1. The Digestive System Coachbook, pages 67-68

2. Getting the Idea:
The nutrients your cells use to produce energy come from the food you eat. Breaking food down for energy also produces wastes. Those wastes must be removed from the body.

3. Two of your body systems break food down into usable forms and remove wastes products from your body.

4. The Digestive System
The digestive system is the group of organs that break food down into molecules that are small enough to be absorbed by and transported throughout the body.

5. The Mouth
Digestion begins in the mouth as your teeth grind, crush, and break apart your food. Breaking food into smaller pieces is known as
mechanical digestion.

6. As you chew your food, your tongue moves the food around and mixes it with saliva. Saliva moistens the food so it is easier to swallow. Saliva also contains an enzyme that begins to break down starches and sugars. An enzyme is a protein that speeds up a chemical reaction.

7. When food has been chewed enough, it is moved to the back of the mouth for swallowing.
After food is swallowed, it passes the epiglottis, a flap of tissue that covers the opening of the trachea to keep food out.
The food then moves into the esophagus.

8. The Esophagus
The esophagus is a muscular tube that connects the mouth to the stomach.
Contractions of the muscles in the wall of the esophagus push the food toward the stomach. These contractions are called peristalsis.

9. Mouth and Esophagus Mouth Esophagus
Teeth - break up the food. (Mechanical Digestion)
Saliva- chemical in the mouth that begins digestion. (Chemical Digestion)
Esophagus
Tube that connects the mouth to the stomach.

11. The Stomach
The stomach is a muscular organ. It continues mechanical digestion by contracting and squeezing its contents. Glands in the stomach produce enzymes and acids that continue to break food molecules apart through chemical digestion.

13. Dinosaur Stomach

14. Small Intestine
Food remains in the stomach for several hours!!
The stomach digests the food into a liquid. This liquid then enters the small intestine, a long, muscular tube where the body absorbs nutrients from food.

16. The Pancreas
The pancreas is a gland that releases digestive enzymes and other chemicals into the small intestine.
Some of these substances neutralize stomach acids, which would otherwise damage the lining of the intestine and prevent enzymes from doing their job.

17. The Liver
The liver also helps with digestion in the small intestine.
The liver is an organ that makes bile, a liquid that helps to break down fat.

18. The Gall Bladder
The bile produced by the liver is temporarily stored in the gall bladder.

19. Absorption in the Small Intestine
Once food is digested, nutrients are absorbed through the walls of the small intestine.
The walls of the small intestine have many folds called villi, which increase the surface area that can absorb digested food.

20. Villi greatly increase the surface area of the small intestine.
Laid out, it would be equal to the surface of a tennis court.

21. Villi
Nutrients enter the bloodstream through the capillaries in the villi. The blood then transports the nutrients to all the cells of the body.
Any undigested material left in the small intestine is moved by peristalsis into the large intestine.

22. Peristalsis
Waves of muscle contractions that pushes food through the digestive tract.

25. The Large Intestine
The large intestine is an organ of both the digestive system and the excretory system. Its role in digestion is to absorb water from the undigested material.
The large intestine also compacts the solid wastes that remain from undigested food.

26. The Large Intestine continued…
The remaining material is ready for elimination from the body.
Rectum- a short tube that is the last portion of the large intestine.
Waste material is pressed into a solid form.
Waste material exits through the anus, a muscular opening at the end of the rectum.

27. Rectum
Opening
And
Closing

28. Mouth
Esophagus
Liver
Pancreas
Stomach
Large
Intestines
Small
Intestines
Rectum

29. Digestion
Drying
Absorption