Basic and Clinical Sciences (BCSE) Practice Exam

The pathology involved in pulmonary arterial hypertension (PAH) is best characterized by vasoconstriction and cell proliferation. In PAH, there is an abnormal increase in blood pressure in the pulmonary arteries, which is often a result of resistance to blood flow. This resistance can stem from a variety of mechanisms, including the narrowing of the pulmonary arteries due to excessive smooth muscle contraction (vasoconstriction) and the proliferation of endothelial and smooth muscle cells in the vascular walls. These changes lead to thickening of the vessel walls, which further contributes to increased vascular resistance.

The increased pressure in the pulmonary arteries causes strain on the right side of the heart, which can eventually lead to right heart failure if left untreated. The pathophysiological mechanisms of vasoconstriction and cellular proliferation are critical in understanding both the progression and management of PAH, making this choice the most accurate description of the condition's underlying pathology.

By contrast, the other options describe processes that are not characteristic of the primary pathology in PAH. Alveolar collapse and hyperinflation, for instance, are associated with obstructive lung diseases rather than the vascular changes seen in PAH. Similarly, bronchial obstruction and atelectasis involve airway issues rather than pulmonary arterial alterations