1. 3.2 The Digestive System

2. Digestive System The digestive system has 4 primary functions:
Ingestion
Digestion
Absorption
Egestion
IDEA Acronym

3. Ingestion & Egestion
Ingestion refers to the consumption of a substance (1st step).
Egestion refers to the removal of unwanted materials from the body. (Last step)

4. Digestion
Digestion is the mechanical and chemical breakdown of food into smaller components. (2nd step)
It is the breakdown of large food molecules into smaller ones.
Fat
Proteins
Carbohydrates
Waste

5. Absorption (Fig. 3.16, pg. 98) Body (Through Blood Vessels)
Absorption is the process by which digested food nutrients and water are taken from the intestine and moved throughout the body. (3rd step)
Body (Through Blood Vessels)
Draw image to show this
Body (Through Blood Vessels)

6. Digestive System Labelled
Pancreas
Gallbladder

7. Scenario: Eating a Burger
The burger enters the oral cavity (i.e. the mouth)
A bite is taken out of the burger and chewing proceeds (mechanical digestion)
The salivary glands secrete amylase to breakdown the carbohydrates. (chemical digestion)
Once the food has been broken down into small enough pieces, the food is swallowed.

8. Down the esophagus to the Stomach
The partly digested food travels through the pharynx (throat) down the esophagus through peristaltic contractions.

9. Digestion in the Stomach
The food passes through a sphincter into the stomach where gastric juices surround the food.
Hydrochloric acid and the enzyme pepsin break down most of the protein. (chemical digestion)
The stomach then covers the food in mucus and sends the food down to the small intestine (duodenum)

10. The Small Intestine
The pancreas, liver, and gall bladder release chemicals to help break down the food further.
The small intestine contains millions of tiny folds called villi and microvilli
Provides increased area for absorption
Nutrients and water can be reabsorbed into the bloodstream

12. The Large Intestine Includes the colon, rectum, and anus
Mainly absorbs water
Also absorbs vitamins and various salts
Undigested food leaves as feces (E.g. Corn)

13. Complete “Digestive System” Worksheet
Read pg
Complete “Digestive System” Worksheet
Do # 1 – 4 on pg. 99
IT TAKES GUTS