Arteries are the blood vessels that carry oxygen-rich blood away from the heart. Veins return the blood to the heart. Diseases of arteries can disrupt the delivery of blood to the organs and slowly or quickly cause problems. There are certain risk factors for some types of artery diseases and high cholesterol is one such risk factor.
Types of Lipids
Cholesterol is a type of lipid. Lipids are fat-like molecules. Triglycerides, or fats, and fatty acids are types of lipids. In the body, cholesterol and other lipids are bound to proteins. These lipid-protein complexes are called lipoproteins. They are assorted by density and include chylomicrons, very low density lipoprotein, or VLDL, low density lipoprotein, or LDL, intermediate density lipoprotein, or IDL, high density lipoprotein, or HDL, and a few others. LDL is known as the "bad" cholesterol. It has the highest concentration of cholesterol and takes cholesterol and fats from the liver into the tissues. HDL is good cholesterol. It takes cholesterol from the tissues to the liver for processing.
Hardening of the Arteries
Processes that harden arteries result in disturbances in blood supply and strain the heart. Arteriosclerosis is the term for hardened arteries. There are different sub-types of arteriosclerosis. The one most associated with cholesterol is atherosclerosis in which atheroma, or plaques, build up in the artery walls.
Atherosclerosis
The liver is able to synthesize enough cholesterol for the needs of the body from the diet. Excess cholesterol and other lipids stick to the blood vessel walls, clogging the arteries with plaque. Atherosclerosis starts with cholesterol being deposited on the blood vessel walls. Immune cells lodge into the lipid deposits and release chemicals that damage tissues, attract more immune cells and promote the thickening of the artery. Hard calcium deposits and connective tissue also develop in the plaque. This causes the arteries to narrow, restricting blood flow. In addition, the plaques can break off, or rupture, causing a complete occlusion, or blockage, of the blood vessel.
Diseases and Mechanisms
The result of atherosclerosis is narrowed dysfunctional arteries. In the arms and legs, this may lead to peripheral artery disease. Peripheral artery disease restricts blood flow to the limbs, which can cause pain when walking, nerve damage, increased risks of infection, and even may require amputation. Atherosclerosis in the heart can lead to heart attacks, and if an artery in the brain is occluded, it can cause a stroke. In the intestines, it can cause pain with eating, called intestinal angina, or if an artery is occluded, part of the intestine can die, requiring emergency surgery.
References
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al.; 8th Ed 2009
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al.; 17th Ed 2008
- "Current Medical Diagnosis and Treatment 2011"; Stephen McPhee, Maxine Papadakis, and Michael W. Rabow; 50th Ed 2010
