Which statement best describes the fate of large inhaled particles in the respiratory tract?

• A. They are absorbed in the alveoli
• B. They are exhaled unchanged
• C. They are rapidly cleared in the trachea
• D. They are trapped in the nasopharyngeal region

Answer: (D)

Large inhaled particles have enough inertia that they collide with and deposit on the mucous surfaces of the nose and pharynx as air flows in. This filtration happens early in the airway, so these big particles are effectively trapped in the nasopharyngeal region. Once trapped there, they’re moved by mucus and cilia toward the throat and swallowed, rather than being absorbed deeper in the lungs or simply exhaled unchanged. This was the best description because it matches how particle size determines where deposition occurs: large particles get caught up front, in the nasopharyngeal region.