Which mechanism expels particles that are 2 to 10 micrometers in size?

• A. Cough reflex
• B. Sneeze reflex
• C. Mucociliary escalator
• D. Alveolar macrophage activity

Answer: (C)

The mechanism that effectively expels particles measuring between 2 to 10 micrometers in size is the mucociliary escalator. This defense mechanism plays a critical role in the respiratory system by utilizing cilia, which are tiny hair-like structures lining the respiratory tract, to move mucus that traps inhaled particles, such as dust, pollen, and pathogens, upwards towards the throat.

The mucus is produced by goblet cells and other mucous-secreting glands and forms a protective barrier within the airways. Both the cilia's coordinated movement and the sticky nature of mucus ensure that these trapped particles are transported out of the lungs and into the pharynx, where they can be swallowed or expectorated.

Particles within the size range of 2 to 10 micrometers are too large to effectively reach the alveoli, where gas exchange occurs, and thus can be removed by this mechanism, safeguarding the lungs from potential irritants and infections.

While the cough and sneeze reflexes are also important particulate expulsion mechanisms, they primarily serve to expel larger particles. Alveolar macrophages play a crucial role in the immune defense within the alveolar space, targeting pathogens and smaller particles, but their activity is not