Final answer:
The cough reflex is activated when the trachea is irritated by food or other foreign objects entering it, causing an individual to cough and force the object out.
Step-by-step explanation:
The cough reflex is triggered by irritation of an important medical landmark known as the trachea. When food or other foreign objects inadvertently enter the trachea instead of the esophagus, the body's reflex is to cough. This reflex action usually forces the object up and out of the trachea, back into the pharynx.
The cough reflex is closely tied to the process of swallowing, where the soft palate and uvula rise to close off the entrance to the nasopharynx, and the epiglottis folds inferiorly to prevent food from entering the trachea. When food "goes down the wrong way," entering the trachea instead of the esophagus, the cough reflex is activated to correct the mistake.