Gastroenterology

1. Gastroenterology The medical specialty that studies the anatomy and physiology of the gastrointestinal system and uses diagnostic tests, medical and surgical procedures, and drugs to treat gastrointestinal diseases.

2. Anatomy and Physiology Gastrointestinal System Begins at the mouth, continues through the thoracic cavity, and fills most of the abdominal cavity Upper gastrointestinal system includes the structures from the mouth through the stomach

3. Anatomy and Physiology (con’t) Gastrointestinal System (con’t) Lower gastrointestinal system includes the small and large intestines Purpose is to digest food, absorb nutrients, and remove undigested material (waste) from the body

4. Figure 3-1 Gastrointestinal system

5. Anatomy of the Gastrointestinal System Oral Cavity and Pharynx Begins in the mouth, or oral cavity Oral cavity contains the teeth; tongue; hard palate; and soft palate with its fleshy, hanging uvula. Saliva also contains an enzyme that begins the process of digestion.

6. Anatomy of the Gastrointestinal System (con't) Oral Cavity and Pharynx (con’t) There are three pairs of salivary glands: the parotid glands, the sublingual glands, and the submandibular glands. The teeth tear, chew, and grind the food during the process of mastication. The tongue moves food toward the teeth and mixes food with saliva.

7. Anatomy of the Gastrointestinal System (con't) Oral Cavity and Pharynx (con’t) Swallowing or deglutition moves food into the throat or pharynx. When food is swallowed, the epiglottis closes the entrance to the larynx, so that food in the back of the throat, pressing on the uvula, does not initiate the gag reflex.

8. Figure 3-2 Oral cavity and pharynx

9. Figure 3-3 Salivary glands

10. Anatomy of the Gastrointestinal System (con't) Esophagus A flexible, muscular tube that connects the pharynx to the stomach.

11. Anatomy of the Gastrointestinal System (con't) Stomach Divided into four areas: the cardia, fundus, body, and pylorus. The gastric mucosa is arranged in thick, deep folds known as rugae which expand as the stomach fills with food.

12. Anatomy of the Gastrointestinal System (con't) Stomach (con’t) Two sphincters (muscular rings) keep food in the stomach. The lower esophageal sphincter is located in the distal esophagus.

13. Figure 3-4 Stomach

14. Anatomy of the Gastrointestinal System (con't) Small Intestine The small intestine is a long, hollow tube that receives chyme from the stomach. It is divided into three parts: the duodenum, jejunum, and ileum.

15. Figure 3-5 Small and large intestines

16. Anatomy of the Gastrointestinal System (con't) Large Intestine A larger, hollow tube that receives undigested material and water from the small intestine. Consists of the cecum, colon, rectum, and anus.

17. Anatomy of the Gastrointestinal System (con't) Large Intestine (con’t) Waves of peristalsis slowly move undigested material through the large intestine as water is absorbed through the intestinal wall and into the blood. The colon is the longest part. It travels through all four quadrants of the abdomen as the ascending colon, transverse colon, descending colon, and sigmoid colon.

18. Anatomy of the Gastrointestinal System (con't) Abdomen and Abdominopelvic Cavity Contains the largest organs of the gastrointestinal system. The walls of the abdominopelvic cavity are lined by peritoneum, a membrane that secretes peritoneal fluid. This watery fluid fills the spaces between the organs and allows them to slide past each other during the movements of digestion.

19. Anatomy of the Gastrointestinal System (con't) • The blood supply to the stomach, small intestine, liver, gallbladder, and pancreas comes from the celiac trunk of the aorta, the largest artery in the body.

20. Anatomy of the Gastrointestinal System (con't) Liver The liver is the largest solid organ in the body, located in the upper right abdominal cavity. An accessory organ of digestion that contributes to, but is not physically involved in, the process of digestion.

21. Figure 3-6 Biliary tree

22. Anatomy of the Gastrointestinal System (con't) Gallbladder An accessory organ of digestion posterior to the liver. Concentrates and stores bile from the liver.

23. Anatomy of the Gastrointestinal System (con't) Pancreas An accessory organ of digestion posterior to the stomach. Presence of food in the duodenum causes the pancreas to secrete digestive enzymes into the pancreatic duct to the duodenum. Also functions as an organ of the endocrine system.

24. Physiology of Digestion There are two parts to digestion: Mechanical Chemical Mechanical digestion uses mastication, deglutition, and peristalsis to break down foods. Mechanical digestion also involves breaking apart fats in the duodenum.

25. Physiology of Digestion (con't) • The enzyme amylase in saliva begins to break down carbohydrate foods in the mouth. • The stomach secretes the following substances that continue the process of chemical digestion: • Hydrochloric acid • Pepsinogen • Gastrin

26. Chemical digestion is completed in the small intestine. Cholecystokinin stimulates the pancreas to secrete four digestive enzymes into the duodenum: Amylase Lipase Protease Other enzymes that break down proteins Physiology of Digestion (con't)

27. The liver plays an important role in regulating nutrients such as glucose and amino acids. Excess glucose in the blood is stored in the liver as glycogen and released when the blood glucose level is low. The liver uses amino acids to build plasma proteins and clotting factors for the blood. Physiology of Digestion (con't)

28. Alimentary Canal Accessory Structures Figure 3-7 Gastrointestinal system. (Robert W. Ginn/PhotoEdit Inc.)

29. Diseases and Conditions Eating Anorexia Dysphagia Polyphagia

30. Diseases and Conditions (con't) Mouth and Lips Cheilitis Sialolithiasis Stomatitis Glossitis

31. Figure 3-8 Glossitis (Centers for Disease Control and Prevention [CDC])

32. Diseases and Conditions (con't) Esophagus and Stomach Dyspepsia Esophageal varices Gastritis Gastroenteritis Gastroesophageal reflux disease (GERD)

33. Figure 3-9 Esophageal varix (David M. Martin, M.D./Photo Researchers, Inc.)

34. Diseases and Conditions (con't) Esophagus and Stomach (con't) Heartburn Hematemesis Nausea and vomiting (N&V) Peptic ulcer disease (PUD) Stomach cancer

35. Figure 3-10 Gastric ulcer (David M. Martin, M.D./Photo Researchers, Inc.)

36. Diseases and Conditions (con't) Duodenum, Jejunum, Ileum Ileus Intussusception Volvulus

37. Figure 3-11 Intussusception of the intestine

38. Diseases and Conditions (con't) Cecum and Colon Appendicitis Colic Colon cancer Diverticulum Dysentery

39. Figure 3-12 Diverticula (David M. Martin, M.D./Photo Researchers, Inc.)

40. Figure 3-13 Diverticulitis and polyposis

41. Diseases and Conditions (con't) Cecum and Colon (con’t) Gluten enteropathy Inflammatory bowel disease (IBD) Irritable bowel syndrome (IBS) Polyp

42. Figure 3-14 Crohn’s disease

43. Figure 3-15 Colonic polyps (Staats/Custom Medical Stock Photo, Inc.)

44. Diseases and Conditions (con't) Rectum and Anus Hemorrhoids Proctitis Rectocele

45. Diseases and Conditions (con't) Defecation and Feces Constipation Diarrhea Flatulence Hematochezia Incontinence Steatorrhea

47. Diseases and Conditions (con't) Abdominal Wall and Abdominal Cavity Adhesions Hernia Peritonitis

48. Figure 3-16 Hernia (From Rudolph, A.M., Hoffman, J.I.E., & Rudolph, C.D. (Eds.) 1991. Rudolph’s Pediatrics. (19th ed., p. 1040))

49. Figure 3-17 Peritonitis (Custom Medical Stock Photo, Inc.)

50. Diseases and Conditions (con't) Liver Ascites Cirrhosis Hepatitis