☰ Year plan · Science

Digestion begins

Week 4 · Chapter 3 Digestion: 3-1 Where Food Goes; 3-2 The Function of Saliva · 3 lessons
3

Digestive juices further down the tract

Science P6: Term 1, Chapter 3, pp. 24–29
GoalName the digestive juices along the tract and say what they do.
New words
stomach juice · a digestive juice made in the stomachpancreas · an organ that makes a digestive juice for the small intestinegall bladder · a small bag that stores bile from the liver
Explanation

The digestive tract has more than one digestive juice. After saliva, the stomach makes its own juice. The stomach squeezes the food and mixes it with the juice until it becomes a thick liquid. Then the food moves into the small intestine. Here more juices join: some from the pancreas and the gall bladder and some made by the small intestine itself. Each juice helps to break one kind of food into smaller pieces. We do not need the names of the substances inside the juices. We only need to remember that these liquids break food down. Most food is absorbed in the small intestine, not in the stomach. Next week we will see how.

WhereJuiceWhat it does
Mouthsalivastarts to break down starch
Stomachstomach juicehelps break down food
Small intestinejuices from pancreas, gall bladder and intestinefinish breaking food down
Worked examples
ricechickensalad
Marwan eats a meal of rice, chicken and salad. In the mouth, saliva starts with the rice. In the stomach, juice and squeezing break down the chicken. The small intestine finishes the job.
After a large meal, food stays in the stomach for a few hours. The stomach muscles squeeze and mix it until it is a thick liquid. Then small amounts move on.
Plain sugar is already made of small pieces, but starch in bread is made of long chains. The body must break starch down step by step before it can be absorbed.
Class activity

Juice map. Draw three boxes: mouth, stomach and small intestine. Under each, write the juice that works there. Draw arrows to show food moving. Add one food and tell what happens to it in each box.

Practice
1
Name the first digestive juice.
2
What does the stomach do to food besides using its juice?
3
Where is most food absorbed: the stomach or the small intestine?
4
Which organs send digestive juices into the small intestine?