1. The Digestive System Grade 11 Biology

2. Table of Contents • Introduction to the Digestive System • What is Digestion? • 2 Phases of Digestion • 4 Components of Digestion • The Organs of Digestion

3. Introduction to the Digestive System • The digestive system is an organ system that ingests food, breaks it down into smaller chemical units, and absorbs the nutrient molecules.

4. What is Digestion? • Digestion is the mechanical and chemical breakdown of food into molecules small enough for the body to absorb.

5. 2 Phases of Digestion • Physical Digestion – begins in the mouth where the food is chewed • Chemical Digestion – occurs in the mouth and the stomach

6. 4 Components of Digestion • Ingestion – the intake of nutrients • Digestion – the breakdown of organic molecules • Absorption – the transport of digested nutrients to body tissues • Egestion – the removal of materials from food that the body cannot digest

7. The Organs of Digestion

8. Mouth • Physical digestion begins • Food is chewed into a bolus and mixed with saliva • Initial carbohydrate digestion

9. Esophagus • Peristaltic contractions move the food from the mouth to the stomach through the esophagus.

10. Stomach • Food storage • Initial protein digestion

11. Small Intestine • Site of the majority of digestion and absorption • Digestion of proteins, carbohydrates, and lipids • Villi increase surface area of small intestine for absorption

12. Pancreas • Releases enzymes into the small intestine to aid in digestion

13. Liver • Produces bile salts which emulsify fats • Storehouse for glycogen and vitamins • Detoxifies many substances in the body

14. Gall Bladder • Stores bile salts

15. Large Intestine • Stores food wastes long enough to reabsorb water • Houses bacteria which use waste materials to synthesize vitamins

16. Credits • Nelson Biology, Bob Ritter, Nelson Canada, 1993. • http://www.bayerpharma-na.com/children/RON/digest/chrd0106.asp • http://central.vislab.usyd.edu.au/gallery/vrml/tour/ingal/cyber_anatomy/HTML/gallBladder.html • http://health.upenn.edu/~surgery/clin/gi/gallblad.html • http://www.digestivedisorders.org.uk/leaflets/pancreax.htm • http://www.mts-stl.org/kw.organ.smintestine.phtml • http://www.ama-assn.org/insight/gen_hlth/atlas/newatlas/digest.html