Digestive System 2. 8th Grade lesson

 Hey everyone. Here is the second lesson in row of Digestion module. Enjoy!

Learning outcomes (to be able to):

Content: to be able to explain function of stomach, small intestine, large intestine, liver and pancreas.

Language: describe the flow of food through the digestive system using words: previously, next, before (this), afterwards, after (this), then.

Exercise 1. Step one (individual work). Circle the right words or phrases in italics to create grammatically correct questions by content.

 

Step two (individual work). Match the following correct answers to the questions above. There are two extra answers that cannot be used.

1.      The organs of the alimentary canal are the mouth, pharynx, esophagus, stomach, small intestine, and large intestine.

2.      The accessory digestive structures include the teeth, tongue, salivary glands, liver, pancreas, and gallbladder.

3.      They also contract in a peristaltic rhythm - contract in waves.

4.      Stomach glands secrete two digestive substances: enzyme pepsinogen and hydrochloric acid.

5.      The acid converts pepsinogen into pepsin, an active enzyme pepsin breaks down complex protein molecules.

6.      Break down of sugars, proteins and fats happen in your small intestine.

7.      This steady contraction and relaxation is called peristalsis.

Exercise 2. Step one (individual work): Before you start, go back to the exercise 2 and remember what you already know. Fill in the blanks by using given words and phrases:

absorption              activities                 small intestine                   digestion process    stomach and small intestine                  proteins                  mouth           enzymes       defecation               reflex                      back and forth

(A)____, fats and sugars are digested in different parts of the digestive system. Proteins are digested in the (B)____. Digestion of fats starts in mouth and is completed in (C)____. Digestion of carbohydrates mostly happens in the intestine but begins in a (D)____. Enzymes designed only for the digestion of particular type of food play important role in the (E)____.

The small intestine is where digestion is completed and almost all (F)____ happens. These two (G)____ are made by microvilli. There are around 200 million microvilli per square millimeter of small intestine, which contain special (H)____ that complete the digestion of sugars and proteins. Segmentation (division of something into smaller parts) moves the chyme (I)____, increasing mixing and opportunities for absorption.

The large intestine absorbs water and forms feces, and is responsible for (J)____. Bacterial flora break down rest of the sugars, and synthesise certain vitamins. The entry of feces into the rectum activates the defecation (K)____.

Step two (pair work): Check your results with your partner’s results.

Step three (individual work): Compare your results with the correct answers shown by your teacher.

Exercise 3. Step one (individual work): Compare small and large intestines. Write down common things in the middle.

Step two (pair work): Compare your results with partner’s results.

Exercise 4. Step one (individual work). Answer the given questions.

1.      Of the three major food classes (carbohydrates, fats, and proteins), which is digested in the mouth, the stomach, and the small intestine?

2.      Offer a theory to explain why segmentation occurs and peristalsis slows in the small intestine.

Step two (individual work). Discuss your answers with the face partner and class.