1. What Happens to Food Once it Enters Your Mouth?

2. Digestion – the process that breaks down food into small molecules that can be absorbed and moved into blood.
Mechanical Digestion: takes place when food is chewed, mixed, and churned.
Happens in the mouth, esophagus, and stomach.
Chemical Digestion: takes place when chemical reactions break down large food molecules into smaller ones.
Happens in the mouth, stomach, small intestine.

3. Enzymes Proteins that speed up reactions without being used up.
Enzymes are very
important to the
digestive process.

4. Organs of the Digestive System
Digestive Tract – mouth, esophagus, stomach, small intestine, large intestine, rectum, anus. All food passes through these organs.
Accessory Organs – tongue, teeth, salivary glands, liver, gall bladder, and pancreas. Liver, gall bladder, and pancreas make and store enzymes.

5. The Mouth – both mechanical and chemical digestion happen here.

6. The Esophagus About 25 cm long.
Takes about 4-10 seconds for food to reach the stomach.
Peristalsis moves food down the esophagus.
No digestion occurs here.

7. The Stomach Mechanical and chemical digestion happen here.
Hydrochloric acid and enzymes break down food and kill bacteria.
Food leaves in 2-4 hours as a thin, watery liquid called chyme.

8. The Small Intestine About 4-7 m in length.
Many enzymes are mixed with food here.
Covered with villi to increase surface area.
Food molecules are absorbed here and released into the bloodstream.

9. Small Intestine and Villi

10. Large Intestine
Main job is to absorb water back into the body from chyme.
Peristalsis slows down here meaning food stays for up to 3 days.
Semi-solid wastes are released by the rectum and anus.

11. Bacteria Are very important to the digestive process.
Feed on undigested material in large intestine.
Produce vitamins.
Also produce gas.

12. Digestive System Chemical and physical digestion.
Ingestion happens in the mouth; digestion occurs in the mouth, stomach, and small intestine; absorption occurs in the small and large intestine.
Accessory organs move and cut up food and supply enzymes and other chemicals.
Large intestine reabsorbs water.

13. One last look…