Cholesterol monitor
Cholesterol is a steroid alcohol and is present in animal cells and body fluids. Cholesterol is the metabolic precursor of steroid hormones and bile acids as well as an essential constituent of cell membranes. Cholesterol is ingested in the diet and is synthesized also by the liver and other tissues. Most of the cholesterol in the human body is manufactured in the liver. Some of this cholesterol is turned into bile which is excreted by the liver via the bile ducts into the small intestine. Cholesterol in the bloodstream, known as serum cholesterol, circulates bound to two special proteins, low density lipoprotein (LDL) and high density lipoprotein (HDL). Two other lipoproteins, the chylomicrons and the very low density lipoproteins, are relatively unimportant although both ultimately convert to LDL. LDL is "bad cholesterol" and high levels are associated with atherosclerosis. HDL, on the other hand, is "good cholesterol" and is seen as something of a scavenger to remove errant cholesterol from the system. Because most cholesterol is bound to LDL, total serum cholesterol parallels the LDL levels in the bloodstream. Dietary cholesterol is transported from the intestine to the liver by large lipoprotein molecules in the blood. The liver secretes Very Low Density Lipoprotein (VLDL) which transports cholesterol and cholesterol ester and various other compounds into the bloodstream. VLDL is partially converted in adipose tissue to Low Density Lipoprotein (LDL). LDL transports both free and esterified cholesterol to body tissues. High Density Lipoprotein (HDL) transports cholesterol to the liver to be broken down and excreted. Cholesterol esters are a major component of atherosclerotic lesions and the major storage form of cholesterol in arterial wall cells. Formation of cholesterol esters is also a key step in the intestinal absorption of dietary cholesterol. Chylomicrons, VLDLs, IDLs, and LDLs transport exogenous and endogenous cholesterol and triacylglycerols to peripheral sites, where the lipids play a role in various metabolic pathways and serve as a major constituent of cell membranes. Cholesterol levels are widely regarded as a reliable indicator of prospective health problems attributable, for example, to coronary disease. It is known that high levels of cholesterol of the blood lead to a build up of plaque on the wall of arteries and veins thereby restricting blood flow and causing a dangerous health situation. The condition of an excessive amount of plaque build up in the arteries and veins is known as atherosclerosis. Build up of excessive amount of plaque in the arteries is called artereosclerosis. Atherosclerosis is the thickening and loss of elasticity in the inner walls of arteries, accompanied by the formation of small fatty modules on the artery walls and degeneration of the affected area. Atherosclerosis is a leading cause of death, myocardial infarctions, stroke, peripheral vascular disease and cardiovascular disease. Atherosclerosis presented in the form of coronary heart disease and cerebrovascular diseases are major causes of morbidity and mortality in many industrial countries. Elevated plasma levels of low density lipoprotein-cholesterol complex (LDL-C) correlate with an increased risk for the development of atherosclerosis. Atherosclerosis is characterized by the deposition of fatty substances, primarily cholesterol, and subsequent fibrosis in the inner layer (intima) of an artery, resulting in plaque deposition on the inner surface of the arterial wall and degenerative changes within it. In atherosclerosis, cholesterol (unesterified, esterified, and oxidized forms) and other lipids accumulate in cells and in extracellular areas of the arterial wall and elsewhere. These lipids have potentially harmful biologic effects, for example, by changing cellular functions, including gene expression, and by narrowing the vessel lumen, obstructing the flow of blood. Risk factors for atherosclerotic coronary heart disease include hypertension, diabetes mellitus, family history, male sex, cigarette smoking and serum cholesterol. A total cholesterol level in excess of 225-250 mg/dl is associated with significant elevation of risk.
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