Lesson 3.1: Digestive System

Your body cannot use the foods you eat without first changing them.  For example, you need the mineral iron, but you cannot eat an iron nail and get your iron needs.  Your body cannot use the iron in that form. In fact, your body cannot convert the iron nail into a useable form at all.  The iron that your body needs must be in a form that it can absorb.  Iron(II) sulphate is a common form found in mineral supplements.  The body system that changes food you eat into forms that your body needs is the digestive system. 

Read Digestive System: Mining the Nutrients on page 207 of your textbook. Then, answer the following questions.

 

Question 1. What is the function of your digestive system?

Question 2. What are the three processes that are involved in digestion, and what things are involved in each?

Question 3. Explain the role of the first part of the digestive system, the mouth.

Question 4. What liquid is in the stomach and breaks down food?

Question 5. What is the function of enzymes in the stomach?

Question 6. The stomach is often thought of as a chemical digester because of strong stomach acids.  For what other form of digestion is the stomach responsible?

Question 7. What is the form of the food when it leaves the stomach?

Question 8. How did Dr. William Beaumont show that gastric juices will turn solid meat into a liquid? 

 

Check your answers with those that follow.

 

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. What is the function of your digestive system?

The function (or job) of your digestive system is to break up the food you eat and obtain the necessary nutrients.

Question 2. What are the three processes that are involved in digestion, and what things are involved in each?

The three processes are

        • mechanical digestion: teeth and stomach break food into small pieces
        • chemical digestion: enzymes break food into smaller pieces
        • absorption:  products of digestion move into the bloodstream

Question 3. Explain the role of the first part of the digestive system, the mouth.

The mouth is where food first enters the digestive system.  Teeth in the mouth cut and grind food into small pieces.  The mouth has special glands that produce saliva that contains enzymes to break starch into smaller parts such as glucose (sugar).

Question 4. What liquid is in the stomach and breaks down food?

The liquid in the stomach is gastric juice.  It is often called stomach acid.  This is not actually correct because the gastric juice also contains enzymes.

Question 5. What is the function of enzymes in the stomach?

The function of enzymes in the stomach is to break down proteins and other food particles.

Question 6. The stomach is often thought of as a chemical digester because of strong stomach acids.  For what other form of digestion is the stomach responsible?

The stomach is also responsible for mechanical digestion.  It churns the food using stomach muscles and completes mechanical digestion.

Question 7. What is the form of the food when it leaves the stomach?

When food leaves the stomach, it is in liquid form.

Question 8. How did Dr. William Beaumont show that gastric juices will turn solid meat into a liquid?

In Off the Wall on page 207, a story is told about a trapper who shot himself in the stomach.  He recovered, but was left with a hole in his abdomen that provided direct access to the inside of his stomach.  When Dr. Beaumont added some of the gastric juices from the stomach to some meat, the meat began to turn to a liquid.

 


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