WHAT IS DIGESTION?
Digestion takes place in a number of steps. There are several organs in the body that help in digestion. Together, these organs make up your digestive system.
THE DIGESTION PROCESS
Digestion Starts in the Mouth When you chew your food, your teeth break the food down into smaller pieces. The sharp front teeth help to bite and cut the food into smaller pieces. The flat back teeth help to grind the food into a paste.
Saliva is a digestive juice that is found in the mouth. It is made by the salivary glands. When you chew, your tongue helps to mix the saliva with the food. This softens the food, so that it can be swallowed easily.
You have learnt in the previous lesson that food contains starch. Starch is an insoluble¹ substance. Saliva helps to break down the starch into soluble² sugar. When food that is rich in starch, like bread, you eat you will notice that it tastes sweet after you chew it. This is because the starch is being changed into sugar.
Your tongue then helps to push the food into a thin, long tube called the food pipe.
Digestion in the Stomach
The food passes into the stomach through the food pipe. The stomach is a bag-like organ. The stomach muscles churn³ the food with more digestive juices. These juices start to break down proteins and fats into simpler substances. The food remains in the stomach for up to three hours.
Digestion in the Small Intestine
From the stomach, the food passes into the small intestine. The small intestine looks like a long, coiled tube. The inner walls of the small intestine produce certain juices. Other organs such as the liver and pancreas also produce juices, which are poured into the small intestine. The food mixes with these juices and is completely digested.
The digested food is now in a simple, soluble form. It is absorbed into the blood through the walls of the small intestine. The blood then carries the digested food to all parts of the body. The digested food is used to produce energy.
Undigested Food
Some parts of food cannot be digested by your body. They pass into a pipe-like organ called the large intestine. Water from the undigested food is absorbed by the large intestine. The solid waste that remains passés out of your body through the opening called the anus.
Do you know : The digestive system is about 9 metres long, and the journey of food through it takes 20 to 30 hours.
GOOD EATING HABITS
You already know that you should eat a balanced diet and drink plenty of water. You also know that you must wash your hands well with soap and water before you eat. Here are some more rules to follow.
• Eat your food at fixed times.
• Never be in a hurry to finish your food. Chew your food properly before swallowing it.
This makes the digestion of food much easier.
• Rinse your mouth thoroughly after eating.
• Rest a while after eating. Your body needs oxygen to digest the food.
If you start playing, the other organs will use up the oxygen and stomach ache. you may get a stomach ache.
Eat lots of vegetables and fruits. Besides nutrients, they also have roughage or fibre. Your body cannot digest fibre.
But fibre helps to remove waste from your body.
Now You Know...
The breaking down of food into small, simple substances is called digestion.
Food has to be digested before it can be used by the body to give you energy.
Digestion takes place in the digestive system of your body.
Digestion starts in the mouth; continues in the stomach and is completed in the small intestine.
Digested food is absorbed into the blood through the walls of the small intestine.
Undigested food passes out of the body through the anus.
You should have good eating habits.
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