Download Study Guide: Digestive System a. Breaks food into molecules the

Name___________________________________
Period________
Study Guide: Digestive System
Directions: Read pg. 382-393
1. What are the three functions of the digestive system?
a. Breaks food into molecules the body can use.
b. Molecules are then absorbed into the blood
and carried throughout the body.
c. Wastes are eliminated.
2. What is “digestion”?
The process by which your body breaks down food into nutrient molecules.
3. What is the difference between “digestion” and “absorption” in the digestive process?
Digestion is the breaking down of food into small particles (molecules); absorption is
the process by which these molecules move into the bloodstream.
4. The digestion of food begins in the mouth. Identify and describe the two types of digestion that
occur in this location.
a. Mechanical- physically breaks down food into smaller pieces.
b. Chemical- chemically breaks complex molecules into smaller molecules.
5. Where is saliva produced? What is its function in the digestive process?
Saliva is produced by the salivary glands in the mouth. It moistens food and breaks
down starches (amylase).
6. What is the role of enzymes in your body?
Enzymes are proteins that speed up chemical reactions.
7. Step 1: The food travels from the mouth into a tube called the esophagus.
8. What is peristalsis?
Contractions of smooth muscles- waves of muscle contractions that pushes food.
9. Step 2: Food enters the stomach.
The stomach is made of 3 layers of involuntary (voluntary or involuntary) muscle.
Name___________________________________
Period________
10. What is the function of the stomach?
The stomach breaks down food by churning the food and producing gastric juices.
11. Which two chemicals help digest food in the stomach?
Pepsin and hydrochloric acid
12. How long does food remain in the stomach? 2 to 4 hours
13. Study Figure 12 on page 386. Which enzymes aid in protein digestion?
Pepsin, trypsin, and peptidase
14. Step 3: Food enters the small intestine. The small intestine has two functions in the digestion of
food
a. First, the small intestine continues the chemical breakdown of nutrients into smaller
molecules. How do the liver and pancreas help in this digestion?
Liver- produces bile which breaks down fats
Pancreas- produces enzymes that help break down starches, proteins, and fats.
b. Second, the nutrient molecules move into the blood vessels so that the nutrients can be
carried to all the cells in the body. This occurs in the villi of the small intestine. This
movement is the process of absorption.
15. Step 4: The undigested food moves into the large intestine.
What is the function of this organ? It absorbs water from undigested food. It holds the
undigested food until it is eliminated from the body.
16. What internal stimulus causes vomiting? Explain how vomiting can be helpful to the body.
Irritation of the digestive system causes vomiting. It is helpful because it can remove
harmful materials from the body.
Thinking Critically
Some people are allergic to a protein in wheat. When these people eat foods made with wheat, a reaction
destroys the villi in the small intestine. What problems would you expect these people to experience as a
consequence of this reaction?
Without villi, the body cannot absorb nutrients into the bloodstream.