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Chapter 5 The Lipids: Triglycerides, Phospholipids, and Sterols Learning Objectives After completing Chapter 5, the student will be able to: 1. Describe the structure of a fatty acid and the effects of chain length and saturation on the properties of the fat. 2. Describe the triglyceride. 3. List and describe the three types of fatty acids found in foods. 4. Explain the structure of the omega-3 and -6 fatty acids. 5. Explain the roles of phospholipids and sterols in foods and in the body. 6. Trace the digestion of lipids including identification of enzymes needed and the role of bile. 7. Describe the absorption of lipids into the intestine and the formation of the chylomicron. 8. Describe the role of the liver in the production of lipoproteins. 9. Explain the health implications of LDL and HDL and the factors that raise or lower levels of these lipoproteins. 10. Identify the uses of triglyceride in the body. 11. Identify the essential fatty acids and their role in the formation of eicosanoids. 12. Discuss the role of fat in the development of heart disease, cancer and obesity. 13. Explain the recommended dietary intakes for fat, saturated fat, essential fatty acids and cholesterol. 14. Describe the diet recommendations for selection of a diet lower in total fat, saturated fat, trans fat and cholesterol. I. The Chemists View of Fatty Acids and Triglycerides The class of nutrients known as lipids includes triglycerides ( fats and oils ), phospholipids, and sterols. Most are triglycerides with glycerol backbones and three fatty acids attached. Fatty acids vary in carbon chain lengths, degree of unsaturation, and number of double bonds. Saturation affects the physical characteristics of the fat and its storage properties. Trans-fatty acids, which are altered, have the same negative health effects as saturated fatty acids. A. Fatty Acids 1. The Length of the Carbon Chain a. Long-chain fatty acids are found primarily in meat, fish, and vegetable oils. b. Medium- and short-chain fatty acids are found in dairy products. 2. The Degree of Unsaturation a. Saturated fatty acids carry the maximum possible number of hydrogen atoms. When most of the fatty acids are saturated it is called a saturated fat . b. Unsaturated fatty acids lack hydrogen atoms and have at least one double bond. The double bond is considered the point of unsaturation . 1. Monounsaturated fatty acids lack two hydrogen atoms and have one double bond. When most of the fatty acids are monounsaturated it is called a monounsaturated fat . 2. Polyunsaturated fatty acids (PUFA) lack four or more hydrogen atoms and have at least two or more double bonds. When most of the fatty acids are polyunsaturated it is called a polyunsaturated fat . ... View Full Document

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