airway

An airway is any of the tubes that air travels through on its way in and out of the lungs — the plumbing of breathing. Like a road network feeding a city, the airways carry the traffic of air toward the places where gas is actually exchanged, and out again.

The airways begin wide and few — the trachea and main bronchi — and branch some twenty-three times into ever narrower, more numerous tubes, ending at the alveoli. Most of this network simply conducts air; only the last few generations of branches take part in gas exchange. The walls contain muscle, cartilage and a moist, ciliated lining that cleans the air and can widen or narrow the passage.

In clinical speech the word has two flavours. It can mean the patient's natural air passages and their diseases, such as asthma narrowing the airways. It can also mean a managed or artificial airway — the open, secured passage an emergency team works to establish, sometimes with a breathing tube, when someone cannot breathe on their own.