LIPIDS

The lipids are a large and diverse group of naturally occurring organic compounds that are related by their solubility in nonpolar organic solvents (e.g. ether, chloroform, acetone & benzene) and general insolubility in water. There is great structural variety among the lipids, as will be demonstrated in the following sections. You may click on a topic listed below, or proceed page by page.

Lipids including fatty acids (that make up fats and oils), steroids (including cholesterol), phospholipids, and night. One of the functions of lipids in the body is to serve as an energy reserve, while the other serves as a component of the cell structure. However, other lipids act as
hormones and signaling molecules. Thus, the role lipids play in the human body depends on the structure and chemical composition.

Energy storage
Although the human body is easier and more efficient energy derived from carbohydrates, fats provide more energy per gram of potential, allowing for greater storage capacity. Lipids are stored in adipose tissue, which humans like to refer to as "fat". Adipose tissue also serves as a protective cushion for the organ, and a layer of insulation against heat loss.

When lipids are ingested, they are metabolized in the intestine into chylomicrons. This protein-lipid molecules are transported into the cell by other lipoproteins for use or storage, depending on the needs of the body. Liver regulate lipid concentrations in the blood, the excess lead levels in adipose tissue deposition. Lipids stored as triglycerides, which are chemically composed of three fatty acid chains. The process of metabolism, destruction, and recycling are presented in this tutorial with the University of Vermont.

Transportation
Lipids are involved in the transport of other lipoprotein lipids, best known as LDL, HDL, and VLDL. This lipid molecule protein cholesterol, which may be most famously known in relation to the level of LDL ("bad cholesterol") and triglycerides in the blood as a risk factor for heart disease. The lipoprotein named based on how compact they are - low density (LDL), high density (HDL), and very low density (VLDL). To overcome the accumulation of other lipoproteins, HDL acts like a sponge, absorbing excess lipids and cholesterol in physiological processes.

The cell structure

Phospholipid bilayer to form cell membranes, making them essential to human life, mammals, and even eukaryotic. This tutorial from Davidson College shows the structure of the plasma membrane in detail. Chemical characteristics of phospholipids allows them to create a semi-permeable membrane that allows only certain molecules through to the inside of the cell. This rule applies even to water, allow for compartmentalization of cells and controls their transport across membranes.

Research has even found that the lipids in the cell membrane serves an important function in cell signaling and enzyme activity in cellular processes. A new path of inquiry lipid rafts - membrane lipids concentrated area that appears to play an important role in the regulation of genes and other cell signaling events.

Sex hormones and vitamins
Cholesterol is a steroid and serves as a precursor for androgen - better known as sex hormones, and vitamin D and cortisol, a stress hormone. According to the University of California, only about 15 percent of the cholesterol in the human body is swallowed. Rensselaer Polytechnic offers a visual representation of the full chemical pathway for the synthesis of cholesterol.

Lipids in the brain
Membranes of the brain and nervous system are made of lipids. Although the brain does not have triglycerides, lipids play an important role in signal transduction and protein retention, as discussed in Basic Neurochemistry. Because of the prevalence of membranes in the nervous system, high concentrations of lipids found in the system. In recent years, research has found that many neurological disorders may actually have some basis in lipid imbalance. As the understanding of the physiological process involving the increase of lipids, their importance more clearly in the human body becomes.