4th Class Science Our Body Respiration

     Respiration in Human

Respiration is a process by which body burns organic matter (glucose) in the presence of oxygen to release energy. This energy is needed for work, growth, development and maintenance of the body. The human respiratory system consists of nose, windpipe and lungs. We breathe air through our nose. The air has oxygen in it. This air now moves down from windpipe to the lungs. The lungs are present inside our rib cage. We have a pair of them. It is a soft spongy bag like organ. Each of our lungs has millions of branching air sacs known as bronchioles.

Respiration in Human At the end of each bronchioles there are bunches of air sacs known as alveoli. During the process of respiration, oxygen from the air seeps through the air sacs into the blood and at the same time carbon dioxide seeps back into the air sac and is thrown out when we breathe out.      

    When a person runs or does some hard physical work, what happens to his breathing?

(a) Breathes faster

(b) Breathes slow

(c) Breathes at the normal rate

(d) None of these

(e) All of these

Answer: (a)

     Name the gas that all living things breathe in

(a) Oxygen

(b) Carbon dioxide

(c) Hydrogen

(d) Nitrogen

(e) All of these

Answer: (a)