AEMCA Practice Exam

What triggers bronchial constriction in irritant receptors located within the lungs?

1. Excessive humidity

2. Nitrogenous substances like smoke

3. Inflammatory responses

4. High levels of oxygen

The correct answer is: Nitrogenous substances like smoke

Bronchial constriction in irritant receptors within the lungs is primarily triggered by nitrogenous substances, such as smoke. These irritants directly stimulate the sensory receptors located in the airway epithelium, leading to a reflex response which causes contraction of the bronchial smooth muscle. The body reacts to these harmful substances through this mechanical response to help reduce airflow and limit further inhalation of irritants, ultimately working as a protective mechanism for the respiratory system. Other factors, such as excessive humidity, high levels of oxygen, and inflammatory responses, may have effects on the respiratory system but do not directly trigger the irritating receptors in the same manner as nitrogenous substances do. They might contribute to respiratory discomfort or complications, but the immediate bronchial constriction response is specifically linked to irritants like smoke, leading to the selection of that answer as the most accurate choice for this question.