The Digestive SystemThe Digestive System

Grade 11 Biology

Table of ContentsTable 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 Introduction to the Digestive SystemDigestive 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?What is Digestion?

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

2 Phases of Digestion2 Phases of Digestion

1. Physical Digestion – begins in the mouth where the food is chewed

2. Chemical Digestion – occurs in the mouth and the stomach

4 Components of 4 Components of DigestionDigestion

1. 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

The Organs ofThe Organs of

Digestion

MouthMouth

Physical digestion begins Food is chewed into a bolus and mixed with

saliva Initial carbohydrate digestion

EsophagusEsophagus

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

StomachStomach

Food storage Initial protein

digestion

Small IntestineSmall Intestine

Site of the majority of digestion and absorption

Digestion of proteins, carbohydrates, and lipids

Villi increase surface area of small intestine for absorption

PancreasPancreas

Releases enzymes into the small intestine to aid in digestion

LiverLiver

Produces bile salts which emulsify fats

Storehouse for glycogen and vitamins

Detoxifies many substances in the body

Gall BladderGall Bladder

Stores bile salts

Large IntestineLarge Intestine

Stores food wastes long enough to reabsorb water

Houses bacteria which use waste materials to synthesize vitamins

CreditsCredits

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