4/15

• lipids are organic, meaning they are made of carbon and hydrogen
• most lipids are hydrophobic, meaning they are not miscible in water
• lipids are not soluble in water or water based solvents
• lipids are soluble in organic solvents
• lipids are non-polar and non-ionic, meaning that lipid bonds will be covalent
• in the body, lipids protect, insulate, regulate, serve as vitamins, provide structure, and provide energy
• fats or lipids surround and protect organs and organ systems
• lipids provide insulation in that a layer of subcutaneous fat slows down heat loss in cold weather
• lipids provide insulation in that motor neurons are surrounded by myelin sheaths of lipids, which help speed the impulse
• lipids regulate in that fat based hormones control and regulate reproduction
• an example of a fat based hormone are prostoglandins, which are made up of omega 3 and omega 6 fatty acids
• prostaglandins help regulate inflammation and tissue repair
• Vitamin A - forms retinol
• Vitamin D - promotes calcium uptake
• Vitamin E - promotes wound healing
• Vitamin K - necessary for clotting
• lipids provide structure, in that phospholipids provide a border to the cell and cholesterol is inserted between some borders to provide rigidity
• lipids function as a storage form of energy, in that approximately 90% of the body's stored fuel is lipids
• the other 10% of stored energy is stored as glycogen
• dietary fats are not digested until they reach the small intestine
• • Bile salts emulsifies large lipid droplets to smaller ones
• bile salts are secreted by the liver and stored in the gallbladder
• when bile salts are needed, they are released in the small intestine
• • Lipase digests some lipid molecules (trigylcerides) into free fatty acids and glycerol 
• bile will form a micelle around fats
• • At subclavian vein, lymphatic system drains into blood
• Amphipathic - have both hydrophilic and hydrophobic portion E.g. phospholipid membrane
• saturated fat - had all single bonds; all carbons are saturated with hydrogens

  
• unsaturated fats are missing one or more hydrogens

  
• monounsaturated fats - missing one hydrogen; one double bond
• polyunsaturated fats are missing two or more hydrogens; two or more double bonds
• Cis unsaturated fat - hydrogens are on the same side of the double bond; exist in fluid form as electrons on hydrogens repel each other; causes structures to “bend” not rigid

  
• in our bodies, phospholipids exist as cis unsaturated fats so they are fluid and not rigid
• cis unsaturated fats exist in nature as oils
• natural cis unsaturated fats include sesame oil, olive oil, canola oil
• • Trans-unsaturated fats - occurs when we make a saturated fat into an unsaturated fat; do not exist in nature
• trans-unsaturated fats exist as solids
• trans-unsaturated fat

  
• trans-unsaturated fats tend to generate free radicals - unpaired electrons; cause mutations and therefore cancer
• Hydrogenated - taking an unsaturated fat and making it saturated