The lower respiratory tract is protected by all of the following EXCEPT
A) IgA antibodies.
B) mucous secretions.
C) competition with the normal flora of the lungs.
D) alveolar macrophages.
E) the ciliary escalator.

Question

Quizplus · Accepted Answer

The lower respiratory tract is typically sterile and does not have a normal flora, so competition with normal flora is not a protective mechanism for this part of the respiratory system.

The Lower Respiratory Tract Is Protected by All of the Following