Bronchial/Tracheal cells are from the lining of the bronchi/trachea, the network of tubes used to convey air to the lungs. Bronchial/Tracheal cells are responsible for producing lubricating mucus to keep the airways functional and they are a type of epithelial cell, a term used generally to refer to cells lining the inside or outside of the body. These cells generate mucus and a number of other compounds, which play an important role in respiration.