Understanding the Essentials of Blood Lipid Metabolism

Kori J. Kingsbury, RN, MSN, Greg Bondy, MD, FRCPC

In This Article

The Function of Serum Lipids

Lipids serve several important physiologic functions within the human body. For cell membranes, cholesterol provides an essential stabilizing function and facilitates membrane transport. Cholesterol is required for biosynthesis of hormones and is a precursor of adrenal and sex hormones. Cholesterol is also required for the synthesis of bile acids; bile acids are crucial for the absorption of dietary fat in the small intestine. TGs offer an ideal means of energy storage and production; TGs are stored in adipose cells and are light in weight relative to their energy content when compared to glycogen stores in liver or muscle. Cardiac and skeletal muscle cells extract TG transported in circulating lipoproteins and converted to fatty acids and glycerol through lipolysis. Fatty acids are a major energy source for muscle cells. They are broken down in a beta-oxidation reaction and then enter the Kreb's cycle with subsequent production of adenosine triphosphate. In a number of cells, such as muscle and liver cells, fatty acids can also be converted into glucose through gluconeogenesis.