5th std EVS chapter 21 busy at work our internal organs l question and answer l explanation in marathi

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Environmental Studies -  5th Standard

21. Busy at Work – Our Internal Organs

Question And Answer

Q1. What’s the solution ?

A person has fainted and a crowd of people has surrounded him.

Ans: When a person faints, he should be immediately given clean and fresh air. Therefore ask the crowd to move away. Then splash cold water on the face of this man. If he is not reviving, take him immediately to the doctor with the help of others.

Q2. Use your brain power !

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

Ans: The upper ends of both the oesophagus and the trachea open in the throat next to each other, there is a flap that covers the trachea. When the food is swallowed, the trachea remains closed. But if we eat in a hurry, the food enters the trachea. This causes choking. But due to coordination of the brain, we immediately start coughing and the food particles are expelled out of the trachea.

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

Ans: There are tiny, fine hair-like outgrowths called cilia inside the nose from where the air passes inside. Larger dust particles get caught in these hairs. The air going inside the trachea thus gets filtered. There is also a layer of a sticky substance called mucous. The dust and smoke particles stick to the mucous. Thus the air that we inhale gets purified before it reaches the lungs.

Q3. Fill in the blanks.

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

(b) The stomach is like a bag .

Q4. Match the following.

Q5. Answer the following questions

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

Ans: Respiratory system, digestive system, circulatory system, nervous system, skeletal system and excretory system are some of the systems that carry out different

functions of the body.

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

Ans: At the time of respiration, the external air reaches up to the alveoli in the lungs. The oxygen in the air enters the blood vessels which surround the alveoli. Through the network of blood vessels oxygen is supplied to the entire body. At the same time, carbon dioxide is brought by the circulating blood into the alveoli. From here carbon dioxide is given out of the body through exhalation. In this way exchange of oxygen and carbon dioxide gases take place in the alveoli of the lungs.

(c) Why do we call saliva a digestive juice ?

Ans: Saliva is the juice secreted by the salivary glands. Saliva helps to make bolus from the food that we eat. Saliva also contains a starch digesting enzyme. This enzyme turns starch into sugar. Therefore saliva is called a digestive juice.

Q6. Choose 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

(c) Air that enters through the nose passes into this tube. - Trachea

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