histology Investigations of GIT diseases Tests of function Tests of structures Absorption Pancreatic Exocrine function Tests of infection Mucosal Inflammation/ permeability Bacterial culture Serology Breath Tests

  24. Tests of Structure 1- Imaging

  25. Plain Radiograph • It is useful in diagnosis of intestinal obstruction or paralytic ileus • The outlines of soft tissues e.g. liver, spleen kidneys may be visible • Calcification in the abdominal structures as well as calculi can be detected • Abdominal radiographs are not useful in GIT bleeding • CXR shows the diaphragm and erect films may detect sub-diaphragmatic free air in cases of perforation

  26. Plain Radiograph Normal Plain Abdominal Radiograph

  27. Plain Radiograph Normal Plain Abdominal Radiograph showing the identification of transverse colon

  28. Air under the diaphragm (perforated DU)

  29. Small Intestinal obstruction (multiple fluid levels)

  30. Hiatus hernia (fluid levels behind the heart)

  31. Calcification of the pancreas (chronic pancreatitis)

  32. Toxic megacolon

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