About Atherosclerosis
Athersclerosis
is a vascular disease arising from an abnormal thickening and hardening
of the arteries. It is caused by the deposit of cholesterol and
other fatty substances on the inner lining of blood vessels, especially
those in the the heart. This disorder is characterized by a inconsistant
thickening of the artery from LDL uptake by cells in the artery.
An LDL is essentially a large complex of proteins and lipids (20-25 nm
in diameter) with the following structure:
Figure 1. LDL structure
These accumulations, referred to as "plaques", start from a fatty yellow "streak," to rounded dots or streaks on the artery surface. Fatty streaks are composed of cells which in turn are comprised primarily of cholesterol and lipids (namely triacylglycerides). Click here to see the chemical formula of a triglyceride (triG) in a popup window.
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Figure 2. The structure of cholesterol.
Triacylglycerides, or TriG, are composed of 3 fatty acids esterified to a glycerol backbone. Click Note the acyl groups are the two long chains of carbon and hydrogen angled to the bottom left corner of the image (in gray and white). An example of a fatty acid is arachidonic acid (click here to view in a popup window).
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 Figure 3. A cholesteryl ester, involved in the core composition of an LDL. |
| Name | Apolipoprotein B-100 |
| Number of polypeptide chains | 1 |
| Amino acid length | 4636 |
| MW | 513000 |
After the development of plaques, the next stage in the pathology of atherosclerosis is "raised plaques." The center of these plaques contains lipid. This lipid is surrounded by a rim of foam cells. The lipid is separated from the lumen of the blood vessel by a collagen cap. The presence of the raised plaques in the aorta and coronary arteries eventually lead to the manifestation of ischemic heart disease and cerebrovascular disease. The incidence of athersclerosis has increased dramatically in the last several decades, dut to changes in dietary habits and lifestyle. It has become one of the leading causes of heart disease and stroke related death in Canada. At present, the factors leading to the development of atherosclerosis remain unclear. Below are two pictures of arteries in advanced stages of atherosclerosis. Note that the diameter of the arteries narrows dramatically with the deposition of fat on the walls, resulting in blood flow obstruction.
Figure
4. An artery with atherosclerosis (Reference:
http://www-medlib.med.utah.edu).e
