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Digestive System

Digestive System. Dr. Manodeep Chakraborty. Digestion Digestive system Functions of Digestive system Ingestion Propulsion Digestion Absorption Secretion Elimination Regulation of water balance Regulation of electrolyte balance Excretion. Organs of digestive system

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Digestive System

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  1. Digestive System Dr. Manodeep Chakraborty

  2. Digestion • Digestive system • Functions of Digestive system • Ingestion • Propulsion • Digestion • Absorption • Secretion • Elimination • Regulation of water balance • Regulation of electrolyte balance • Excretion

  3. Organs of digestive system # Alimentary tract or GIT • Mouth • Pharynx • Oesophagus • Stomach • Small intestine • Large intestine • Rectum & anal canal # Accessary glands/organs • Salivary glands • Pancreas • Liver & biliary tract • Gall bladder

  4. Alimentary tract (GIT) • Histology • Adventitia or serosa • Parietal • Visceral • Muscle layer • Submucosa • Mucosa lining • Mucous membrane • Lamina propria • Musculari’s mucosa

  5. Nerve Supply • Parasympathetic • One pair of cranial, vagus, sacral nerves • Sympathetic • Spinal cord & lumbar region

  6. Mouth • Vestibule • Palate • Uvula • Palatine tonsil

  7. Tongue • three varieties of papillae • Vallate papillae • Fungiform papillae • Filiform • Blood supply : Lingual branch of external carotid artery • Nerve supply : Hypoglossal nerves (12) Lingual branch of mandibular nerves Facial & glossopharangeal nerves (7 & 9) Functions : Speech, Taste

  8. Teeth • Incisions • Canine • Premolars • Molars • Structure of teeth • Bloods supply : Maxillary arteries & internal jugular vein • Nerve supply : Trigeminal nerve (5) Maxillar & mandibular nerves

  9. Salivary glands • Types • Parotid • Submandibular • Sublingual • Structure of salivary glands • Composition of Saliva • water, minerals, salivary amylase, mucus, lysozyme, immunoglobulins, blood clotting factors • Secretion of saliva • Functions of saliva • Digestion, lubrication, cleaning, nonspecific defense, taste

  10. Pharynx • Lining membrane (stratified squamous) • Middle layer : Fibrous tissue • Outer layer : Involuntary muscle

  11. Different areas of abdominal cavity

  12. Cricopharyngeal • Oesophagus

  13. Stomach • Organs associated with the stomach • Structure of stomach • Walls of stomach • Four layer as that of alimentary canal • Muscle layer • Congitudinal fibre • Circular fibre • Oblique fibre • Mucosa • Blood supply

  14. Chyme • Gastric juice • Function • Secretion of gastric juice • Cephalic phase • Gastric phase • Intestinal phase

  15. Functions of the stomach • Temporary storage • Chemical digestion • Mechanical digestion • Absorption • Defense • Preparation of iron for absorption • Production & secretion of intrinsic factor • Regulation of the passage of gastric contents into the duodenum • Secretion of the hormone gastrin

  16. Small intestine • Duodenum • Jejunum • Ileum • Structure of small intestine • Peritoneum • Mucosa

  17. Intestinal juice (15oo ml) • Composition • water, mucus, mineral salts, enzymes, hormones Enzymes : Dipeptidase, Tripeptidase, Oligopeptidase, Aminopeptidase, Carboxypeptidase Carbohydrate digesting enzyme : Sucrase, maltase, iosomaltase, lactase Lipid digesting enzymes : Intestinal lipase, Cholesterol esterase, lecithinase Hormones : Enterogastrin, secretin, cholecystokinin • Functions • Peristalsis • Secretion of intestinal juice • Completion of chemical digestion of carbohydrates • Protection against infection • Secretion of cholecystokinin • Absorption of nutrients • Chemical digestion in the small intestine

  18. Pancreatic juice (1-2litres) • Composition • Enzymes Proteolytic enzymes • Trypsinogen • Chymotrypsinogen • Procarboxy peptidase • Collagenase • Elastase • Nuclease – DNAase RNAase

  19. Functions of pancreatic juice • Digestion of protein (Trypsinogen & Chymotrypsinogen) • Digestion of carbohydrate (Amylase) • Digestion of fats (Lipase)

  20. Bile (500 – 1000 ml) • Composition Bile acid : Cholic acid, Chenodeoxycholic acid Bile pigments : Bilirubin, Biliverdin, Urobilinogen, Stercobilin Cholesterol, Fatty acids, Phospholipids

  21. Functions of bile • Absorption of nutrients • Diffusion • Active transport

  22. Large intestine • Cecum • Colon • Ascending • Transverse • Descending • Sigmoid • Rectum • Anal canal

  23. Functions of the colon • Absorption, mass movement, microbial activity, defaecation • Composition of faeces

  24. Pancreas • Exocrine • Endocrine

  25. Liver • Portal tissue

  26. Structure Of TS of liver

  27. Functions • Carbohydrate metabolism • Fat metabolism • Protein metabolism • Production of heat • Secretion of bile • Storage of glucagon

  28. Gall bladder • Functions of the gall bladder • Reservior for bile • Concentration of the bile by upto 10-15 fold • Release of stored bile

  29. Absorption of digested food • Mechanism of absorptions are • Diffusion • Faciliated diffusion • Active transport • Vesicle mediated transport

  30. Metabolism • Catabolism • Anabolism • Metabolic rate • Basal metabolic rate • Central metabolic pathways • Glycolysis • Citric acid cycle • Oxidative phosphorylation

  31. Metabolism of carbohydrate • Metabolism of protein • Metabolism of fat

  32. Diseases of digestive system

  33. Diseases of mouth • Acute ginivitis • Rare acute condition with severe ulceration of gums occurs that affect the lips mouth, throat, palatine tonsil • Caused by Borrelia vincerti, Fusiform bacillus • Diseases of salivary glands • Mumps • Acute inflammatory condition of salivary glands especially the parotid • Caused by mumps virus

  34. Calculus formation • Crystallization of mineral salts in saliva • Partially or completely block the ducts leading to swelling of the glands, a predisposition to infection and atrophy • Diseases of oesophagus • Oesophagitis • Swallowing of caustic material, acquire fungal infection by immuno compromised people, viral infections e.g. Herpes simplex • Sever injury, healing causes fibrosis, risk of development of oesophageal structure as the fibrous tissue shrinks

  35. Reflux oesophagitis • Indigestion or heat burn due to regurgitation of acidic gastric juice into oesophagus • Irritation, Inflammation, Pain, Ulceration, Haemorrhage • Reflux of gastric content is associated with increase in intraabdominal pressure e.g. in pregnancy, constipation & obesity • High acidic content of gastric juice • Low levels of secretion of hormone gastrin

  36. Achalasia • Peristalsis of the lower oesophagus is impaired • Lower oesophageal sphincter fails to relax during swallowing causing dysphagia • Regurgitationn of gastric content and aspiration pneumonia

  37. Gastritis • Either an excess of acid in the stomach or insufficient mucus to protect the surface epithlium • Causes for gastrtis • Prolonged use of NSAIDS • Excessive alcohol consumption • Food poisoning • Ingestion of corrosive poisons, acid & alkalies • Regurgitation of the bile into the stomach • Helicobacter pylori

  38. Peptic ulcer disease • It is a circumscribed ulceration of mucus membrane penetrating through the muscularis mucosa & occurring in areas bathed by acid and pepsin in the stomach & duodenum. • Gastric ulcer • Duodenal ulcer • Complications : Haemorrhage, Perforation, Gastric outflow obstruction, Development of malignant tumour

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