|
|
| |
LDL Cholesterol |
| |
Cholesterol which is contained in or bound to low density lipoproteins (LDL); LDL transport cholesterol to peripheral
tissues and regulate de novo cholesterol synthesis at these sites. Atherosclerosis is caused by the deposit of cholesterol
on the walls of blood vessels, because of high concentrations of LDL cholesterol in plasma. Low-density lipoprotein (LDL)
transports cholesterol from the liver to the tissues of the body. LDL cholesterol is therefore considered the "bad" cholesterol.
LDL cholesterol is called "bad" cholesterol, because elevated LDL cholesterol is associated with an increased risk of
coronary heart disease. LDL lipoprotein deposits cholesterol on the artery walls, causing the formation of a hard,
thick substance called cholesterol plaque. Over time, cholesterol plaque causes thickening of the artery walls and
narrowing of the arteries, a process called atherosclerosis. Arteries that supply blood and oxygen to the heart muscles
are called coronary arteries. When coronary arteries are narrowed by atherosclerosis, they are incapable of supplying
enough blood and oxygen to the heart muscle during exertion. Lack of oxygen (ischemia) to the heart muscle causes
chest pain, also formation of a blood clot in the artery can clause complete blockage of the artery, leading to death of
heart muscle (heart attack). Atherosclerotic disease of coronary arteries (coronary heart disease) is the most common
cause of death in the United States, accounting for about 600,000 deaths annually.
HDL is called the "good cholesterol" because HDL cholesterol particles prevent atherosclerosis by extracting cholesterol
from the artery walls and disposing of them through the liver. Thus, high levels of LDL cholesterol and low levels of HDL
cholesterol (high LDL/HDL ratios) are risk factors for atherosclerosis, while low levels of LDL cholesterol and high level
of HDL cholesterol (low LDL/HDL ratios) are desirable.
What determines the level of LDL cholesterol in the blood?
The liver not only manufactures and secretes LDL cholesterol into the blood, it also removes LDL cholesterol from the blood.
To remove LDL cholesterol from the blood, the liver relies on special proteins called LDL receptors that are normally
present on the surface of liver cells. LDL receptors snatch LDL cholesterol particles from the blood and transport them
inside the liver. A high number of active LDL receptors on the liver surfaces is associated with the rapid removal of LDL
cholesterol from the blood and low blood LDL cholesterol levels. A deficiency of LDL receptors is associated with high LDL
cholesterol blood levels.
|
| |
 |
| |
|
Home | Glucose
|
| |
|
