bronchioles alveoli air sacs

As you know breathing is an involuntary and automatic process, controlled by pns. It extracts oxygen from the air inspired and expel waste gases with the breath.

The air is inhaled through the nose then it heated and moistened and moves on to the pharynx, larynx and continues to penetrate into the trachea. In the middle of the chest, the trachea is divided into two bronchi which are divided again, again and again, bronchus in secondary, tertiary, and, finally, some 250,000 bronchioles.

At the end of the bronchioles are grouped in clusters of alveoli, small air sacs, where the exchange of gases in the blood. The lungs contain about 300 million alveoli, which deployed occupy an area of 70 square meters, about 40 times the size of the skin