A person can live for weeks without food and a few days without water but only few minutes without oxygen. Every cell in the body needs a constant supply of oxygen to produce energy to grow, repair or replace itself, and maintain vital functions. The oxygen must be provided to the cells in a way that they can use. It must be brought into the body as air that is cleaned, cooled or heated, humidified and delivered at the right amount.
The respiratory system is the body’s link to this supply of life-giving oxygen. It includes the diaphragm and chest muscle, the nose and mouth, the pharynx and trachea, the bronchial tree, and the lungs. The bloodstream, the heart and the brain are also involved. The bloodstream takes oxygen from the lungs to the rest of the body and returns carbon dioxide to them to removed. The heart creates the force to move the blood at the right speed and pressure throughout the body. The smooth functioning of the entire system is directed by the brain and the autonomic nervous syatem.
A person at rest breathes about 6 liter of air a minute. Heavy exercise can increase the amount to over 75 liters per minute. During 8-hour work day of moderate activity, the amount of air breathed may be as much as 8.5 m3 .The skin, with its surface area of approximately 1,9 m2 is commonly thought to have the greatest exposure to air of any body part. However, in reality the lungs have the greatest exposure, with a surface area exposed to air of 28 m2 at rest and up to 93 m2 during a deep breath.
The respiratory system is susceptible to damage caused by inhaled toxic materials and irritants because the surface area of the lungs exposed to the air is so large and the body’s need for oxygen so great. The ability of the respiratory system to function properly has a great impact on the body. Disease in any one of its parts can lead to disease or damage to other vital organs.