Std 5 EVS 1 · Chapter 21

21. Busy at Work — our Internal Organs

Complete solutions to the Exercise. Maharashtra State Board (Balbharati), Standard 5 EVS 1.

Exercises

1What’s the solution? A person has fainted and a crowd of people has surrounded him.

Move the crowd back — the first need is fresh air. Ask the people standing round to step away and give the person space.

Lay the person down — make him lie flat in a safe, shaded place and raise his legs a little so that blood reaches the head.

Loosen tight clothing — open anything tight round the neck, chest and waist so that breathing is easy.

Check that he is breathing — look at the chest, listen and feel for the breath. Call his name loudly and tap his shoulder.

Call for help — if there is no response, send someone at once to call a doctor or an ambulance.

Stay calm beside him — when he comes round, do not let him get up suddenly, and do not give him anything to drink until he is fully awake.

2Use your brain power!

(a) Why do we sometimes choke suddenly while eating?

Two passages begin at the back of our throat — the food pipe and the windpipe. A small flap called the epiglottis closes the windpipe each time we swallow, so that food goes down the food pipe only.

If we eat in a hurry, do not chew properly, or talk and laugh while swallowing, the flap does not close in time. A little food then slips towards the windpipe, and we choke and cough until it is thrown out.

(b) How is the air that we inhale purified in our body?

Hairs in the nose — they trap dust and larger particles in the air we breathe in.

Moist lining — the sticky lining of the nose holds back finer dust and also warms and moistens the air.

Cilia in the windpipe — very fine hair-like parts lining the trachea move together and push trapped dust back up and out.

Only air that has been cleaned in this way reaches the lungs.

3Fill in the blanks.

(a) Oxygen gas is transported to all parts of the body.

(b) The stomach is like a bag.

4Match the following.

Group A	Answer
Lungs	Respiration
Stomach	Digestion
Heart	Circulation
Brain	Co-ordination

5Answer the following questions.

(a) Name the systems that carry out the different functions of the body.

Digestive systemBreaks down the food we eat so the body can use it.

Respiratory systemTakes in oxygen and gives out carbon dioxide.

Circulatory systemKeeps the blood flowing to every part of the body.

Nervous systemControls and co-ordinates the work of all the other systems.

(b) Describe how the exchange of oxygen and carbon dioxide gases takes place in the lungs.

The air we breathe in travels down the windpipe and reaches the tiny air sacs of the lungs called alveoli. Very thin blood vessels lie all around these air sacs.

Oxygen goes in — the oxygen in the air passes from the alveoli into the blood in these thin vessels, and the blood carries it to every part of the body.

Carbon dioxide comes out — at the same time, the carbon dioxide brought back by the blood from all parts of the body passes into the air inside the alveoli.

It leaves the body — when we breathe out, this carbon dioxide goes out along with the air.

Saliva is called a digestive juice because digestion actually begins with it, in the mouth itself. It contains substances that start breaking down the starch in our food into simpler sugars. It also moistens the food and makes it soft, so that the chewed food can be swallowed easily and moved along.

6Choose the appropriate word from the brackets — (circulation, trachea, diaphragm).

(a) Respiration takes place because of its up and down movement. — diaphragm

(b) The process of keeping the blood flowing continuously throughout the body. — circulation

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