1. The Digestive System

2. 2 Digestion is the process of breaking down food into nutrients that can be absorbed by cells.

3. 3 The Digestive System (cont.) The Mouth Digestion begins in the mouth with mastication. Three sets of salivary glands surrounding the oral cavity secrete saliva. Saliva contains enzymes that break down food and begin the digestion of carbohydrates. Three pairs of glands with ducts: parotid, submandibular, and sublingual glands.

4. 4 The Digestive System (cont.) The Mouth (cont.) 1. Parotid gland. 2. Submandibular gland. 3. Tongue. 4. Tooth. 5. Sublingual gland. 1 2 3 4 5

5. 5 The Digestive System (cont.) The Pharynx Passageway for food and air. Epiglottis covers the trachea when we swallow. The Esophagus Contracts rhythmically to move food to stomach. The cardiac sphincter, a group of muscles, closes the entrance to the stomach to prevent backflow of food.

6. 6 The Digestive System (cont.) The Stomach Pouchlike organ with four regions. Located in the left hypochondriac region. Receives food from the esophagus and mixes it with gastric juice to form chyme.

7. 7 The Digestive System (cont.) Small Intestines Receive chyme from the stomach. Absorption occurs over 1 to 6 hours. Has 3 parts: Duodenum. Jejunum. Ileum.

8. 8 The Digestive System (cont.) Large Intestines Waste products from digestion stay here for 12 to 24 hours. Has four main parts: Cecum. Colon: ascending, transverse & descending Sigmoid colon. Rectum.

9. 9 The Digestive System (cont.) The Liver Not within the GI tract, but performs digestive functions. Changes food nutrients into useable substances. Secretes bile to break down fat. Stores glucose and certain vitamins. Secretes bilirubin.

10. 10 The Process of Digestion-The mouth Mechanical Digestion is the process of physically breaking down food through chewing Chemical Digestion occurs when food molecules are further broken down with the help of enzymes

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12. 12 With the help of strong jaw muscles, the teeth are capable of breaking down food

13. 13 While mechanically breaking down food in the mouth, enzymes in the saliva begin to chemically break the food molecules down into useable nutrients Once the food has been reduced to a soft mush, the tongue pushes the food to the back of the mouth, causing the swallowing reflex

14. 14 Food is pushed to the esophagus, where it slides to the stomach in less than 10 seconds. Small glands in the stomach produce enzymes and acid which further break down food particles into nutrients After a few hours of being broken down, the food exits the stomach as a soupy mixture called chyme

15. 15 After leaving the stomach, chyme is pushed into the small intestine, where the process of absorption will begin. At this point, fluids produced by the pancreas to protect the small intestine from the acid in the chyme are released

16. 16 The Small Intestine is the MAIN point of absorption of nutrients into the blood (and eventually the cells). Numerous small, finger-like projections called villi poke out into the tube of the small intestine, greatly increasing its surface area. The increase in surface area allows for more absorption to occur here

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18. 18 While traveling along the digestive tract, bile is secreted into the small intestine, breaking up fats Bile is produced in the liver, although it is stored and secreted into the small intestine through the gallbladder

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20. 20 Food that cannot be directly absorbed into the blood is pushed from the small intestine into the large intestine The large intestine is capable of absorbing most of the water from the food remains, turning them into a semi-solid mass known as feces, or stool. Feces are stored in the rectum until they can be expelled.

21. 21 The Digestive System (cont.) Diseases and Disorders Anorexia nervosa – refusing to eat in order to be thin. Bulimia nervosa – binging on food and then purposely vomiting for weight loss. Obesity – usually caused by overeating, possibly a heredity defect. Can contribute to heart disease and diabetes. Halitosis – bad breath. Esophageal varices – twisted veins in the esophagus.

22. 22 The Digestive System (cont.) Diseases and Disorders (cont.) Gastroenteritis – inflammation of the stomach and small intestines. Flatulence – gas. Eructation – belching. Nausea – sick feeling in stomach. GI ulcer – sores on the mucous membrane of the GI tract. Hiatal hernia – protrusion of the stomach through an opening in the diaphragm.

23. 23 The Digestive System (cont.) Diseases and Disorders (cont.) Jaundice – yellow discoloration of the skin. Cirrhosis – chronic liver disease. Cholecystitis – inflammation of the gall bladder. Appendicitis – inflammation of the appendix. Ulcerative colitis and Crohn’s disease – chronic inflammatory diseases of the intestines.

24. 24 The Digestive System (cont.) Diseases and Disorders (cont.) Diverticulitis – inflammation of the pouches in the intestinal wall. Constipation – infrequent or difficult release of bowel movements. Diarrhea – loose, watery stools. Hemorrhoids – swollen, twisted, painful veins in the internal and external anal area.