The first defense within the nose, mouth, throat, and lungs against infectious microbes is

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Quizplus · Accepted Answer

Immunoglobulin IgA plays a significant role in protecting the nasal, oral, and respiratory systems from infectious agents. It is predominantly found in secretions like mucus, saliva, and tears, where it functions as a barrier agent against pathogens. IgA can also neutralize virus particles and toxins, which helps in preventing infections. CRH, cortisol, and epinephrine are hormones involved in stress responses and not directly related to the immune system's defense mechanisms. The release of antigens is a process that aids in the recognition of foreign particles by the immune system and not a defense mechanism by itself.

The First Defense Within the Nose, Mouth, Throat, and Lungs