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Digestive System

Delve into the digestive system, its organs, and processes. Learn about ingestion, digestion, absorption, and more. Explore alimentary tract, nerve supply, salivary glands, and metabolic functions.

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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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