Nope, cholesterol does indeed get used to repair cell damage. In fact, over-consumption of vegetable oils, which are unsaturated and have different physical properties compared to saturated fats, causes cholesterol to be used as a structural support:
http://www.nature.com/horizon/livingfro ... d/fat.htmlOther cells use lipids to stiffen their membrane. The myelin sheath that surrounds nerve cells needs to insulate the nerve axon for efficient impulse transmission. These cells' fatty acids have long chains that bond to each other, creating a tough coat. Another way to make the membrane more rigid, and less permeable, is to increase its cholesterol content. Our cell membranes are full of cholesterol — around one molecule for every phospholipid molecule. Cholesterol is smaller than phospholipids, and its structure contains carbon rings that form rigid plates; it slots in the gaps between the larger phospholipid molecules, so restricting their movement and stiffening the membrane.
Here is a nice video explaining the role of cholesterol in compensating for structural deficiencies introduced by unsaturated fats in the cell wall (around the 5 minute mark):
http://www.youtube.com/watch?v=YezCM0pgN5gAs for what arterial plaques are composed of, it ain't so simple. Calcification is the main problem with plaques. They can be dissolved before they calcify but not after. Also, conglomerated fatty-acids in the plaques are 75% unsaturated fats. In addition to oxidized and non-oxidized cholesterol, triglycerides contribute to plaque growth as well. The bottom line is that consuming vegetable oils and sugar contributes to plaque growth just like cholesterol. (The triglycerides are formed from glucose and you can have high triglyceride levels even if you hypothetically consumed no fat.)
For more context, the body uses ingested lipids in cells without rebuilding them. So consuming unsaturated fats has a direct bearing on the composition of the cell walls.
