Bronchiolitis is defined as inflammation of which part of the airway after a viral infection?

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

Answer: (B)

Bronchiolitis is inflammation of the small airways, the bronchioles, after a viral infection. The bronchioles are the narrow passages that carry air from the larger airways to the alveoli. When they become inflamed, the lining swells and mucus is produced, narrowing the lumen. Because these small passages are easily obstructed and lack rigid cartilage, this edema and mucus plugging markedly limit airflow, especially during expiration, leading to rapid breathing and often a wheeze.

Other parts of the airway aren’t the primary site here. The trachea is the large windpipe, so inflammation there would point to tracheitis or a croup-like illness involving the upper airway. The alveoli are the air sacs where gas exchange occurs; inflammation there would indicate pneumonia. The larynx is involved in conditions like laryngitis or croup, which have different symptom patterns such as a hoarse voice or a barking cough. Thus, the hallmark of bronchiolitis is inflammation of the bronchioles.