02-05-2009, 06:51 AM
Cystic fibrosis affects the respiratory system by causing an excess production of viscous mucus by the bronchial glands, followed by mucous plugging and obstruction of the respiratory airway, particularly a small airway, such as that in a child. The alveolar duct is a part of this respiratory unit. The other structures are not affected because they are large airways and are not usually obstructed and thus do not help in making the diagnosis.