THE breathing it is an essential process for human beings, since it is through it that the oxygen that will be used by cells for energy production is made available. In addition, the respiratory system is responsible for removing the carbon dioxide resulting from cell metabolism.
For the breathing process to occur, a joint action of the intercostal muscles and the diaphragm is necessary, which allow the entry and exit of air. The act of breathing can be divided into two basic movements: inhalation and exhalation.
Inspiration it is the set of movements that allow air to enter the lungs. In this process, the diaphragm contracts, causing it to lower. The intercostal muscles also contract causing the ribs to lift. This causes the chest to increase in size and the pressure inside the lungs to become less than the pressure outside. With the reduction in intrapulmonary pressure, the air ends up entering the airways and reaching the alveoli for gas exchange to occur.
THE expiration it consists of the set of movements that result in the removal of air from the interior of the airways. In this case, the intercostal muscles and diaphragm relax. Unlike what happens during inspiration, there is a reduction in the volume of the rib cage, which returns to your rest size, and a retraction of the lungs, which causes the internal pressure to be greater than the external. Increased intrapulmonary pressure causes air to be thrown out of our body.
We can summarize these two processes as follows:
Observe what happens in our body at the time of inhalation and exhalation
By Ma. Vanessa dos Santos
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/biologia/o-que-e-inspiracao-expiracao.htm