AEMCA Practice Exam

Irritant receptors in the lungs play a crucial role in protecting the respiratory system primarily by inducing bronchial constriction. When these receptors detect harmful substances or irritants in the air, such as smoke or allergens, they trigger a reflex response that leads to the constriction of the bronchial smooth muscles. This action helps to limit airflow and reduce the entry of these potentially harmful particles into the lower respiratory tract. By narrowing the airways, the body effectively minimizes exposure to irritants, assisting in the overall protective mechanism of the respiratory system.

The other options do not directly relate to how irritant receptors function. While enhancing mucus production could be a protective mechanism against irritants, it is not the primary response facilitated by irritant receptors. Expanding airways and promoting deeper breathing are more related to the relaxation of bronchial muscles, which would be counterproductive in the presence of irritants.