There are different parts:

• Trachea is a tube that divides into two thinner tubes named bronchial tubes or bronchi.

• Each bronchial tube (bronchus) passes into each lung, and continues to branch within the lung. These branches are called bronchioles and each bronchiole leads to a tiny cluster of air sacs called alveoli, where the exchange of gasses occurs, so that the air and gases breathed in get diffused to the blood..

• Lungs are two bag-shaped and spongy organs inside thoracic cavity. Oxygen is carrying to blood inside it.