Why Do We Need Air?
Nobody has to teach a child how to breath. We must breathe to live. In fact, all living plants and animals breathe for keeping alive. All living organism require oxygen which is present in the air which we inhale.
The cycle of inhaling and exhaling, or inspiration and expiration, is called breathing or respiration. Inhaling means taking the air inside our body through the nose or mouth or both. Exhaling means sending out air through the same channels. But when the fresh air from outside reaches inside us. our body uses some of its oxygen to keep us healthy and alive. The air that the body sends out has about one-fifth of the oxygen exchanged for the same amount of carbon dioxide.
The carbon dioxide that we exhale is not useful to human body system, but plants make use of this for their living and give out oxygen which is so important for us.
The oxygen that we inhale, reaches our lungs, and is then carried to the tissues of the body with the help of the red cells of the blood. In the tissues this oxygen helps the food that we eat change into usable form and gives us energy and keeps the body cells alive. The waste products, including carbon dioxide and water return to the lungs for exhaling.