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The Digestive System. Grade 11 Biology. Table of Contents. Introduction to the Digestive System What is Digestion? 2 Phases of Digestion 4 Components of Digestion The Organs of Digestion. Introduction to the Digestive System.
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The Digestive System Grade 11 Biology
Table of Contents • Introduction to the Digestive System • What is Digestion? • 2 Phases of Digestion • 4 Components of Digestion • The Organs of Digestion
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.
What is Digestion? • Digestion is the mechanical and chemical breakdown of food into molecules small enough for the body to absorb.
2 Phases of Digestion • Physical Digestion – begins in the mouth where the food is chewed • Chemical Digestion – occurs in the mouth and the stomach
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
The Organs of Digestion
Mouth • Physical digestion begins • Food is chewed into a bolus and mixed with saliva • Initial carbohydrate digestion
Esophagus • Peristaltic contractions move the food from the mouth to the stomach through the esophagus.
Stomach • Food storage • Initial protein digestion
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
Pancreas • Releases enzymes into the small intestine to aid in digestion
Liver • Produces bile salts which emulsify fats • Storehouse for glycogen and vitamins • Detoxifies many substances in the body
Gall Bladder • Stores bile salts
Large Intestine • Stores food wastes long enough to reabsorb water • Houses bacteria which use waste materials to synthesize vitamins
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