Which statement accurately describes the pathogenesis of atherosclerosis?

• A. Atherosclerosis affects the small arteries and arterioles.
• B. Atherosclerosis affects the large arteries and arterioles.
• C. Atherosclerosis affects the veins and venules.
• D. Atherosclerosis affects the capillaries only.

Answer: (A)

Atherosclerosis starts with injury to the endothelium of large and medium arteries, setting off an inflammatory process that drives plaque development. Endothelial dysfunction allows LDL to penetrate the intima and become oxidized; those oxidized lipoproteins attract monocytes, which migrate into the wall and become macrophages that ingest the lipids and turn into foam cells, forming the fatty streak—the earliest lesion. Smooth muscle cells then migrate from the media into the intima and proliferate, laying down extracellular matrix to create a fibrous plaque that narrows the vessel lumen. As plaques grow and become unstable, rupture or erosion can expose thrombogenic material to blood, triggering platelet activation and thrombus formation that can acutely occlude the artery, leading to events like myocardial infarction or stroke. This disease classically involves large to medium arteries such as the aorta, coronary, carotid, and peripheral arteries. Involvement of small arteries, arterioles, veins, or capillaries points to other microvascular or systemic processes, not classic atherosclerosis.