Breathing is a mechanical process consisting of two phases:
Inspiration or inhalation or intake of fresh air into the lungs.
Expiration or respiration or out of impulse and air consumed out of the lungs.
Breathing is associated with the existence of life itself. The lung itself cannot pull air or push it out. Therefore, human breath with the suction pump mechanism. The chest wall and diaphragm act as large pumps in moving air in and out of the lungs. In humans when breathing normally, 500ml of air moves in and out of the lungs every time you breathe. The mechanism of breathing: We know that breathing consists of two phases, namely breathing in or inspiring and breathing out or expiring. Many factors are involved in the mechanism of breathing, eg
Contractions and relaxation of intercostal muscles between the ribs bring changes in the position of the ribs and sternum. When these muscles contract, the ribs lift and move up and forward and when these muscles relax, the ribs settle and move in and back. The breastbone also moves in and back.
Contraction and relaxation of the diaphragm muscles bring changes to their shape. When these muscles contract, the diaphragm becomes like a dome or convex
The elasticity and elasticity of the lungs causes expansion and contraction. They expand when breathing and contract during breathing.
Breathing or inspiration: In humans, inspiration is an active process. During inspiration, the intercostal muscles between the ribs contract and pull the rib cage forward and outward, pushing the sternum further from the spinal column. With the contraction of the intercostal muscles and diaphragm, the size of the thorax as a whole increases and the inner pleural cavity enlarges. Because the pleural cavity is closed therefore their enlargement tends to create a partial vacuum in it. Lungs are elastic and communicate with the atmosphere through the airways (trachea, bronchi). As soon as the pressure around the lungs is lowered, air flows in through the trachea and bronchi. In this way the lungs expand to fill the pleural cavity and the pressure on the inner and outer thorax is equalized. Thus the mechanism of human breathing is the mechanism of the suction pump. The lungs are made to expand and contract with the movement of the ribs and diaphragm.
Breathing or expiration: Expiration in humans is usually a passive process. But in heavy muscle training, expiration also becomes active. During expiration, the intercostal muscles of the ribs relax, the ribs move downward and inward. Thus the size of the chest cavity is reduced from side to side. The breastbone reaches its original position, reducing the size of the chest cavity from front to back. At the same time the muscles of the diaphragm relax so that the diaphragm takes a dome-shaped position. So by relaxing the muscles of the diaphragm and intercostal muscles, the overall size of the chest cavity decreases. Reducing the size of the thorax puts pressure on the lungs. The lungs themselves are very elastic and tend to return to their original size. When the lungs are pressed, dirty air in them is expelled or expiration occurs.