Student Research: Cheryl Oxley
Cholesterol is a waxy material derived from animal and vegetable tissues. It is widely distributed throughout the body, being essential for the production of sex hormones as well as repair of membranes. It is also the source from which bile acids are manufactured. Before cholesterol can perform these functions, it must be processed by the liver, which packages it as cholesterol and protein combinations called lipoproteins - low-density lipoprotein (LDL), very-low-density lipoprotein (VLDL), and high-density lipoprotein (HDL). The amount normally present in the blood of Americans is 150 to 250 mg per 100 ml.
It has been hypothesized that cells needing cholesterol have LDL receptor sites. These sites bind LDL particles, take the LDL into the cells and break it down. This action provides the cell with cholesterol and reduces the LDL level in the bloodstream. The liver is one of the primary sites for LDL uptake, and both excretes cholesterol in the foRMS described above and uses cholesterol to make bile acids. The adrenal glands use cholesterol to make hormones. It is also believed that HDLs provide a means of removal of cholesterol from the tissues, i.e., act as receptor sites and thus decrease the amount of cholesterol in the bloodstream.
The purpose of this study is to determine if obesity affects the total blood cholesterol level, the HDL blood cholesterol level, or the ratio of total to HDL cholesterol level. Obesity is defined as fat, stout, or corpulent and can be measured in teRMS of weight, the ratio of the weight to the square of the height or Body Mass Index (BMI), and percent body fat. These three measures of obesity were evaluated against total blood cholesterol level, HDL blood cholesterol level, and the ratio of total to HDL cholesterol level to determine if there is a correlation between obesity and cholesterol level.