Which of the following conditions alter normal mucociliary clearance? 1. Bronchospasm 2. Cystic fibrosis (CF) 3. Ciliary dyskinesia 4. Asthma

a. 1, 2, and 4 only
b. 1 and 2 only
c. 1 and 4 only
d. 2 and 3 only

ANS: D
Diseases that alter normal mucociliary clearance can also cause secretion retention. CF is a com-mon disorder in this category. In CF, the solute concentration of the mucus is altered because of abnormal sodium and chloride transport. This increases mucus viscosity and impairs its movement up the respiratory tract. Although less common, there are several conditions in which the respira-tory tract cilia do not function properly. These ciliary dyskinetic syndromes also can contribute to ineffective airway clearance.