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Overview of the Digestive System

Learn about the digestive system, its organs and functions, the process of digestion, and common disorders. Understand the importance of digestion in converting food into nutrients for the body. Discover how aging can affect digestion.

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Overview of the Digestive System

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  1. Chapter 18 Digestive System

  2. Digestive System • Food must be converted by physical and chemical changes before it can be used by the cells; this process is called digestion • Enzymes • Alimentary canal • Accessory organs

  3. Layers of the Digestive System • Mucosa • Innermost lining • Submucosa • Circular muscle • Longitudinal muscle

  4. Lining of the Digestive System • Peritoneum • Parietal • Visceral • Mesentery • Greater omentum • Peritonitis

  5. Functions of the Digestive System • Break down food physically • Change food chemically • Absorb the nutrients • Eliminate the waste products of digestion

  6. Organs of Digestion • Mouth (oral or buccal cavity) • Tongue/accessory organ of digestion • Salivary glands

  7. Teeth/AccessoryOrgan of Digestion • Gingivae or gums • Teeth • Food chewed or masticated • Deciduous and permanent teeth • Structure of the tooth

  8. Esophagus • Muscular tube to transport swallowed food to stomach • Esophageal wall layers • Mucosa • Submucosa • Muscular • External serous

  9. Stomach • Fundus • Upper part • Body or great curvature • Middle section • Pylorus • Lower portion

  10. Stomach • Sphincters • Cardiac sphincter • Pyloric sphincter • Four layers of the stomach wall

  11. Gastric Juices • Enteroendocrine glands • Secrete gastrin • Parietal cells • Produce HCL and intrinsic factor • Chief type cells • Produce pepsinogen

  12. Gastric Juices • Mucus cells • Secrete alkaline mucus • Rennin • Found in infants and children

  13. Small Intestine • About 20 feet long • Same four layers as the stomach • Duodenum • Jejunum • Ileum

  14. Digestive Juices inthe Small Intestine • Enzymes, secretin, and cholecystokinin • Pancreatic juices • Bile • Intestinal juices

  15. Absorption in the Small Intestine • Villi • Makes absorption possible • Each villi contains a network of blood and lymph capillaries • Digested portion passes through the villi into the bloodstream and lacteals

  16. Absorption in the Small Intestine • Undigested portion passes on to the large intestine

  17. Accessory Organs of Digestion • Pancreas • Liver • Gallbladder

  18. Large Intestine • Also called the colon • About 5 feet long • Ileum empties chyme through ileocecal valveinto large intestine • Secretes mucus to lubricate passageway

  19. Large Intestine • Cecum and appendix • Ascending, transverse, and descending colon • Sigmoid colon • Anal canal

  20. Digestive System Structures

  21. General Overview of Digestion • Bolus • Peristalsis • Digestion of protein, fats, and carbohydrates • Absorption of nutrients • Undigested substance - feces

  22. General Overview of Digestion • Action in the mouth • Action in the pharynx • Action in the esophagus • Action in the stomach • Action in the small intestine • Action in the large intestine

  23. Action in the Large Intestine • Absorption • Bacterial action • Gas formation • Fecal formation • Defecation

  24. Metabolism • Within the cells, nutrients are changed into energy • Aerobic metabolism • Oxidation • Anaerobic metabolism • Krebs cycle

  25. Metabolism • Anabolism and catabolism • Thyroid hormones

  26. Animation – Digestion Click here to play Digestion animation

  27. Effects of Aging • Decrease sensory ability of taste buds • Reduction of saliva • Loss of teeth • Slowing peristalsis

  28. Disorders – Digestive System • Stomatitis • Gingivitis • Periodontal disease • Gastroesophageal reflux disease (GERD)

  29. Disorders – Digestive System • Hiatal hernia • Heartburn • Pyloric stenosis • Gastritis • Gastroenteritis

  30. Disorders – Digestive System • Enteritis • Ulcer • Inflammatory bowel disease (IBD) • Appendicitis • Hepatitis

  31. Disorders – Digestive System • Cirrhosis • Cholecystitis • Gallstones • Pancreatitis • Diverticulosis

  32. Disorders – Digestive System • Hemorrhoids • Diarrhea • Constipation

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