respiratory tract

In animals, the air passageways that lead from the nose and mouth to the lungs, including the air sacs of the lungs. A specialized epithelial tissue lines much of these air passages. This is cilated epithelium and contains cells with beating hairs called cilia that sweep mucus and trapped particles away from the air sacs in the lungs. Smoking damages this epithelium.

Care should be taken with the term ‘respiratory tract’, because it could be confusing. The word respiration is now linked to processes that occur inside cells and is no longer used to relate to air movements in the air passageways. The term ‘air passageway’ is probably a less confusing term. Air movements in the air passageways are called ventilation (breathing).