Bronchiolitis affects which part of the airway?

• A. Larynx
• B. Bronchioles
• C. Alveoli
• D. Trachea

Answer: (B)

Bronchiolitis affects the bronchioles, the tiny airways just beyond the larger bronchi. In this illness, a viral infection causes inflammation and swelling of the bronchiolar walls with mucus production, narrowing the small passages through which air moves. That small-airway obstruction leads to wheezing, rapid breathing, and work of breathing, especially in infants whose bronchioles are already narrow. The larynx and trachea are part of the upper airway and tend to produce symptoms like a barking cough or stridor when inflamed, which is not the typical pattern of bronchiolitis. The alveoli are the air-exchange units, and infections there produce different signs, such as crackles from pneumonia. Focusing on the site, the bronchioles are the primary structure affected in bronchiolitis.