The process of breakdown of food in the cell with the release of energy is called cellular respiration. Cellular respiration takes place in the cells of all organisms. Breathing is a part of respiration.
When breakdown of glucose occurs with the use of oxygen it is called aerobic respiration and Food can also be broken down, without using oxygen is known as anaerobic respiration.
Glucose in the presence of oxygen/heat → carbon dioxide + water + energy
There are some organisms such as yeast that can survive in the absence o-f air is called anaerobes.
Glucose in the absence of oxygen/heat → alcohol + carbon dioxide + energy
Breathing means taking in air rich in oxygen and giving out air rich in carbon dioxide with the help of respiratory organs. The taking in of air rich in oxygen into the body is called inhalation and giving out of air rich in carbon dioxide is known as exhalation.
The number of times a person breathes in a minute is termed as the breathing rate. During breathing inhalation and exhalation take place alternately. A breath means one inhalation plus one exhalation.
Normally we take in air through our nostrils. When we inhale air, it passes through our nostrils into the nasal cavity. From the nasal cavity, the air reaches our lungs through the windpipe. Lungs are present in the chest cavity.
A large, muscular sheet called diaphragm forms the floor of the chest cavity Breathing involves the movement of the diaphragm and the rib cage.
During inhalation, ribs move up and outwards and diaphragm moves down. This movement increases space in our chest cavity and air rushes into the lungs. The lungs get filled with air.
While breathe out, we exhale only carbon dioxide and a mixture of gases along with
it. During the breathing more oxygen can be supplied to the body cells resulting in release of more energy.
The percentage of oxygen and carbon dioxide in inhaled and exhaled air.
Animals such as elephants, lions, cows, goats, frogs, lizards, snakes, birds, have lungs in their chest cavities like the human beings.
A cockroach has small openings on the sides of its body. Other insects also have similar openings. These openings are called spiracles.
Insects have a network of air tubes called tracheae for gas exchange.
The earthworms breathe through their skins. The skin of an earthworm feels moist and slimy on touching. Gases can easily pass through them.
There are many organisms which live in water. Gills are projections of the skin. You may wonder how gills help in breathing. Gills are well supplied with blood vessels.
Like other living organisms, plants also respire for their survival They also take in oxygen from the air and give out carbon dioxide. In the cells oxygen is used to break down glucose into carbon dioxide and water as in other organisms.
