Question

What is mechanism of breathing?

Answer 1

Breathing is a mechanical process characterized by two phases:
1. Inspiration or inhalation which is the intake of fresh air in to the lungs.
2. Expiration or exhalation which is the out push of the consumed air out of the lungs.
The action of breathing in and out is caused because of pressure changes within the thorax, in comparison with the outside. When we inhale, the intercostal muscles and diaphragm contract resulting in the expansion of the chest cavity. The diaphragm flattens and moves downwards and the intercostal muscles move the rib cage upwards and out. This increase in size decreases the internal air pressure and so air from the outside which is now at a higher pressure than that inside the thorax, rushes into the lungs. On exhalation, the diaphragm and intercostal muscles relax, returning to their resting positions which reduces the size of the thoracic cavity, consequently increasing the pressure and forcing the consumed air out of the lungs.