11SprNTR342-LipidMet1

11SprNTR342-LipidMet1 - Lipid Metabolism 1 Reading: Gropper...

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Lipid Metabolism 1 Reading: Gropper 4 th ed, Ch 6, pp. 138–147, 151–153 Gropper 5 th ed, Ch 5, pp. 144–154, 157–159
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2 Objectives for today: Review lipid absorption and digestion Lipid transport Catabolism of triglycerides and fatty acids
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3 Lipids Chemically diverse Physically similar: hydrophobicity requires special handling in an aqueous environment Emulsification (dispersion as ~ 1 mm droplets) increases relative surface area for enzymatic attack occurs in stomach (muscular contractions) and especially small intestine (stabilized by bile salts and acids)
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4 Lipid Metabolism
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5 Dietary lipids: sources Animal Meat, poultry, fish, eggs Lard, tallow Milk, cheese, cream, butter Plant Nuts, avocados Peanuts and soybeans Vegetable oils Shortening and margarine
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6 Dietary lipids: saturation Fatty acids: Saturated (SFA) Unsaturated (UFA) Monounsaturated (MUFA), Polyunsaturated (PUFA) Animal fats have low P/S ratio Vegetable fats have high P/S ratio Lower melting point (except coconut oil) Adipose and red blood cell membrane P/S ratio reflects diet Useful for compliance in research studies
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7 Major dietary lipids and their digestion products Triglycerides (pancreatic lipase + colipase) 2-monoacylglycerol and free fatty acids; some complete digestion to glycerol Phospholipids (phospholipase A 2 ) Lysophosphatidylcholine (most common) and free fatty acid Cholesteryl esters (cholesteryl esterase) Cholesterol and free fatty acid
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8 Dietary lipids: sterols Animal: cholesterol, cholesteryl esters Plant: phytosterols Compete for incorporation into micelles and displace cholesterol Inhibit cholesterol absorption Used in margarine and spreads Sitosterol (soybean oil; Promise activ ) Sitostanol (pine tree wood pulp; Benecol )
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9
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10 Table 5-3, p. 142
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11 Lipid Absorption Lipid digestion products diffuse into the enterocytes— the micelles themselves DO NOT enter the cells Free fatty acids are reesterified to make triglycerides, phosphatides, and cholesteryl esters rapid metabolism maintains concentration gradient for diffusion from intestinal lumen Short-chain free fatty acids (<10-12 carbons) diffuse directly into the blood
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12 Intestinal mucosal cell Endoplasmic reticulum
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This note was uploaded on 05/10/2011 for the course NTR 342 taught by Professor Tillman during the Spring '09 term at University of Texas.

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11SprNTR342-LipidMet1 - Lipid Metabolism 1 Reading: Gropper...

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