lipids

• lipids are hydrophobic and dissolve readily into other lipid and inorganic solvents
• fat is stored in adipose tissue as a triglyceride
• a fatty acid has a hydrophilic carboxylic acid head and a hydrophobic hydrocarbon tail, which is usually around 4-36C long, and a methyl (omega) end
• saturated fatty acids have no double carbon bonds in the hydrocarbon chain so they can be synthesised
• saturated fatty acids are broken down by adding 2 carbons at the beta carbon
• mono-unsaturated fatty acids have one double bond in the hydrocarbon chain and are considered non essential
• the double bond in unsaturated prevents phosphate groups from packing tightly together
• polyunsaturated fatty acids have 2 or more double bonds, 3 atoms apart, some are considered essential
• omega 3 and 6 must be obtained from the diet
• omega 3 is required for development of nervous system and retina
• omega 6 is a key component in phospholipid membranes
• c20 is considered essential as there needs to be enough C18 to produce them
• TG are formed from the condensation of 3 fatty acids with 1 glycerol
• increased visceral fat is associated with increased disease risk
• lipolysis releases glycerol and fatty acids into circulation
• lipolysis requires oxygen for beta oxidation
• triglycerides have twice the amount of energy compared to CHO and AA
• cholesterol contains 4 aromatic rings with a short hydrocarbon tail
• cholesterols are the main component of plasma membranes, bile, and they help produce steriods and vitamin D
• phospholipids contain a glycerol, 2 fatty acids, and a phosphate group
• cholesterol sits in cell membrane to help with fluidity
• eicosanoids are involved in blood clotting, immune system, and blood pressure
• eiocosanoids are made as required from 20-C polyunsaturated FA that are cleaved from the cell membrane
• lipids can be transported by albumin or lipoproteins
• lipoproteins contain triglycerides, phospholipids, cholesterol, and protein
• chylomicrons are formed in the small intestine and transport dietary fat from small intestine to tissues
• after the TG has been removed from the chylomicron, the rest circulates to the liver
• the liver packages excess lipids into VLDL for delivery to body cells and adipose tissue for storage
• LDL contain large amounts of cholesterol and are transported around the body
• HDL contains a high amount of protein and binds to cholesterol to transport to the liver. this is the good cholesterol
• when required, adipose cells release FFA into the blood
• Hormone sensitive lipase is the enzyme in adipose tissue that increases TG breakdown, activated by glucagon, and inhibited by insulin
• lipids have less polar bonds than carbs as they have less oxygen
• hydrophobic hydrocarbon chain is usually 4-36C in length
• monounsaturated example

  oleic acid
• polyunsaturated example

  alpha-linolenic acid
• omega 6 example

  linoleic acid
• triglycerides are stored anhydrously
• cholesterol is non-essential
• unsaturated FA decrease the risk of CVD