cholesterol

(noun)

A sterol lipid synthesized by the liver and transported in the bloodstream to the membranes of all animal cells; it plays a central role in many biochemical processes and, as a lipoprotein that coats the walls of blood vessels, is associated with cardiovascular disease.

Related Terms

Examples of cholesterol in the following topics:

  • Cholesterol Metabolism

    • However, most ingested cholesterol is esterified; esterified cholesterol is poorly absorbed.
    • The body also compensates for any absorption of additional cholesterol by reducing cholesterol synthesis.
    • For these reasons, cholesterol intake in food has little, if any, effect on total body cholesterol content or concentrations of cholesterol in the blood.
    • Cholesterol is recycled.
    • Microscopic appearance of cholesterol crystals in water.

  • Regulation of Blood Cholesterol Levels

    • Cholesterol is transported through the blood by lipoproteins which direct cholesterol to where it is needed.
    • The cholesterol within all the various lipoproteins is identical, although some cholesterol is carried as the "free" alcohol and some is carried as fatty acyl esters referred to as cholesterol esters.
    • LDL molecules, therefore, are the major carriers of cholesterol in the blood, and each one contains approximately 1,500 molecules of cholesterol ester.
    • When the cell has abundant cholesterol, LDL receptor synthesis is blocked so new cholesterol in the form of LDL molecules cannot be taken up.
    • Also, HDL particles are thought to transport cholesterol back to the liver for excretion or to other tissues that use cholesterol to synthesize hormones in a process known as reverse cholesterol transport (RCT).

  • Gallstones

    • To be classified as such, they must be 80% cholesterol by weight.
    • They contain less than 20% of cholesterol.
    • Mixed gallstones typically contain 20%–80% cholesterol.
    • Cholesterol gallstones develop when bile contains too much cholesterol and not enough bile salts.
    • Besides a high concentration of cholesterol, two other factors are important in causing gallstones.

  • Diagnostic Blood Tests

    • Blood tests focusing on cholesterol levels can determine LDL and HDL cholesterol levels, as well as triglyceride levels.
    • Some blood tests, such as those that measure glucose, cholesterol, or for determining the existence or lack of STD, require fasting eight to twelve hours prior to the drawing of the blood sample.

  • Myocardial Ischemia and Infarction

    • The risk increases with age, smoking, high cholesterol levels, diabetes, and high blood pressure, and is more common in men and those who have close relatives with ischaemic heart disease and a history of myocardial infarction.
    • Atherosclerosis is the thickening of the artery wall as a result of plaque formation, which is the accumulation of fatty materials such as cholesterol.
    • These include control of cholesterol levels in those with known high cholesterol, smoking cessation, and control of high blood pressure.

  • Cerebrovascular Accident

    • Examples of risk factors for stroke include high blood pressure, high cholesterol, diabetes, cigarette smoking, lack of physical activity, and obesity.
    • Risk factors for stroke include old age, hypertension (high blood pressure), previous stroke or transient ischemic attack (TIA), diabetes, high cholesterol, cigarette smoking, and atrial fibrillation.
    • Other modifiable risk factors include high blood cholesterol levels, diabetes, cigarette smoking, heavy alcohol consumption, and unhealthy diet.

  • Congenital Adrenal Hyperplasia

    • Congenital adrenal hyperplasia refers to an autosomal recessive disease caused by mutated genes for enzymes that produce cortisol from cholesterol.
    • Congenital adrenal hyperplasia (CAH) refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands (steroidogenesis).

  • Coronary Artery Disease

    • Hypercholesterolemia (specifically, serum LDL concentrations), smoking, hypertension (high systolic pressure seems to be most significant in this regard), hyperglycemia (due to diabetes mellitus or otherwise), and high levels of lipoprotein, a compound formed when LDL cholesterol combines with a substance known as apoliprotein.
    • It is mainly based on age, gender, diabetes, total cholesterol, HDL cholesterol, tobacco smoking, and systolic blood pressure.

  • Aging and the Heart

    • Atherosclerosis is the deposition of cholesterol on and in the walls of the arteries, which decreases blood flow and forms rough surfaces that may cause intravascular clot formation .

  • Bile

    • Bile is a composition of the following materials: water (85%), bile salts (10%), mucus and pigments (3%), fats (1%), inorganic salts (0.7%), and cholesterol (0.3%).