Understanding Lipids and Triglycerides

Lipids

• Lipids are the collective name for fats, oils, waxes, and fat-like molecules found in the body, including steroids.
• Lipids fulfil roles such as components of cell membranes (phospholipids and cholesterol), energy stores, chemical messengers (steroid hormones), and agents for protection, waterproofing, insulation, and buoyancy.

Triglycerides

• Triglycerides are esters of glycerol (an alcohol) and fatty acids (long chain carboxylic acids).
• Triglycerides are composed of glycerol and 3 fatty acids.
• Glycerol is a trihydric alcohol, and each molecule has three hydroxyl groups
• Each fatty acid has a carboxylic acid (-COOH) group at one end and a methyl group at the other end.
• Fatty acids are carboxylic acids with a long hydrocarbon tail.
• Fatty acids may be saturated or unsaturated.
• Fatty acids always contain an even number of carbon atoms, typically ranging between 10-20 carbon atoms long.
• Hydrocarbon chains can be either saturated or unsaturated.
• Fats are solids obtained primarily from animals, while oils are liquids obtained primarily from plants.
• Saturated hydrocarbon chains contain only single bonds, appear solid at room temperature, and commonly include animal fats (butter, lard) and tropical oils (palm, coconut).
• Unsaturated hydrocarbon chains contain one or more double bonds and appear liquid at room temperature.
• Monounsaturated fats contain fatty acids with 1 double bond, like canola and olive oil.
• Polyunsaturated fats contain a high percentage of fatty acids with >2 double bonds, for example corn, safflower, soybean, sunflower oils, and fish.
• The glycerol molecule has three hydroxyl groups.
• When one reacts with a fatty acid a monoglyceride forms.
• When two react with two fatty acid molecules a diglyceride forms.
• When three react with three fatty acid molecules a triglyceride forms.
• The number of the omega refers to the position of the double bond nearest the methyl (CH3) end of the carbon chain.
• Hydrogenation is the addition of hydrogen to unsaturated fat to increase stability, make it more solid/firm, and protect against oxidation.
• Most double bonds in nature are cis, meaning the hydrogens next to the double bonds are on the same side of the carbon chain
• When a fat is partially hydrogenated, some of the double bonds change from cis to trans.

Phospholipids

• Phospholipids are a diglyceride in which one of the glycerol binding sites contains a phosphate group.
• In phospholipids, one of the fatty acids of a triglyceride is substituted by a phosphate group.
• Phospholipids play a key role in the structure and properties of cell membranes.
• Functions of phospholipids include acting as a part of cell membranes and as an emulsifier to keep fats in solution.
• Examples of foods with phospholipids: lecithin, egg yolks, soybeans, wheat germ, and peanuts,

Steroids

• Steroids contain a core structure of 17 carbons fused in a ring structure containing 3 six-member rings and 1 five-member ring.
• The different functionalities of steroids come from the substituent groups attached to the core structure.
• Steroids include compounds such as cholesterol, sex hormones, birth control pills, cortisone, and anabolic steroids.
• Cholesterol is the most abundant steroid in the body.
• Cholesterol is formed in brain tissue, nerve tissue, and the bloodstream.
• Cholesterol is a major compound found in gallstones and bile salts.
• Testosterone is the primary male hormone that supports the normal development of male genital organs and is synthesized from cholesterol in the testes.
• Progesterone and estrogen or estradiol are two female sex hormones that control the ovulation cycle.
• Estrogen, along with progesterone, regulates changes occurring in the uterus and ovaries known as the menstrual cycle.
• Adrenocorticoid hormones are a product of the adrenal glands: "adrenal" means adjacent to the renal (kidney).
• Aldosterone regulates the reabsorption of sodium and chloride ions in the kidney tubules and increases the loss of potassium ions.
• Aldosterone is secreted when blood sodium ion levels are too low to cause the kidney to retain sodium ions.
• Cortisol, the most important glucocortinoid, increases glucose and glycogen concentrations in the body.
• Cortisone is a ketone derivative of cortisol used to treat inflammatory diseases, rheumatoid arthritis, and bronchial asthma.