Digestive System

1. Digestive System General Function Physical/ chemical breakdown of foods so it can be absorbed into the bloodstream and used by the cells/ tissues and eliminate non-digestible substances produced during metabolism

2. Function • Digestion- Conversion process of food • Absorption- Digested nutrients are transferred to the blood stream • Elimination- Waste products removed from the body

3. Digestion • Process of changing foodstuffs into usable substances • mechanical • chemical

4. Digestive process cont. • Mechanical digestion: physical preparation of food for chemical digestion, mixing of food with saliva by tongue, churning an d mixing of food in stomach, segmentation, in intestine • Chemical digestion: catabolic process in which large food molecules are broken down into smaller molecules by enzymatic hydrolysis

5. Digestive Process • Ingestion: process of taking food into the digestive tract • Propulsion: process of moving food through the alimentary canal (swallowing, peristalsis)

6. Continued • Absorption: transported of digested end products from the GI tract into the capillaries and lymph vessels • Defecation: elimination of indigestible materials and waste form the body

7. ORGANS

8. Structures of the Alimentary Canal • Approximately 30 Ft. long • Oral Cavity: Mouth (stoma) receives and tastes food physical breakdown of food partial digestion by saliva lubricate food • hard palate: bony structure, separates mouth from nasal cavity

9. Salivary Glands • Parotid; at ear/ upper jaw • Submandibular and sublingual • Saliva: lubricates food for swallowing and helps with speech, body produces 1500 cc/ 24 hrs. • Contains enzyme (salivary amylase) which begins chemical breakdown of CHO and starches into sugar

10. Tongue • Muscular organ with taste buds (sweet, salt, sour, bitter) on sides of papillae • Maintain placement of food for chewing and swallowing and speech

11. Teeth • 20 deciduous teeth form 6 months to 2 years • 32 permanent teeth; incisors, canines, premolars, molars, cuspids, bicuspids • Enamel, dentin, pulp cavity, cementum • mastication: chewing • Bolus: Mass of chewed food

13. Pharynx and Esophagus • Passageway 10 inches long, food only here 4-8 secs., no chemical change takes place • Pharynx: throat tube that carries food and air • Epiglottis: flap that covers the trachea (windpipe) when food or water is swallowed

14. Esophagus • Muscular tube behind the trachea, carries food to the stomach by rhythmic wavelike motion (peristalsis) • Stricture: narrowing due to trauma, infection, spasms, tumors • Regurgitation: backward flow of food from stomach to esophagus • Reflux esophagitis: inflammation due to regurgitation

15. Stomach • Food stays in stomach for 3-4 hours for physical and chemical breakdown • LUQ • Fundus, body, antrum • Rugae folds in stomach to increase surface area • Sphincters: cardiac and pyloric, prevent reflux

16. Stomach

17. Gastric Enzymes • Pepsin (protein) • rennin lipase (fats) • HCL ( kills bacteria, helps in absorption of Fe, activates pepsin) • Chyme (gastric juices plus digested food)

18. Small Intestine • Approximately 21 Ft. long/ 1 inch diameter. • 80% of absorption occurs here, 3 sections • Duodenum (10-12 inches) • Jejunum (8 feet) • Ileum (final 12 feet)

19. Duodenum • Receives chyme • Pancreatic juice: amylopsin (sugars), trypsin (proteins), lipase (fats) • Gallbladder: bile (emulsifies and breaks down fats) • Intestinal juices; maltase/sucrase/lactase (breakdown sugars)

20. Ileum • Connects to large intestine at cecum • process of digestion completed • Most absorption occurs here • Villi, fingerlike projections containing blood capillary loop and lymphatic vessels for absorption • Enzymes stimulate intestinal secretions • Hormones inhibit intestinal secretions

21. Large Intestine • 5 feet/ 2 inches in diameter • Ileocecal valve: circular, shincter muscle, prevents food from returning to ileum • Cecum: blind pouch at beginning of large intestine, lower end is appendix • Colon: absorbs water, remaining nutrients, electrolytes, storage of indigestible material until elimination, transport waste

22. Colon • Ascending (right) • Transverse • Descending (left) • Sigmoid • Rectum: Final 6-8 inches, storage of feces • Anal Canal: Outlet of rectum; 2 sphincters • Fecal matter non-digestible waste products and bacteria

23. Accessory Organs • Liver • Gallbladder • Pancreas • Salivary Glands • Tongue • Teeth

24. Liver • Largest gland/ solid organ of the body • RUQ under diaphragm • secretes one liter of bile every 24 hours • Biliary tree

26. Function of liver • Function: Manufacture blood proteins (ie antibodies and blood clotting factors (ie. Heparin) • Stores iron, copper, vitamin A/D/B12 and glycogen • Produces bile for fat digestion • Detoxifies blood (poisons absorbed in small intestine)

27. Gallbladder • Pear shaped muscular sac under the liver • Stores bile (500- 600 ml stored) • Fatty foods enter duodenum and stimulate CCK hormone which contracts Gallbladder to release bile and emulsify fat and stimulate peristalsis • Bile pigment: bilirubin

28. Pancreas • Behind the stomach; head attached to stomach and tail attached to spleen • Exocrine functions:acini cells secrete digestive juices and bicarbonate ions (adjust pH) • Endocrine functions: Carbohydrate metabolism (CHO) • Insulin and Glucagon secreted for CHO metabolism

30. The End Next Digestive Diseases