The Digestive System Grade 11 Biology Table of

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 l 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? l 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 2. Chemical Digestion – occurs in the mouth and the stomach 1.

4 Components of Digestion Ingestion – the intake of nutrients 2. Digestion – the breakdown of organic molecules 3. Absorption – the transport of digested nutrients to body tissues 4. Egestion – the removal of materials from food that the body cannot digest 1.

The Organs of Digestion

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

Esophagus l 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 l 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 l 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. bayerpharmana. com/children/RON/digest/chrd 0106. asp http: //central. vislab. usyd. edu. au/gallery/vrml/tour/ingal/cy ber_anatomy/HTML/gall. Bladder. 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. amaassn. org/insight/gen_hlth/atlas/newatlas/digest. html