CHAPTER 20. Digestive System

UNIT 5 SYSTEMS OF THE MAMMAL
P 4 TERM 3

Objectives: By the end of this topic pupils should be able to: 1. Label parts of the digestive system. 2. Describe the functions of the labelled parts. 3. Describe some good and bad food habits and how they affect our health. 4. Name types of teeth and their functions. 5. Label parts of the teeth. 6. Demonstrate ways of caring for teeth and ways of preventing tooth decay.

Behavioural Changes:

Pupils should:

1. Eat well cooked or ripe fruits.
2. Cut raw food (e.g. fruit & vegetable) into smaller pieces to make it easy for chewing.
3. Chew food properly.
4. Clean their teeth properly and regularly.
5. Avoid biting hard things which can damage their teeth.

Sub Topics:

a) Revision of the Digestive Systems, its parts and functions (done in Unit 5 Term 3).
b) Good and Bad Eating habits.
c) Teeth

- types of teeth
- false teeth
- care of teeth

Main Ideas:

1. Foods are introduced into the digestive system mainly through the mouth.
2. Each part of the digestive system has a specific function in the digestion of food.
3. It is important to care for each part to enable it to function properly.

Figure

Notes for the Teacher:

Most of the food we eat cannot be used by our bodies in the form in which we swallow it.

After chewing, food is swallowed to enable the digestive juices to act on it.

The body extracts the nutrients it needs for its repair, growth and energy.

GOOD EATING HABITS:

Activities:

To make sure your food gets digested properly, practise the following good eating habits.

1. Wash hands before eating to avoid germs and disease.
2. Eat small pieces of food to avoid choking.
3. Chew food properly to avoid stomachache and constipation.
4. Eat gently to allow food to be digested.
5. Talk when mouth is empty, not full of food.
6. Brush teeth twice a day, in the morning and at night before bed time.

DANGERS OF BAD EATING HABITS:

1. Too much food/big lumps swallowed can block the wind pipe and choke to death.

2. Eating hurriedly results in unchewed food being swallowed which can cause constipation and stomach aches.

3. Talking with a mouth full of food, you can bite your tounge, swallow unchewed food or too big a piece and choke.

4. Biting very hard things and opening bottles with your teeth can damage your teeth.

5. Too much alcohol can lead to liver disease, loss of appetite and less money for food.

SKILLS TO BE DEVELOPED:

Recording, Drawing, Labelling, Role playing, Writing, Describing, Reporting,

MATERIALS REQUIRED:

Paper, pencils, Teeth, tooth brushes, tooth paste. Empty glass, Bottle, Water.

TEETH

Notes for the Teacher:

Teeth are very important to our digestion. We need teeth for biting and chewing our foods. Children below the age of seven years have softer teeth called "milk teeth". They cannot bite/chew hard foods so most of their foods are mashed, minced or ground for them. From 7 years on, the milk teeth begin to fall off and new stronger teeth grow in their places.

These are adult teeth for ever, so we must take good care of them. Sweet foods and bits of foods stuck between teeth make them rot if not removed and washed away.

Rotten teeth are painful, smelly and ugly looking. Once a tooth gets a small hole in it, the hole will get bigger if not treated.

Figure

The hole fills up with more sweet foods which corrode the teeth further.

Foods which are most dangerous to teeth are all foods with sugar in them, like sweet drinks, sweets, bubble gum, biscuits even sugar - cane etc.

FALSE TEETH:

"False teeth" are sometimes taken out when a child has diarrhoea.

False teeth are actually not false. They are developing milk teeth in the gum. They should be allowed to grow properly.

If taken out, they cause infection and children sometimes die.

Taking out "False Teeth" does not cure diarrhoea or anything else. It is a dangerous practice and should never be carried out.

CARE OF TEETH:

Brush teeth twice a day, morning and night.

How to brush.

Brush in a circular method.

Figure

Type of brushes.

Commercial tooth brush

Things to use for tooth paste

Baking powder and salt.

Put some amount of salt to some amount of baking powder.

Don't use sand, as it damages tooth enamel.

Figure

Some Activities for Pupils:

Ask two children who are loosing their teeth to bring their fallen teeth.

Put one tooth in a bottle of coca-cola or water with sugar in.

Put the other tooth in a bottle of plain water.

Leave them there for about 3 days. Take and examine the two teeth. The tooth in the sweet drink will be going soft, you can scrape off bits of it with a knife. The tooth in water remains still strong and healthy.

Get pupils to record how many teeth they have. How many their older and younger sisters and brothers have. How many teeth their parents still have. Make a class chart of teeth by age.

Draw a diagram of the digestive system from the mouth to the anus showing the different parts.

· Get pupils to trace the diagram and with them label the mouth, teeth, stomach, liver, pancreas, small intestines, large intestines and anus.

· Role play on good eating habits.

· Ask class to collect pictures of foods as advertised in magazines, or foods themselves.

· Discuss the usefulness and origin of these foods.

· Teach children how to clean teeth properly. Let them make their own rhyme.

· Show different types of tooth brushes modern and the local sticks.

Show types of tooth paste. Discuss the advantages and disadvantages of the one they use.

· Examine pupils teeth for cleanliness and decay.

· Draw structure of tooth and label.

· Role play a visit to a dental clinic. If possible organise a visit to a dentist's clinic.

EVALUATION:

Observe if children brush their teeth correctly.

FOLLOW UP:

Observe whether pupils use good eating habits.

Record how many children have poor teeth Send them to a health worker.

TEST YOURSELF:

(What have you learnt from this chapter?)

1. Describe the functions of the:

a) Kidney
b) Liver
c) Stomach
d) Pancreas

2. Name the types of teeth and their functions.

3. List

a) three good eating habits.
b) three bad eating habits.

4. How should a teacher make sure that children prevent tooth decay and keep good teeth?