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The Pigestive System

How does the body take what it needs from food? The body gets its raw materials from food by the process of digestion. Digestion is the breaking down of food into nutrients.

Your digestive system provides the nutrients your cells need to produce energy. To provide nutrients, the digestive system performs two functions. The first is to break food into nutrients. The second is to get the nutrients into the blood. Then the circulatory system transports them to your cells. Body cells use the nutrients to produce energy. The part of the food that the body cannot use is removed from the body. How does food travel through your body?

Mouth

Stomach

Large Intestine

Small Intestine

The Digestive System Your digestive system is like a long tube.

As food moves through the tube, it is changed by different organs. First, some organs grind up the food. Then, others change it by mixing it with chemicals. Next, other organs move the nutrients from the food into the blood. Finally, the unused part of the food is sent out of the body. The main organs of the digestive system are the mouth, the stomach, the small intestine, and the large intestine.

Food enters your body through your mouth. As your teeth grind up the food, it mixes with a liquid called saliva. Saliva contains a chemical that can change starch into sugar. Once the starch in your food has become sugar, it can pass into the blood. Then the body can use the sugar to make energy. When food leaves your mouth, it is still not completely digested. More starch needs to be changed into sugar. Proteins and fats have to be broken down. Digestion continues in the stomach.

# Answer these questions.

1. What are the two functions of the digestive system?

2. What are the four main organs of the digestive system?

3. What is saliva?

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Health, Nutrition, and RE. 5-6, SV 1419023608

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Vgesffon Continues a^xaoca^xBo^»ocao^»^»<pq>ci>CD<ad^»io<a^ai^>^»^9e»^a«^)caoca^aca^9^

When you swallow, food passes through the esophagus, a long tube that leads to the stomach. Gastric juice, produced by the stomach, contains acid and chemicals that break down proteins. Stomach muscles act like a blender to mix the food. By the time the food leaves the stomach, it has become a liquid.

Mouth

Esophagus.

Next is the most important step of digestion. The partly digested food moves from the stomach into the small intestine. The small intestine is like a hose. If it were stretched out straight, it would be about 20 feet long. As food moves slowly along this "hose," its nutrients pass through the walls of the small intestine. Nutrients diffuse through the villi, projections sticking out of the walls of the small intestine, into the blood. Then the blood carries the nutrients to every cell in the body.

Liver,

d

Gallbladder-

Stomach

Pancreas

Large Intestine

Small Intestine

The Digestive System

The process of digestion is helped by other organs. The liver andithe gallbladder pump chemicals into the small intestine. These chemicals h^pbreaki down fats. The pancreas pumps in other chemicals. These chemicals breakdown fats as well as proteins and starches. When too much sugar is produced during digestion,! the body has to store it. This is another job of the liver. It stores sugar that the body does not need.

Eventually, the food that is left passes out of the small intestine. From the small intestine, undigested food passes into the large intestine. There, water and minerals diffuse into the blood, and wastes are removed from the body.

^ Darken the circle by the answer that best completes the sentence.

1 FnnH travels from the mouth to the stomach through the 1 @ gallbladder

1. Food travels from the mouth to the stomach throi^h the 1 ® small intestine ® large intestine '(§) esophagus

2. The stomach produces ® orange juice ® gastric juice

to break down proteins. '•© ipancreas

3. In the small intestine, nutrients pass through _— i into! the blood. (A) blood gates ® gastric juice '© ihoses

4. The stores sugar the body does not need. ® liver (D stomach © ipancreas

@ sugar

@ villi

(B) gallbladder

www.harcourtschoolsuppiy.com © Harcourt Achieve Inc. All rights reserved.

36 Unit 1: Health

Health, Nutrition, and RE. 5-6, SV 1419023608