The nasal hairs, convoluted passages, and mucous lining of the nasal turbinates:
a. nonspecifically protect the respiratory tract from infection.
b. promote colonization of normal bacterial flora.
c. can aid adherence by potentially harmful bacteria.
d. reduce colonization of normal bacterial flora.
A
The human host has several mechanisms that nonspecifically protect the respiratory tract from infection: the nasal hairs, convoluted passages, and mucous lining of the nasal turbinates; secre-tory immunoglobulin A (IgA) and nonspecific antibacterial substances (lysozyme) in respiratory secretions; the cilia and mucous lining of the trachea; and reflexes such as coughing, sneezing, and swallowing. These mechanisms prevent foreign objects or organisms from entering the bronchi and gaining access to the lungs, which remain sterile in the healthy host.
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