Atherosclerosis is characterized by the buildup of arterial plaque. When plaque first begins to form, on which part of the blood vessel do the monocytes bind after taking in cholesterol-rich lipoproteins?

on the smooth endothelial lining

Explanation:

The endothelial lining is the innermost layer of all cardiovascular system. it serve as the separating barrier between the circulating blood and the inner lining of vascular system. These cells formed one cell layer thick of capillaries for exchange of nutrients and gases between the blood and the needed cells and tissues, also as lining of the innermost layers of the heart for diffusion of nutrients to the cardiac cells.

The process of deposit of plaques on the walls of the arteries, which leads to narrowing and hardened of the arteries is called Atherosclerosis.

Monocytes and microphages are attracted to the blood vessels by the circulating cytokines and chemokines from plaque activation. The monocytes and macrophages bind with blood vessels, and squeeze their way through to bind with the endothelial lining on the arterial wall to feed or scavenge on the oxidized low density lipoprotein in the plaque.

This is followed by corresponding efflux or release of cholesterol from the macrophages into the endothelial lining increasing the mass of the plaque, aggravating atherosclerosis.

the endothelial lining