Bronchus

The bronchi are part of the respiratory system.

Function of the bronchi

The bronchi are involved in air (inspired or expired) passing between the outside and inside of the lungs. They branch from the trachea into several bronchi and bronchioles (from largest to smallest diameter). The pulmonary alveoli, where gas exchange takes place, are at the very end of them.

Structure of the bronchi

The bronchi are fibrocartilaginous channels lined with muscles and an epithelium that secretes bronchial mucus. They are approximately 1 centimetre in diameter. The branching of the bronchi follows a hierarchy:

• there are two main bronchi which leave the trachea each going to a lung;
• The lobar bronchi go to the pulmonary lobes;
• and the segmental bronchi;
• to the bronchioles.