Lipids are molecules containing hydrocarbons that make up the structure of living cells. The term "lipids" encompasses a variety of substances, including fats, oils, waxes, vitamins, hormones and, in fact, the bulk of the non-protein membranes of cells. Lipids are insoluble in waters, but are soluble in other organic solvents, such as ether, acetone, and other lipids.
Functions of Lipids
Lipids perform several necessary functions in the body, including:
- Providing and storing energy
- Making up part of each cell's membrane
- Functioning as building blocks for hormones and bile
Lipids are also important components of the central nervous system.
Types of Lipids
Lipids are divided into types, differentiated by where they occur in nature and several other factors.
Triglycerides can be solid or liquid at room temperatures. In solid form, they are known as fats; in liquid form, they are referred to as oils. Triglycerides can be saturated or unsaturated, and unsaturated fats are further subdivided into mono -or- polyunsaturated.fats. Saturated fats are found primarily in animal fat, whereas monounsaturated fatty acids are found in vegetable oils.
Saturated fats raise low density lipoprotein (LDL, or "bad") cholesterol blood levels, while unsaturated fats lower them. This is the reason that saturated fats increase a patient's risk of cardiovascular disease, and unsaturated fats reduce that risk.
Fat should never be eliminated from the diet, however, since adipose (fatty) tissue performs an essential function. Adipose tissue not only stores energy for future use, but also helps to insulate the body, and to cushion and protect the organs and bones.
Phospholipids are the building blocks of cellular membranes. They are comprised of two regions: the head region, which is attracted to water (hydrophillic) and the tail region with is repelled by water (hydrophobic). As a primary component of cell membranes, phospholipids are responsible for enclosing the cytoplasm and other elements of the cell.
Steroids and Waxes
Steroids include cholesterol, sex hormones, and cortisone, a steroid. Unlike most waxes, ear wax is composed of phospholipids and cholesterol.
Organic polymers include natural lipids, such as silk, cellulose, and natural rubber. They also make up the protein of DNA and RNA.
Lipids are also the building blocks of fat-soluble vitamins, such as vitamins A, D, E, and K, all essential to health and proper function.
Lipids is a broad category, taking in a wide variety of substances.
A lipid panel is a blood test used to measure the level of cholesterol and lipids in the body. This test is administered to help assess an individual's risk of developing cardiovascular disease. Adults over the age of 20 are advised to have this test every 5 years. Patients at increased risk, due to family history of heart disease, obesity, or diabetes, are advised to take the test more frequently.