HUN 3224 Test 3 Study Guide of Amazingness Lipids Intro to Lipids Digestion and Absorption 1 Know the concepts surrounding fatty acids saturation cis versus trans configurations nomenclature chain length essentiality a Fatty acids are straight carbon chains ranging from 4 24 carbon chains long i When the chains are over 14 carbons long they are nutritionally significant and also most fats are even numbered b Saturation i Saturated fatty acids means that all carbons are attached without any double bonds therefore double bonds unsaturated ii Monosaturated fatty acids one double bond 1 Examples are olive and canola oil iii Polyunsaturated fatty acids more than one double bond 1 The Cis form of polyunsaturated fats is predominant to the Trans 2 Trans form will show up when hydrogentating unsaturated fats 3 Examples are sunflower soybean and veggie oils c Hydrogenation i Hydrogenation is basic chemistry it is the adding of Hydrogen s to a double bond in order to make it a single bond This is often used in commercially processed foods because its helps keep the shelf life last must longer on fatty foods 2 Be able to name fatty acids a Naming fatty acids is hard and I don t get it 3 Know the functions and examples of eicosanoids triglycerides sterols and phospholipids a Eicosanoids i Eicosanoids are mainly derived from arachidonic acid 1 Modulation of blood pressure platelet aggregation in the immune ii Synthesized from Arachidonate Acid 20 4 6 Eicosatrienoic Acid 20 3 system nervous system and in smooth muscle contraction 6 and Eicosapentanoic Acid 20 5 6 Eicosanoid family Prostacyclins Site of synthesis Vascular endothelium Platelets Leukocytes Endothelium of a variety of cells Mode of Action Vasodilator platelet anti aggregation Vasoconstriction plateley aggregation Vascular contraction inflammation Vascular smooth muscle contraction or relaxation Thromboxanes Leukotrienes Prostaglandins b Triglycerides i Triglycerides are the most common fatty compound in the body 1 One triglyceride is made up of a 3 carbon Glycerol Backbone and three fatty acids simple c Phospholipids i Glycerol backbone ii One or more fatty acid iii One phosphate i Lipid and carbohydrate d Glycolipids e Sterols i Steroid nucleus ii Cholesterol 1 Cholesterol is an essential component for the cell membranes especially nerve tissue and is a precursor for vitamin D and BILE 2 Bile acids 3 Steroidal sex hormones 4 Adrenocortical hormones 5 Vitamin D 4 Be able to discuss lipid absorption into and out of the enterocyte a Lipid Digestion i Lingual lipase lingual tongue 1 Secreted at the base of the tongue and if very efficient in the digestion of milk fats a Babies love milk ii Biliary emulsification 1 Emulsification is the breakdown of large fats into smaller fats thus increasing the surface area for the lipase to work 2 Bile salt is the emulsifying agent iii Lipolysis is the breakdown of fats and there are three main enzymes 1 Pancreatic Lipase a With pancreatic lipase we are able to do this b Triglyceride removal of fatty acid 1 2 diacylglycerol removal of fatty acid monoglycerol removal of fatty acid glycerol a With cholesterol esterase we are able to do this b Cholesterol ester removal of fatty acid free cholesterol 2 Cholesterol esterase 3 Lecithinase a With lecithinase we are able to do this i Lecithin removal of fatty acid lysolecthin b Lipid absorption i Micelle formation what is a micelle 1 A micelle is a bunch of fatty elements and fat soluble vitamins surrounded by bile salts it is a little tiny ball of fat 2 Micelles are absorbed thru enterocytes by passive diffusion concentration gradient at the distal end of the duodenum and the jejunum toward the end of the colon a Bile salts that are absorbed in the ileum are returned to the liver via the EHC or enterohepatic circulation ii Let s take a trip inside the enterocyte 1 Once inside the enterocyte fatty acids and monoglyceride are transported to the endoplasmic reticulum ER where they are used to synthesize triglycerides TGs a Long chain fatty acids 12 C and other fatty components are activated by coenzyme A these are then called fatty components b Short chain fatty acids simply pass to the blood and attach to the large protein molecule albumin 2 Not only are TGs reformed but so are cholesterol esters and phosphates remember those three major lipolysis enzymes from before Inside the ER TGs fatty components proteins all combine to form what is known as a chylomicron 3 Lipoproteins lipoproteins are complexes which carry lipid products in the blood and lymph to various tissues 1 Be able to describe the formation function and breakdown of a chylomicron a Well we just talked about the formation of a chylomicron so let s talk about some other stuff about it Just remember a chylomicron is a type of lipoprotein b c What do chylomicrons do i CHYLOMICRON IS THE LARGEST LIPOPROTEIN AND HAS THE LOWEST DENSITY it s very large but very light like a big balloon ii Mostly made out of triglycerides which are fat Fat is less dense than water thus the more fat the lighter the lipoprotein weighs i Chylomicron travels throughout the blood to various tissues transporting EXOGENOUS triglycerides meaning fats that we have eaten ii Once at the tissues the chylomicron is broken down by Lipoprotein Lipase LPL 1 LPL hydrolyzes TGs into free fatty acids and glycerol 2 These free fatty acids and glycerol is absorbed into the tissues where d What about the left over chylomicron remnants they were brought i The reamainders after TG hydrolysis travel in the blood and are eventually taken up by the hepatocytes liver cells ii The remnants are taken up by hepatocytes via receptor mediated endocytosis remember that 2 Know the relationship between density size and protein for lipoproteins a Basically proteins weigh a lot high density and fats don t weigh much at all low density b The larger the lipoprotein the more fat it has and the less protein it has The smaller the lipoprotein the more protein it has and the less fat it has c Fats are big proteins are small if you get these concepts you will understand the relationships d LARGE LIPOPROTEIN LOW DENSITY high fat low protein e SMALL LIPORPOTEIN HIGH DENSITY high protein low fat f Here is a the order of lipoproteins in order from largest most fat least protein to smallest least fat most protein i Chylomicron VLDL IDL LDL HDL 3 Know the formation and function of each lipoprotein a First we must realize the lipoproteins are surrounded by a specific
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