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41 Cards in this Set
- Front
- Back
What are Lipids/fats? |
- a family of compounds insoluble in water. - Fat is solid at room temp - Oils are liquid at room temp |
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Why are fats needed for good health? |
- Some fatty acids are essential nutrients - carry fat soluble vitamins - provide energy - increase satiety value of foods - enhance taste and aroma - provide moisture |
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Why are lipids absolutely necessary? |
- serve as energy source especially for muslces - contribute to a feeling of fullness at a meal by slowing digestion - enhance foods aroma and falvour - cushion the vital organs - prtoect the body from extreme temperature - carry fat soluble vitamins ADEK - provide essential fatty acids as part of fat - Provide the major material of which cell membranes are made |
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What is the function of fat in the body? |
- Provide compact energy reserves - major consitituent of cell membranes - cushion organs -assist in temperature regulation |
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What is the difference between visceral and subcutaneous fat? |
- Visceral: surrounds organs. affected by diet and excersise - Subcutaneous: thin layer beneath the layer of skin |
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What is the difference between gynoid and android adiposity? |
Gynoid: fat distributed more around hips and but Android: fat distributed around stomach. |
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What are adipose cells? |
- store fat - can vary in number and size |
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What about enzymes that are related to fat? |
- LPL: lipoprotein lipase - HSLPL: hormone sensitive lipoprotein lipase |
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What are the 3 classes of lipids? |
1. Triglycerides (TG) - fats and oils . 95% of lipids in foods and humans are TG. energy reserves. 2. Phospholipids - lecithin in one phospholipid. cell membranes, many special functions (eyes, nerve sheath) 3. Sterols - Cholesterol is best known. cell membranes, steroid hormones, bile salts, vitamin D. |
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What are Triglycerides? |
- 95% of fat in food and body - Made up of glycerol and 3 fatty acids (3 C's) |
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What is the composition of a fatty acid? |
- The length: the more carbon atoms a fatty acid contains the longer it is. 8-22 carbons. usually even. can be saturated, monounsaturated, and polyunsaturated. - The degree of saturation: the more hydrogen atoms a fatty acid contains the more saturated it is. |
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What are the 2 kinds of fatty acid? |
1. Saturated - every body from carbons is holding a hydrogen. 2. Unsaturated - a fatty acid in which a bond from a carbon has an empty spot where hydrogens are missing. Mono: one point of unsaturation. Eg olive oil or canola. May have heart benefits. Poly: two or more points of unsaturation. |
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Which oils are saturated (hard) and which are unsaturated (soft)? |
- animal fat is saturated - vegetable and fish are unsaturated with the exception of coconut (heart harm) and palm oil - soft fats consist of fatty acids that are shorter and more unsaturated which melt more easily or have a low melting point - hard fats consist of fatty acids that are long and more saturated and have a higher melting point. |
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What are essential fatty acids? |
- Some fatty acids must be obtained in food. We canoot make them or we cannot make them in sufficient quanitites to meet out bodys needs. - Linoleic acid = omega 6 fatty acid = C:18:2 w-6 - arachiconic acid = C20:4 w-6 - Linolenic acid = omega 3 fatty acid = C18:3 w-3 - EPA = 20:5 w-3 - DHA = 22:6 w-3 - Regulate blood pressure, blood clot formation, blood lipids, immune response - body can make longer chain members of either family if the 18 carbon form is available. - the body cannot convert from one family to another. - used to make eicosanoids which are biologically active compounds involved in the above things. |
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What is hydrogenation of fats? |
- makes unsaturated fats more saturated - makes liquid fats more chemically stable (useful for making stable fats and deep frying) - males liquif fats more solid which is useful for making fats you can spread and useful for making vegetable shortening. |
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Describe double bonds in terms of fats. |
- tend to be cis in nature - process of hydrogenation can create trans double bonds |
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What are sterols? |
- a class of lipids with complicated structure similar to cholesterol. - cholesterol plays roles as part of the emulsifier called BILE and is used to make other sterols like vitamin D and steroid and sex hormones. - cholesterol is part of brain cells and nerve cells |
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Describe fat digestion. |
1) Mouth: particle size decreases. lingual lipase (in stomach and infants) converts triglycerides to diglyercides and fatty acids. 2) Stomach: TG enter where very little digestion takes place. 3) Small intesine LUMEN: bile salts released to emulsify fat. (also recirculation of bile salts). Pancreatic lipase released to digest fat into monoglycerides and 2 fatty acids. |
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What are the products of fat digestion? |
- glycerol - monoglycerides - Individual fatty acids: some long chain, some medium chain, and some short. |
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Describe the absorption of fats. |
- Intestinal cells absorb fats but they must get across the watery mucus membrane. - small lipids can travel alone in the blood after absorption. glycerol and short and medium (10-12 or less) go directly in blood. - LARGE lipids must be incorperated into transport molecules in order to pass across cell membranes. - collectively, transport molecules for fats are called lipoproteins. MICELLS AND CHYLOMICRONS |
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How do long chain fatty acids and monoglycerides get into the lymphatic system? |
- get surrounded by bile and form a MICELLE to get into the intestinal cell - inside the cell they are bonded to glycerol and reassemble into triglycerides. - now they join with other fats such as cholesterol, phospholipids and also protein (attract both fat and water becuase they are emulsifiers) to form a lipoprotein - the lipoprotein formed into the intestinal cell is a CHYLOMICRON |
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What are not absorbed into the blood? |
- monoglycerides and long chain fatty acids. - instead go into lymphatics or lymph - go through the thoracic duct. |
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Describe how lipoproteins work to get fat into the blood? |
- transport triglycerides, cholesterol, phospolipids and protein, - first in lymphatics - then into the blood circulation at the thoracic duct at the back of the heart where the lymphatic circulation system joins the blood circulation system. |
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What is a Chylomircon? |
- special lipoprotein that carries fat from the small intestine to the body cells and liver. |
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What about bile? |
- some is absoribed into the blood and resused - some is excreted in feces. |
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What is the composition of lipoproteins? |
- they carry lipids in the blood - made up of a phospholipid coat, proteins in coat act as identifying markers, have a TG and Cholesterol core. |
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What is the density of lipoproteins? |
- the higher the protein content of the lipoprotein the higher the density. |
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What are the different types of lipoproteins? |
- cholymicrons. - very low density lipoprotein VLDL - intermediate density lipoprotein IDL - low density lipoprotein LDL - high density lipoprotein HDL |
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Further describe chylomicrons. |
- large particles - mainly triglycerides - formed in the intestinal cell - found in high concentrations after a high fat meal - cleared from the blood within 12-14 hours - as they pass by, body cells remove fat from chylomicrons - LPL - remnants picked up by the liver cells. |
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Describe VLDL. |
- made by liver cells - largely composed of triglycerides 55-65% - smaller quantities of cholesterol, phospholipids and protein - breakdown into IDL before becoming LDL |
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Describe IDL. |
- formed in the plasma during the conversion of VLDV to LDL - contain considerable amounts of triglyceride and cholesterol. |
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Describe LDL. |
- Derived from the conversion of CLDL to IDL as body cells remove triglycerides from them. - Around half of LDL is composed of cholesterol - The contents of LDL is available to all cells - More lipid, less protein. |
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Describe HDL |
- Synthesized in the liver and intestine. - picks up cholesterol from tissues and sens it to the liver largely composed of protein, and less lipid - increased amounts of HDL protect against atherosclerosis - high density |
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What do trans fatty acids do? |
- raise LDL in blood - lower HDL in blood - Increase oxidation of fat in LDL so increase heart disease. |
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What is Atherosclerosis? |
- inflammatory process causing plaques to accumulate on and in the walls of blood vessels - it changes the functional capacity of the blood vessels (blood flow and elasticity: arteriosclerosis (hardening of arteries)) - a thrombus is a blood clot. if it blocks a vessel in the heart can cause a heart attack of myocardinal infarction. - if blockage occurs in the brain = stroke |
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What are Fat Replacers? |
- Simplesse: digested and absorbed and contributes on 4 calories per gram - Olestra (sucrose plus eight fatty acids): not digested and absorbed. 0 calories. has side effects causing cramps, and pooing. binds vitamin E and K, so not approved in Canada. - Long term effects unknown. |
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Describe the Use of stored fat for energy. |
- when low on fuel and cells need energy, the cells call on stored fat for energy - TG stored in cells break down to FA and glycerol and on to CO2 and H20 and ENERGY (beta oxidation) - glucose is necessary for complete breakdown of fat. Fat fragments combine with fragments of glucose - without carbs, ketosis occurs. |
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What does food cholesterol have to do with blood cholesterol? |
- to control blood cholesterol with diet: - lower total fat in diet - lower saturated fat in diet - lower trans fat - lower cholesterol - eat foods that contain Vitamin D and E as these are antioxidants (control for the oxidation of fat in LDL) - Saturated fats in foods raise blood cholesterol more than cholesterol. |
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What should we concentrate on? |
- having moderate fat consumption - too high = increased body fat leading to increased LDL cholesterol - too low = decreases intake and absorption of fat soluble vitamins. decreases essential fatty acids. possibly decreases HDL cholesterol. - reducing saturated fat = high intake of LDL cholesterol - Reducing trans fats = do it. they are horrible. - want moderate PUFA intake: most chemically reactive fats. (n6 and n3) pufas are the efas. |
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How much fat do we need? |
- recommended: no more than 35% of energy from fat and no more than 10% of energy from saturated fat. |
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Describe good vs. Bad lipoproteins. |
- LDL - contains little protein and mostly cholesterol. transports cholesterol and fats from liver to cells. BAD because when high increases risk of heart attack - HDL - high protein. brings cholesterol from teh cells back to liver. GOOD becuase lowers risk of heart attack. |