Key structures of the respiratory system 2 Functional Divisions The conducting portion • Conducts air, and comprises: the nose, nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles. • No gas exchange occurs in these structures. • Terminal bronchiole terminates the conducting portion of the respiratory tract. The respiratory portion • Site of gas exchange, and comprises: the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli. Nose • Opens the respiratory system to…