Inspiration and Expiration: the air in and out of our lungs
Human breathing occurs through the air in and out of the lungs. This process depends on the variation of the pressure in the pulmonary alveoli in relation to the atmospheric air pressure.
The process of inspiration (inhalation of air)
- Contraction of the diaphragm muscle occurs and it lowers and contracts. At the same time, rib elevation occurs. In this way there is the expansion of the ribcage.
- Then, with the increase of space around, the distension of the lungs occurs.
- As a result, the lungs increase in volume, causing the internal pressure to drop. Thus, there is a favor for inhalation (inlet) of air, because the external pressure of atmospheric air is higher.
The Exhalation Process (Air Exhalation)
- First, relaxation of the diaphragm occurs. The ribs lower. Thus, the size of the rib cage occurs.
- Then the lungs contract as they get squeezed.
- The pressure inside the lungs increases with decreasing volume relative to atmospheric air pressure. Thus air returns through the airways to be exhaled.
Did you know?
- The air is filtered, heated and moistened as it passes through the nose.
- In some situations, changes in breathing movements may occur. These occur in sneezing, coughing, sobbing, yawning, laughing and also crying.
- The air we breathe is rich in oxygen. What we exhale is rich in carbon dioxide, although it also has a good amount of oxygen.
When we inhale, about 12 milliliters of air enters our lungs.