List, in order, the three functions of the digestive system (what is food doing…).

1. Class opener: On a clean piece of paper (Heading (20), without using your book, notes, or neighbor… • List, in order, the three functions of the digestive system (what is food doing…).

2. Prime Time Answers : Functions • Break down food into molecules the body can use. • Absorb the food molecules into the blood. • Eliminate wastes from the body.

3. I. Types of Digestion: • Mechanical – foods are physically broken down into smaller pieces • Chemical – chemicals produced by the body break foods into smaller chemical building blocks • Both begin in the mouth.

4. II. The Process of Digestion • The Mouth • Mechanical Digestion • Teeth cut food into bite-size pieces, then crush and grind them into smaller pieces. • Saliva mixes with and moistens the food as you chew to aid you in swallowing. • Chemical Digestion • Saliva contains chemicals called enzymes which are proteins that speed up chemical reactions in the body. • The enzymes break down starches into sugar molecules.

5. B. Esophagus • A muscular tube that connects the mouth to the stomach. a. It’s lined with mucus, which allows food to move easily through the esophagus. • At the top of the esophagus, there is a flap of tissue called the epiglottis. It covers the opening to your trachea (windpipe) when you swallow so that you don’t choke on your food. a. Food remains in the esophagus for about 10 seconds. b. After food enters the esophagus, contractions of smooth muscles push the food toward the stomach. (Peristalsis)

6. Prime Time: On assignment # 23 answer the following: (without using your book, notes, or neighbor…) • 1. List and describe the 2 types of digestion. • 2. Describe the process food goes through in the mouth. • 3. Describe what the esophagus looks like. • 4. What happens to food in the esophagus?

7. Primetime Answers: • 1. Mechanical- food is physically broken down. Chemical- chemicals in the body break down food. • 2. Mouth: Mechanical-teeth cut food down and saliva moisten its. Chemical- Saliva has enzymes that break down the starches. • 3. Esophagus is a muscular tube that is lined with mucus. It has a flap called the epiglottis that blocks food from entering the trachea. • 4. Using the process called peristalsis food is pushed down to the stomach.

8. Stomach • A J-shaped, muscular pouch located in the abdomen. • Most mechanical digestion and some chemical digestion • Mechanical – Three strong layers of smooth muscle surround the stomach and contract to churn the food. This mixes it with fluids that further the digestion process. • Chemical – The churning of mechanical digestion mixes the food with strong enzymes that continue to break down food. • Hydrochloric acid (HCl) in your stomach, provides the ideal environment for the enzymes for proteins to work. • Food remains in the stomach for about three hours. When it is a thick liquid, it is ready to move to the next section of the digestive system.

9. On heading 3, answer the following questions about the stomach model. Please use complete sentences: • What do you observe happening inside the bag? • In the model, what did the hands represent? • What did the water and food coloring represent? • How did the churning motions of the stomach muscles help with digestion? • If food were not broken into smaller pieces in the mouth, what do you think would happen in the stomach?

10. Prime Time: On assignment # 7 answer the following: (without using your book, notes, or neighbor…) • List the three functions of the digestive system in order. • Describe the stomach (made of, looks like, etc.) • Describe mechanical digestion in the stomach. • Describe chemical digestion in the stomach. • Where does the most mechanical digestion take place? • What is the name of the acid in the stomach? • What do the enzymes in the stomach primarily digest? • How long is food in your stomach?

11. Primetime Answers: • Functions: • Break down food into molecules the body can use. • Absorb the food molecules into the blood. • Eliminate wastes from the body. • The stomach is a j-shaped pouch made of 3 layers of smooth muscle. It is lined with mucus. • The smooth muscle churns and grinds the food into smaller pieces. • The acid in the stomach activates enzymes to chemically digest the food.

12. Most mechanical digestion takes place in the stomach. • The acid in the stomach is hydrochloric acid (HCl). • The enzymes in the stomach primarily digest proteins. • Food is in your stomach for about 3-4 hours.

13. Small Intestine • The part of the digestive system where the most chemical digestion and absorption of nutrients takes place. • The digestion of fats takes place here. • Several secretions get added here from other organs. (Liver and Pancreas) • The small intestine is lined with millions of tiny projections (villi) that help increase the surface area for the absorption of nutrients from your food.

14. Liver • The role of the liver in the digestive system is to produce bile • Bile is a substance that breaks up fat particles. It is not an enzyme, but it does break up large fat molecules into small fat droplets which can be broken down easier. • Bile is stored and concentrated in the gallbladder.

15. Pancreas • The pancreas produces enzymes that flow into the small intestine and help break down starches, proteins, and fats. • It also produces insulin which regulates the amount of sugar in your blood.

16. Class opener, answer the following(no notes, no books, no neighbors): • Where does the most mechanical digestion take place? • Where does the most chemical digestion take place? • What is the liver’s job? • What do the enzymes in the stomach primarily digest? • What do the enzymes in the mouth break down? • What does the small intestine digest? • What are the tiny projections that line the small intestine called? What is their function? • What is bile? • Where is bile stored?

17. Answers: • Most mechanical digestion happens in the stomach. • Most chemical digestion happens in the small intestine. • The liver’s job is to make bile. • The enzymes in the stomach digest protein. • The enzymes in the mouth digest starches/carbohydrates.

18. The small intestine is where fat digestion takes place, however all nutrients are digested in the small intestine. • The tiny projections inside of the small intestine are called villi. Villi increase the surface area to absorb more nutrients. • Bile is a chemical made by the liver that breaks down fat molecules into smaller fat molecules. • Bile is stored and concentrated in the gallbladder.

19. Large Intestine • The large intestine is the last section of the digestive system. • The large intestine contains bacteria that feed on materials as they pass through. Many of them make vitamins like vitamin K. • Water is absorbed from the digested food materials into the bloodstream. • The large intestine ends in a tube called the rectum, which is where wastes are compressed into solid form.