Breathing mechanism

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Breathing is an automatic act and semivoluntario regulated by a neuronal system complex, whose basic function is the exchange of gases between the atmosphere and the blood. The success of this process ensures, that the levels of oxygen (O2) and carbon dioxide ( CO2) in the tissue remains constant. The breath ensures the exchange and transport of gases through the mechanical ventilation, which is performed by the respiratory system.

Breathing mechanism is implemented in a biphasic cycle: inspiration, the active movement, which allows to attract external air to the lungs and exhalation, which by contrast, is a passive phenomenon, in which meanwhile relaxing the diaphragm, the elasticity of the lungs provokes the expulsion of the with carbon dioxide loaded air and the diaphragm returns to the starting position. Air enters the lungs, when the pressure inside is lower than atmospheric. On the contrary, the air is expelled when the pressure is greater than the atmospheric. The normal respiratory volume per minute is twelve to fifteen times and in every breath we introduce about half a liter of air in the lungs.

In inspiration, the action of the external intercostal muscles exerts a lift and rotate the ribs to increase the diameter of the chest cavity. These changes increase the volume of the chest cavity and the intrathoracic pressure decreases, what results in the entry of air into the lungs. The diaphragm is the main muscle involved in breathing. At the expiration for its part, chest and lung elasticity tend to carry the chest to steady state, the contracted muscles relax during inspiration decreasing the size of the rib cage and increasing intrathoracic pressure. At this point occurs the air exhale and the balance of pressure is reestablished.