Fig. 2
From: Cystic fibrosis lung environment and Pseudomonas aeruginosa infection
The different anatomical divisions of human respiratory system relevant to CF lung disease. Environmental factors such as oxygen and nutrient availability vary significantly in different regions of the human respiratory system and influence disease outcomes. a The airway can be divided primarily into the upper and lower respiratory tract. b Lower respiratory tract is further divided into conductive zone and the respiratory zone. The conducting zones consist of trachea, primary and terminal bronchioles. The conducting zones are secretory in function. The respiratory zones perform the function of air exchange and consist of respiratory bronchioles and alveolar sacs