LIPIDS I Fatty Acids A Straight chain hydrocarbon chain Methyl group at one end carboxyl group on the other 1 Fatty acids are 4 24 C s long and most are an even number chain 2 14 nutritionally significant B Saturation 1 Saturated Fatty Acids All C s saturated with H s a NO double bonds Saturated fats are solid at room temp and are usually from animals or tropical plants 2 Monosaturated a One double bond b Olive and canola oil 3 Polyunsaturated a Multiple double bonds C Hydrogenation 1 Adding H s to unsaturated fat to make it solid at room temp a Crisco process left trans double bonds 2 Forms trans fats found in processed foods D Nomenclature CH3 end omega or n COOH end alpha or delta Naming 1 count of carbons 2 Count of double bonds 3 Name according to alpha or omega end DOUBLE BONDS ARE ALWAYS 3 CARBONS APART KNOW HOW TO SEE A FAT AND NAME KNOW HOW TO DRAW FATTYA FROM NAME DON T COUNT DOUBLE BOND FROM CARBOXYLIC ACID E Essential Fatty Acids 1 Linoleic Acid 18 2 6 or 18 2 9 12 2 Linoleic Acid 18 3 3 or 18 3 9 12 15 We lack enzymes to add a double bond beyond 9 II Eicosanoids involved in fever and raising body temp a Blood pressure Platelet aggregation Immune and Nervous Systems and Smooth muscle contraction A Hormone like substance 1 Modulation of B Families 1 Prostacyclin 2 Thromboxane 3 Leukotrienes C Synthesized from 1 Arachidonate Acid 20 4 6 2 Eicosatrienoic Acid 20 3 6 3 Eicosapentanoic Acid 20 5 3 D Characteristics of Eicosanoids Eicosanoid Family Protacyclins Site of Synthesis Vascular Endothelium Platelets Leukocytes Mode of Action Vasodilator platelet anti aggregation Vasoconstrictor aggregation Vascular contraction inflammation Endothelium of a variety of cells Vascular smooth muscle relaxation or contraction Thromboxane Leukotrienes Prostaglandins III Triglycerides IV Phospholipids V Glycolipids VI Sterols A Glycerol Backbone 3 Carbon chain 3 Fatty Acids FA A Glycerol backbone 1 or more FA 1 Phosphate Usually Unsaturated usually in cell membranes A Lipid and carbohydrate Usually in cell membrane and used for signaling Don t provide energy A Steroid nucleus B Cholesterol 1 Bile acids 2 Steroidal sex hormones 3 Adrenocortical Hormones 4 Vitamin D UV B rays turn cholesterol into Vit D W o cholesterol cell membranes would fall apart Cholesterol is only found in animal products LIPID DIGESTION I Lingual Lipase A Secreted at base of tongue B Stable at low pH C Efficient digestion of milk fat for infants II Biliary Emulsification A Emulsification 1 Dispersion of fat in an aqueous solution 2 Allows for lipase action B Bile salt emulsifying agent 1 One end hydrophilic other is lipophilic III Lipolysis Three main enzymes A Pancreatic Lipase 1 Breaks fatty acid from glycerol backbone Triglyceride 1 2 dialglycerol Fatty Acid Monoglyceride Fatty acid Glycerol Fatty Acid B Cholesterol Esterase 1 Breaks ester bond to pull FA from cholesterol molecule Cholesterol Ester Free Cholesterol Fatty Acid C Lecithinase 1 Breaks down phospholipids Lecithin Lesolecithin Fatty Acid LIPID ABSORPTION I Micelle Formation II Inside the Enterocyte A Fatty elements and vat soluble vits surrounded by bile salts B Passive diffusion of fatty elements and vitamins at distal duodenum and jejunum C Bile salts absorbed in ileum and returned to liver via EHC A Long chain FA 12 and other fat components activated with coenzyme A Reformation of TG s cholesterol esters and phospholipids TG s fatty components proteins chylomicron D Short chain fatty acids attach to Albumin and takes them to the blood Fat encapsulated in bile so it doesn t emulsify Fatty part diffuses to enterocyte and reforms all elements listed We then add a protein to make a chylomicron Chylomicron goes into lacteal of lymph thoracic duct blood fat to blood LIPOPROTEINS Complexes which carry lipid products in the blood and lymph to various tissues Single phospholipid membrane I Chylomicron A Synthesis in enterocyte from exogenous lipids and released into the lymph B Composition 1 Mostly triglycerides 2 Some apoproteins phospholipids and cholesterol USED to carry TG s from the fat that we eat C Largest lipoprotein with lowest density D Function 1 Transport exogenous TG to tissues ones we eat 2 Lipoprotein Lipase LPL a Hydrolyzes TG to break down fatty acids and glycerol b Free FA s and Glycerol absorbed into tissues E Chylomicron Remnant 1 Remains after TG hydrolysis 2 Taken up by hepatocytes via Receptor Mediated Endocytosis RME Chylomicrons full of TG LPL pulls those out and breaks them down cells then take what they need Chylomicron remnant uses EMR into the liver HDL made by liver and takes cholesterol ester from cells back to liver The liver then makes VLDL LPL IDL LPL LDL LDL carries only cholesterol and used RME to get into the cells If there s a lot of LDL in cell we turn off enzyme that allows LDL in The remaining LDL remains outside the cells II Very Low Density Lipoprotein VLDL A Synthesized in liver and released into blood Can be made from liver fat or chylomicron remnant B Composition 1 Mainly used to carry TG s 2 Carries cholesterol phospholipids and apoproteins as well C Slightly smaller than Chylomicron D Function 1 Transports endogenous lipid body fat from liver to extra hepatic tissues a Extra hepatic tissue any tissue that isn t the liver 2 Lipoprotein Lipase LPL a Hydrolyzes TG to free fatty acids and glycerol III Intermediated Density Lipoprotein IDL A From VLDL after TG hydrolysis 1 Transient and very short lived B Formed into LDL after TG hydrolysis via LPL IV Low Density Lipoprotein A From IDL after TG hydrolysis B Delivers cholesterol to non hepatic tissues Uptake via RME C Composition 1 Mostly cholesterol 2 Some apoproteins phospholipids and TG s D Smaller than LDL E Receptor Mediated Endocytosis Receptors located in Calatharin promotes binding of a molecule to the receptor This receptor only takes Apo B 100 Cell membrane surrounds LDL receptor complex and brings it in Lysosomes bind to receptor and changes pH Proteins of lipoproteins are released as AA s Cholesterol also leaves Receptor returns to surface and waits for next LDL 1 Regulation a HMG CoA reductase activity Rate limiting enzymes for cholesterol synthesis More cholesterol decreased enzyme activity b LDL receptor synthesis If cholesterol levels in cell are high decreased receptor synthesis If cholesterol is high it s because cells are saturated with cholesterol and LDLs are in blood Longer LDL s are in blood more likely to be damaged If LDL s are damaged in
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