Particles larger than 10 micrometers are primarily trapped by which anatomical structure?

• A. Nasal hairs and turbinates
• B. Bronchioles
• C. Alveolar sacs
• D. Larynx

Answer: (A)

Particles larger than 10 micrometers are primarily trapped by nasal hairs and turbinates because these structures serve as the first line of defense in the respiratory system. The nasal hairs, or vibrissae, filter out larger particles such as dust, pollen, and other environmental pollutants as air is inhaled through the nasal passages. The turbinates, or nasal conchae, are bony structures that help to humidify and warm the air while also increasing the surface area for more effective trapping of larger particles. This mechanism is crucial in preventing larger particles from reaching the lower respiratory tract, where they could cause irritation or infection.

In contrast, bronchioles and alveolar sacs are designed to handle smaller particles; bronchioles can trap smaller particles and alveolar sacs facilitate gas exchange, which involves much finer filtration and is less effective for larger particulate matter. The larynx, while it does serve to protect the airway during swallowing and contains structures for sound production, is not specifically designed for trapping particles before they enter the lower airways. Thus, nasal hairs and turbinates are the anatomical structures responsible for trapping larger inhaled particles effectively.