Breathing is living. But why is it necessary and how is it that the human body can breathe?
First and foremost, one should comprehend that the cells of the human body require an incessant supply of oxygen. It is responsible for the metabolic function; thus without oxygen the body cannot sustain life.
The respiratory system
While the respiratory system is known as the part that allows a person to breathe, it is rarely understood by the average individual how complex it is. It is the respiratory system, along with the circulatory system, that make oxygen available to the body while ridding of the waste produced by metabolism.
Another of its functions is to control the pH (the measure of the hydrogen ion (H-) concentration; normal pH 7.35-7.45) of the blood. The body has upper and lower airways which allow air to enter and exit the body. This series of events results in the exchange of oxygen and carbon dioxide involving the atmosphere and the body cells. Nerve impulses take place which signal the breathing process. What that actually does is to circulate the air through a chain of passages in and out of the lungs every 3 to 5 seconds.
The lungs and the blood exchange gases, which is called external respiration. The gases are then carried through the blood to and from the tissue cells. This exchange (between blood and tissue) is called internal respiration. At this point, the cells are able to use the oxygen for their needs, and this is known as cellular metabolism or cellular respiration.
It does not end there, however. In order for the process to be complete there need to be physical forces that promote breathing. And that is made possible by muscles such as the diaphragm.
Why the body needs to breathe
For the body to be able to move it needs energy. Energy is found in the food consumed. It is oxygen which makes it possible for the cells to capture and utilize that energy. The result of this procedure is not only the attainment of energy but also a waste product – carbon dioxide, which it must dispose of.
Therefore, it is the breathing which makes it possible for a constant supply of oxygen to enter and the waste matter to exit.
How the body breathes
Breathing is a very mechanical process that has been ingeniously designed. The lungs are covered by two membranes the visceral pleura (Greek for side), which are the immediate membrane covering the lungs and the parietal pleura (or the outside pleura), which is over the visceral and is attached at its base to the diaphragm (between the two is a space known as the pleural cavity).
When a person inhales, the diaphragm contracts and flattens. As this takes place, the parietal pleura stretch. The air pressure in the pleural cavity lowers as the pleura stretch, causing the lungs to stretch downward as they are sucked outward, much like a vacuum.
As they stretch, air is taken in due to the lower air pressure. This is due to the fact that when there is an area of high pressure it pushes air toward an area of low pressure. Then there is the exchange of gases which takes place in the alveoli. These are tiny air sacs at the tip of the bronchioles (the lungs’ smallest airways). The primary role of the alveoli is the exchange of oxygen and carbon dioxide.
As described above, oxygen is inhaled and carried to the blood, and carbon dioxide is taken from the blood and carried to the air in the lungs, which is exhaled into the atmosphere.
The breathing process is a recurring cycle of inhalation and exhalation. A vital part in this process is the diaphragm which contracts making inhalation possible. As it relaxes, exhalation takes place. The lungs are able to recoil back to their original state, squeezing out the unwanted carbon dioxide while awaiting the process to begin yet again.