Particles smaller than 2 micrometers can lead to what consequence if not effectively removed?

• A. Trapped in the nasal cavity
• B. Engulfed by alveolar macrophages only
• C. Injury to the epithelium and potential disease
• D. Immediately expelled through coughing

Answer: (C)

Particles smaller than 2 micrometers can penetrate deep into the respiratory system, reaching the alveoli where gas exchange occurs. When these fine particles are not effectively removed, they can evade the body's natural defense mechanisms, resulting in injury to the epithelium of the lungs. This injury can manifest as inflammation, impaired gas exchange, and even stimulate the development of respiratory diseases such as chronic obstructive pulmonary disease (COPD), asthma, and lung fibrosis.

The presence of these particles can lead to an immune response, resulting in the release of inflammatory mediators that further exacerbate lung tissue damage and contribute to disease progression.

In contrast, larger particles tend to get trapped in the upper respiratory tract, such as the nasal cavity, and might be expelled through coughing or other reflex actions. Alveolar macrophages play a role in clearing inhaled particles, but they are not the only mechanism involved, particularly when dealing with particles that can cause significant damage. Thus, the consequences of smaller particles not being effectively cleared can escalate into serious health issues within the pulmonary system.