Process of Respiration

How do we breathe?

            Breathing is essential for all living beings. It is an involuntary reaction that takes place continuously. Men, animals, birds, insects and plants- all need oxygen, which they get form the air through respiration. However, different creatures breathe in different ways. Some breathe through lungs, some others breathe through their skin. The earthworm is one animal that breathes through its skin. Do you known how man breathes and what happens in the body during the process of respiration?

When diaphragm pulls down, it gives lungs more space to suck sufficient air, when it relaxes, it forces some of the air out of lungs.

            We, human beings, inhale air through the nose or mouth. The nose and mouth are jointed in the back of the mouth in an area called pharynx. The air inhaled goes to the lungs through the windpipe. There are two lungs in our body- one on each side of our chest. They are made up of tissues shaped like soft bags. Each lung has millions of air sacs, which get filled and enlarged when air is inhaled. When it is exhaled, they contract.

            The energy releasing process, which utilize the oxygen and produces carbon dioxide, is termed as tissue respiration or external respiration. In man, external respiration is the process where by air is breathed from the environment into the lungs to provide internal respiration.

            The oxygen, which is inhaled, is circulated throughout the body by the blood. It oxidizes the food materials. During the process of oxidation, carbon dioxide, water and other substances are produced. The same carbon dioxide is expelled when we breathe out. When we do some physical work or exercise, we need more energy. For the production of more energy, we need more oxygen. That is hwy the rate of breathing becomes fast when we do any hard work or physical exercise.

            Normally, a newly born child breathes 60 items per minute. A 15 years old child breathes 20 times a minute and an adult 16 to 18 times. The rate of breathing is faster in adults than in old people. The respiratory center in the brain controls the process of breathing. This center is sensitive to the amount of carbon dioxide in the blood. If there is an increase in carbon dioxide such as during exercise, this center sends signals to control breathing. As a result, the person breathes faster.

How do Fish Breathe inside Water?

            What would happen of one of us were to drown in water? We would die because of suffocation as our lungs would get filled with water. But the fish can easily survive in water. It does not live outside water for long. Have we wondered how a fish can breathe in the water while human beings cannot?

Fishes breath through gills

            Except the lungfish, all other fishes breathe by means of a special structure called gills. They do not have lungs like human beings nor do they breathe through their noses. Their process of respiration is completely different from ours. They take water in their mouths for the purpose of respiration. This water flows over the gills and comes out through the openings behind the cover of gills. The cells of the gills absorb the oxygen in water.

            Since the surface area of the gills is quite large, the amount of oxygen absorbed is also considerable. The oxygen gets mixed in the blood and is circulated throughout the whole body. That is how it purifies the blood. The carbon dioxide produced in the body is brought to the gills by the circulating blood where it gets dissolved in water and passes out of the body. In this way, the cycle of respiration in the fishes continues.

            If the water is dirty, the fishes sometimes come up to the surface of water and take air in for breathing. However, they do not use gills for this purpose, the fish is a cold blooded creature. It is also sensitive to touch, taste, smell, etc. it has different organs for these functions. Scientists have already studied more than 20,000 different species of fishes.