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PCAT Biological Processes – Respiratory Defenses

All of the following protect the respiratory system from inhaled pathogens and foreign objects EXCEPT:

A. mucus produced by goblet cells.
B. cilia lining the epithelium of the trachea.
C. surfactant that coats the tracheal surface.
D. the epiglottis.

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C is correct. Surfactant is found in the alveoli and serves to reduce surface tension; it does not coat the tracheal surface to protect against pathogens. Goblet cells do produce mucus, which traps small particulate matter, and the tracheal epithelium contains cilia that push mucus and particles toward the back of the throat. Finally, the epiglottis closes while eating to protect the lungs from swallowed objects, in particular food.

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