Chapter 5: Lipids
omega-6 fatty acid
A fatty acid containing a carbon-carbon double bond between the sixth and seventh carbons from the omega end.
omega-3 fatty acid
A fatty acid containing a carbon-carbon double bond between the third and fourth carbons from the omega end.
monounsaturated fatty acid
A fatty acid that contains one carbon-carbon double bond.
polyunsaturated fatty acid
A fatty acid that contains two or more carbon-carbon double bonds.
saturated fatty acid
A fatty acids in which the carbon atoms are to as many hydrogens as possible and which therefore contains no carbon-carbon double bonds.
low-density lipoproteins (LDLs)
Lipoproteins that transport cholesterol to cells. Elevated LDL cholesterol increases the risk of cardiovascular disease.
chylomicrons
Lipoproteins that transport lipids from the mucosal cells of the small intestine and deliver triglycerides to other body cells.
fatty acids
Organic molecules made up of a chain of carbons linked to hydrogen atoms with an acid group at one end.
lipoproteins
Particles containing a core of triglycerides and cholesterol surrounded by a shell of protein, phospholipids, and cholesterol that transport lipids in blood and lymph.
*micelles
Particles formed in the small intestine when the products of fat digestion are surrounded by bile acids. They facilitate the absorption of fat.
emulsifiers
Substances that allow water and fat to mix by breaking large fat globules into smaller ones.
lipid bilayer
Two layers of phosphoglyceride molecules oriented so that the fat-soluble fatty acid tails are sandwiched between the water-soluble phosphate-containing heads.
phospholipids
Types of lipids containing phosphorous. The most common are the phosphoglycerides, which are composed of a glycerol backbone with two fatty acids and a phosphate group attached.
sterols
Types of lipids with a structure composed of multiple chemical rings.
phosphoglycerides
A class of phospholipid consisting of a glycerol molecule, 2 fatty acids, and a phosphate group.
essential fatty acid deficiency
A condition characterized by dry scaly skin and poor growth that results when the diet does not supply sufficient amounts of the essential fatty acids. *Rare condition.
cholesterol
A lipid that consists of multiple chemical rings and is made only by animal cells.
*lecithin
A phosphoglyceride composed of a glycerol backbone, two fatty acids, a phosphate group and a molecule of choline. *In the body it is a major constituent of cell membranes and is required for their optimal funcition.
LDL receptor
A protein on the surface of cells that binds to LDL particles and allows their contents to be taken up for use by the cell.
oxidized LDL cholesterol
A substance formed when the cholesterol in LDL particles is oxidized by reactive oxygen molecules. It is key in the development of atherosclerosis because it contributes to the inflammatory process.
tropical oils
A term used in the popular press to refer to the saturated oils--coconut, palm, and palm kernel oil--that are derived from plants grown in tropical regions.
atherosclerosis
A type of cardiovascular disease that involves the buildup of fatty material in the artery walls.
hormone-sensitive lipase
An enzyme present in adipose cells that responds to chemical signals by breaking down triglycerides into fatty acids and glycerol for release into the blood stream.
lipoprotein lipase
An enzyme that breaks down triglycerides into fatty acids and glycerol; attached to the cell membrane of the cells that line the blood vessels.
trans fatty acid
An unsaturated fatty acid in which the hydrogen atoms are on opposite sides of the double bond.
cardiovascular disease
Any disease affecting the heart and blood vessels.
scavenger receptors
Proteins on the surface of macrophages that bind to oxidized LDL cholesterol and allow it to be taken up by the cell.
eicosanoids
Regulatory molecules, including prostaglandins and related compounds, that can be synthesized from omega-3 and omega-6 fatty acids. *Help regulate blood clotting, blood pressure, and other body processes.
essential fatty acids
Fatty acids that must be consumed in the diet because they cannot be made by the body or cannot be made in sufficient quantities to meet needs.
very-low-density lipoproteins (VLDLs)
Lipoproteins assembled by the liver that carry lipids from the liver and deliver triglycerides to body cells.
high-density lipoproteins (HDLs)
Lipoproteins that pick up cholesterol from cells and transport it to the liver so that it can be eliminated from the body. A high level of HDL decreases the risk of cardiovascular disease.
atherosclerotic plaque
The cholesterol-rich material that is deposited in the arteries of individuals with atherosclerosis. It consists of cholesterol, smooth muscle cells, fibrous tissue, and eventually calcium.
beta-oxidation
The first step in the production of ATP from fatty acids. This pathway breaks the carbon chain of fatty acids into two-carbon units that from acetyl-CoA and releases high-energy electrons that are passed to the electron transport chain.
triglycerides (triacylglycerols)
The major form of lipid in food and in the body. They consist of three fatty acids attached to a glycerol molecule.
hydrogenation
The process whereby hydrogen atoms are added to the carbon-carbon double bonds of unsaturated fatty acids, making them more saturated.
adipose tissue
Tissue found under the skin and around body organs that is composed of fat-storing cells.
