Your bronchial tubes are the tubes where air passes through your lungs. When you breathe air in, it passes from your nose or mouth, through the larynx, and into the trachea or wind pipe.
From your trachea, air splits off into your right and left main bronchial tubes, or right and left main bronchus.
As your bronchial tubes continue to branch off and get smaller and smaller, they are referred to as bronchi and then bronchioles. Your airways terminate at the alveoli, where exchange of carbon dioxide and oxygen takes place.
Asthma usually does not permanently damage the structure of the bronchial tubes, but other diseases can, such as: