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/Accessory Organ 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 Body or great curvature Pylorus Upper part
Middle section
Pylorus
Lower portion

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

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

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

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

14. Digestive Juices in the 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 valve into 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. Click here to play Digestion animation
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