Which part of the lung is primarily affected by pulmonary fibrosis?

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

Answer: (A)

Pulmonary fibrosis primarily affects the alveoli, which are the tiny air sacs in the lungs where gas exchange occurs. In this condition, the lung tissue becomes thickened and scarred, leading to a reduction in the elasticity of the alveoli. This scarring interferes with the ability of the alveoli to expand and contract properly during breathing, impeding the exchange of oxygen and carbon dioxide. As a result, patients may experience symptoms such as shortness of breath and a persistent dry cough due to the diminished efficiency of gas exchange.

The other structures mentioned, such as the bronchioles, trachea, and pleura, are not primarily affected in pulmonary fibrosis. Bronchioles are small airways leading to the alveoli and may not directly suffer from the scarring associated with this condition. The trachea is the main airway that conducts air from the throat to the lungs and is typically not impacted by the fibrotic changes associated with pulmonary fibrosis. The pleura are the membranes surrounding the lungs, which can be involved in other conditions but are not the focal point in pulmonary fibrosis itself. Thus, the alveoli are the primary site affected in this disease, leading to the characteristic pulmonary symptoms.