Page 18 - Science Class 07

Tongue

There is a flat muscular organ present inside
our mouth called tongue. It is a ached with The largest number of pa ents suffer from
dental diseases. It is because, people
the lower surface of the mouth at one end.
generally ignore the proper way of keeping
More than half part of the tongue is free to
teeth clean. Those who eat much chocolates
move. It can also be stretched or relaxed.
suffer from dental plaque. Sugar le in the
It has the following func ons: mouth produces acids which harm the
v It helps us to move food inside our mouth. enamel. This way lead to toothache, bad
v It also helps in mixing of food with saliva. breath, etc.

v It rolls the food into a ball and pushes it
into the oseophagus.
v It has four dis nct types of taste buds 1. Why are human beings called
which help us to taste the food. It tells us heterotrophs?

whether the food is salty, sour, sweet or 2. What is absorp on?
bi er. 3 What are func ons of different glands
v It also helps us to speak. located in our body?
Salivary Glands 4. What are different types of teeth?
5. Write any two func ons of tongue.
A salivary gland is a ssue in our mouth that
expels saliva. Any me our mouth comes near a 6. What is oesophagus?
hot sandwich we feel them ac vate. As Stomach
exocrine glands, they expel saliva onto the
Stomach is the diges ve organ that is located in
epithelial surface of our mouth by way of
the upper abdomen, under the ribs. The upper
ducts. Each day, our glands produce as much as
part of the stomach connects to the esophagus,
a quart of saliva.
and the lower part leads into the small
Oesophagus or Food Pipe intes ne. When food enters the stomach,

A wide muscular tube of about thirty cm long muscles in the stomach wall create a rippling
which connects mouth mo on (peristalsis) that mixes and mashes the
cavity and stomach is food. At the same me, juices made by glands
called oesophagus or in the lining of the stomach help to digest the
food pipe. When we food. A er about 3 hours, the food becomes a
swallow food, it reaches liquid and moves into the small intes ne,
stomach through the where diges on con nues.
oesophagus. The inner
wall of the oesophagus

show a wavy movement
called peristalsis. This
movement is caused
due to the muscle
contrac on. The View of Oesophagus
Stomach
18 Science-7