In the Small Airways of the Lung, a Thin Layer

question 78

Multiple Choice

In the small airways of the lung, a thin layer of liquid is needed between the epithelial cells and the mucus layer in order for cilia to beat and move the mucus and trapped particles out of the lung. One hypothesis is that the volume of this airway surface liquid is regulated osmotically by transport of sodium and chloride ions across the epithelial cell membrane. How would the lack of a functional chloride channel in cystic fibrosis patients affect sodium ion transport and the volume of the airway surface liquid?

• A) Sodium ion transport will increase; higher osmotic potential will increase airway surface liquid volume.
• B) Sodium ion transport will increase; higher osmotic potential will decrease airway surface liquid volume.
• C) Sodium ion transport will decrease; lower osmotic potential will decrease airway surface liquid volume.
• D) Sodium ion transport will decrease; lower osmotic potential will increase the airway surface liquid volume.
• E) Sodium ion transport will be unaffected; lack of chloride transport still reduces osmotic potential and decreases the airway surface liquid volume.

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