The bronchi (singular: bronchus) and the lungs make up the lower respiratory tract .

There are two main bronchi which conduct air from the trachea into the lungs - one to the left and the other to the right.

The lungs are the main organs of the respiratory system. They are cone-shaped, spongy, structures that fill the chest cavity, one lying on each side. The bases of the lungs rest on the diaphragm.