1. Word Wall Physical & Chemical Digestion
7th Gr Science

2. Chemical Digestion
Involves enzymes that break down starches, proteins, and fats.
Each type of molecule is broken down into its simplest part through the use of enzymes.

3. Enzymes

4. Chemical Digestion of Starch

5. Chemical Digestion of Protein

6. Chemical Digestion of Fats

7. Physical Digestion
Requires the use of energy and the mechanical breaking down of food.

8. Digestion - in the Mouth

9. Peristalsis
Involuntary waves of muscle contraction that keep the food moving along in one direction through the digestive system.
Important points: 1/ Peristalsis does not only happen in the esophagus, it happens all along the digestive tract, from
the mouth to the anus.
2/ In the stomach and in the intestine, peristalsis has a very important role in mixing the food with digestive juices.

10. Digestion in the Stomach

11. Digestion in Small Intestines – 1st
In the duodenum, the bile produced by the liver as well as the enzymes produced by the pancreas are released in the alimentary canal and they will mix with the food.

12. Digestion in Small Intestines – 2nd
After the duodenum, in the rest of the small intestine
The final steps of digestion take place in the small intestine:
- breaking of insoluble substances into soluble ones
- absorption of nutrients into the blood stream by diffusion