Page 96 - Science and Technology Std 3

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Parts of the digestive system
The digestive system is made up of the mouth, oesophagus,
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stomach, liver, pancreas, gall bladder, small intestine, large
intestine, rectum and anus. Each part of the system has its
function.

Digestion in the mouth

Digestion starts in the mouth. Once food enters the mouth, it
is mixed with saliva and chewed using the teeth. The food is
then swallowed through the oesophagus to the stomach. The
oesophagus is also called the gullet.

Digestion in the stomach
In the stomach, food is stored temporarily. The food is digested

to form a thick liquid. The walls of the stomach produce an acid.
The acid helps in the digestion of food. It also kills germs in the
food. Before the food enters the small intestine, the gall bladder

releases bile. Bile helps in the digestion of food. Also, the pancreas
releases enzymes which help in the digestion of food.

Digestion and absorption in the small intestine

All types of food are digested in the small intestine. The
digested food in form of nutrients and minerals are absorbed
by the small intestine. These enter the body.

Absorption in the large intestine

The large intestine absorbs water and minerals from the
remaining food residue. The food residue moves down to the
rectum. Then, it is removed from the body through the anus in

the form of faeces.

The importance of the digestive system

The digestive system is important for breaking down food into
nutrients. Such nutrients are used by the body for energy and
growth.

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PROPERTY OF UNITED REPUBLIC OF TANZANIA GOVERNMENT
Ministry of Education, Science and Technology
Science and Technology 3.indd 89 03/08/2019 11:02