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Chapter 6 Lipids

Chapter 6 Lipids. Objectives: Describe the lipids of major biological importance; their basic structure and function Understand how lipids are digested and absorbed by the GI tract; how they are transported and stored in various locations

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Chapter 6 Lipids

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  1. Chapter 6 Lipids • Objectives: • Describe the lipids of major biological importance; their basic structure and function • Understand how lipids are digested and absorbed by the GI tract; how they are transported and stored in various locations • Understand how lipids are packaged into various types of lipoproteins; how these lipoproteins can be distinguished from one another, and how they are related to cardiovascular disease. • Learn how the major lipids are metabolized via b oxidation, how ketones are formed, and how we regulate the manufacture and breakdown of cholesterol • Understand how lipid metabolism is regulated, and how diet and pharmaceutical aids target this regulation • Learn how some fats are “good” for you and can potentially prevent disease • Learn about the thermogenic capacity of brown fat and how it differs from yellow fat

  2. By 2020 about one in five health care dollars spent on people ages 50-69 could be consumed by obesity-related medical problems -- up about 50 percent from 2000. • The proportion of health care expenditures associated with treating the consequences of obesity would increase from 14 percent in 2000 to 21 percent in 2020 for 50-69 year-old men, and from 13 percent to 20 percent for women in the same age group. • Many of the improvements in health achieved by middle-aged and older Americans in recent decades as a result of medical advances could largely be erased over the next two decades if population weight continues to increase.

  3. White Adipose 06CO, p. 128

  4. Fats with Structural or Biological Importance • Fatty Acids • SFA • MUFA • PUFA • Essential fatty acids • N-3 fatty acids (w-3 FA)

  5. SATURATED (SFA) MONOUNSATURATED (MUFA) CIS VS. TRANS Fig. 6-1, p. 130

  6. Partially hydrogenated Deep fat frying

  7. Essential Fatty Acids • Linoleic • alinolenic Δ12 and Δ15 desaturases Fig. 6-2, p. 130

  8. N-3 fatty acids or Omega-3-fatty acids • (EPA – eicoapentaenoic acid, and DHA – docosahexaenoic acid) • Hypolipidemic effects • Antithrombotic effects

  9. Table 6-1, p. 131

  10. Triglycerides medium chain triglycerides - weight gain - athletic performance Fig. 6-3, p. 132

  11. Sterols Fig. 6-7, p. 133

  12. Fig. 6-8, p. 134

  13. Phospholipids (two types) • 1. Glycerophosphatides • phosphatidylcholine (lecithin) • -protection from alcoholic cirrhosis • -synthesis of eicosanoids • phosphatidylserine (rice & GLVs) • -”brain booster” (beware viruses) • - athletic performance • phosphatidylinositol (whole, unprocessed grains, citrus fruits cantaloupe, brewer’s yeast, unrefined molasses, and liver. It is also available in wheat germ, lima beans, raisins, peanuts, cabbage, and some nuts) • -anchoring membrane proteins • -synthesis of eicosanoids Fig. 6-11, p. 135

  14. Virgin Olive Oil vs. Lite Olive Oil vs. Extra Virgin Olive Oil • All virgin olive oils are extracted mechanically from the olives. No processing or other processes other than filtering have been done to the oil. • Virgin vs. Extra Virgin refers to the concentration of oleic acid present in the oil. The oleic acid lowers the pH. The lower the pH, the less “taste” of the olive is present. • Olive oil is monounsaturated and has to be heated to very high temperatures to be converted to its trans form. This is highly likely in industrial fryers, but relatively unlikely to happen on the cooking stove in a home.

  15. PGH2 synthases = Cox1 and Cox 2

  16. Table 6-5, p. 160

  17. Sphingolipids • Sphingomyelins Fig. 6-9, p. 134

  18. Intestinal mucosal cell Endoplasmic reticulum Glycerol Glucose Apoprotein a-GP Cholesterol CHOL Micellar particles CE Free fatty acids FA-CoA Lymphatics MG TG Monoacylglycerols Lysophosphatidylcholine LYSPC PC HDL CHYLO (direct absorption) Short-chain FFA Albumin FA-albumin Portal circulation Lipid Transport and Storage Fig. 6-16, p. 139

  19. Peripheral apoprotein (e.g., apoC) Phospholipid Free cholesterol Cholesteryl ester Triacylglycerol Core of mainly nonpolar lipids Integral apoprotein (e.g., apoB) Monolayer of mainly polar lipids Fig. 6-17, p. 140

  20. Table 6-3, p. 140

  21. LCAT = lecithin:cholesterol acyltransferase Table 6-4, p. 141

  22. Fig. 6-18, p. 142

  23. Fig. 6-19, p. 143

  24. Fig. 6-20, p. 144

  25. Metabolism of Circulating Lipoproteins • Things to remember: • LDLs are the major carrier of cholesterol to tissues, where it may be used for membrane construction or converted into other metabolites. • HDLs remove cholesterol from cells and other lipoproteins and return it to the liver for excretion in the bile.

  26. How cells know whether to take or give away cholesterol 1.pHMG CoA (b) (a) reductase LDL receptor (coated pit) 2.qACAT LDL Cholesteryl oleate Cholesteryl Linoleate Protein Cholesterol 3.pLDL receptors Lysosome Amino acids Regulatory actions LDL binding Lysosomal hydrolysis Internalization Fig. 6-21, p. 145

  27. Macrophage [N]LDL Arterial lumen Platelets MC Endothelium EI [O]LDL [O]LDL PDGF Intima Foam cells Macrophage Smooth muscle cells p. 166

  28. Major Metabolic Pathways for Fat Metabolism • Catabolism • Fatty Acids • Catabolism via b oxidation in mitochondrial matrix • Formation of ketone bodies • Cholesterol • Esterification and bile acid synthesis • Synthesis • Fatty Acids • Cholesterol • Triglycerides

  29. Fig. 6-23, p. 151

  30. Fig. 6-34, p. 161

  31. Fig. 6-35, p. 163

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