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45 Cards in this Set
- Front
- Back
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What are the main functions of lipids?
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- Energy source
- Structure and protection - Insulation - Transport (lipoproteins) - Signalling molecules & hormones - Immunity & inflammatory response |
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How if fat stored?
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- In adipose tissue (subcutaneous & visceral stores)
- Muscle (as triglyceride) |
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Types of lipids:
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- Triglycerides
- Phospholipids - Cholesterol - Eicosanoids |
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What is the basic fatty acid structure?
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Consist of:
- hydrophilic carboxylic acid group - Hydrophobic hydrocarbon chair (4-36 C in length) - Methyl end (omega (w) C-atom) |
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What is a saturated fatty acid?
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Has no C=C double bonds in the hydrocarbon chain.
Non-essential (we can make them if not in diet) |
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What is an unsaturated fatty acid?
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Has double bond(s) in the hydrocarbon chain.
There are two types: - monounsaturated - polyunsaturated |
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WHat is a monounsaturated fatty acid?
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Has ONE double bond in hydrocarbon chain.
Non-essential |
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What is a polyunsaturated fatty acid?
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Has two or more C=C double bonds, 3 C-atoms apart.
Some are essential in the diet. |
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What are the essential fatty acids?
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Those with w3 and w6 double bonds must be supplied in the diet. i.e. omega-3 fatty acids & omega-6 fatty acids.
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What are omega-3 fatty acids required for?
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- The development of nervous system & retina
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What are omega-6 fatty acids required for?
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- They are a key component in the phospholipid membrane.
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What are cis fatty acids?
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Those with the hydrogens (acyl chain) on the same side of the bond.
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What are trans fatty acids?
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Those with one hydrogen on each side of bonds. Acyl chains on opposite sides of the bond.
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Are most unsaturated long chain fatty acids cis or trans?
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Cis
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What do trans bonds do?
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They change the fatty acid from an L shape to being straight. They act more like saturated FA.
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What properties are associated with trans-unsaturated fatty acids and saturated fatty acids?
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- Straight, rigid shape.
- Decreased membrane fluidity - Increased cholesterol levels & therefore risk of cardiovascular disease |
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What are the functions of cis-unsaturated fatty acids?
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- Cell membrane function
- Neural development - Cholesterol metabolism - Immune and inflammatory response |
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Where in the diet are saturated fats?
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- Meat
- Dairy - Butter - Oils (palm, coconut, palm kernel) |
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Where in the diet are monosaturated fats?
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- Nuts
- Olives - Meat products - Oils (olive, grapeseed, macadamia nut, sesame) |
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Where in the diet are polyunsaturated fats?
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- w-3: fish, green leafy vegetables, flaxseeds, walnuts and soybeans
- w-6: vegetable oils, flaxseed, walnuts & soybeans |
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How are fatty acids stored?
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As triglycerides.
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How many kJ per gram of triglycerides?
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37kJ (9 cal)
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How are triglycerides formed?
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3 fatty acids + 1 glycerol
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Where are triglycerides stored?
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Adipocytes in adipose tissue :)
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Can triglycerides be made/stored from non-FA precursors?
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YES. Can be made from glucose and amino acids.
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Where are triglycerides mainly used as an energy source?
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By the liver, heart & skeletal muscle.
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What is the structure of cholesterol?
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4 aromatic rings with a short hydrocarbon tail.
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What are the main functions of cholesterol?
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- Component of plasma membrane
- Component of bile - Production of steroid hormone & vitamin D production |
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Where is cholesterol found in the diet?
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- Cheese
- Egg yolk - Meat - Shell fish |
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Is cholesterol essential in the diet?
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NO.
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Where is cholesterol produced?
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Mainly in the liver & then transported to cells by lipoproteins.
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What are phospholipids composed of?
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Glycerol + 2 fatty acids + phosphate group (linked to small hydrophilic compound)
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Phospholipids are amphipathic... meaning ?
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They are lipid-loving AND water-loving
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Functions of lipids re cell membranes?
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- Maintain membrane integrity
- Determine which substances move in/out of cell - Regulate which substances can bind to cell |
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What are eicosanoids?
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- 'Local' hormones
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What are the functions of eicosanoids?
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- Blood clotting
- Immune system & inflammatory response - Blood pressure |
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How are eicosanoids made?
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A 20-C polyunsaturated FA cleaved from cell membrane.
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How are lipids transported in the body?
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- Fatty acids (from adipose tissue) bound to albumin (plasma protein)
- As lipoproteins |
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What are lipoproteins?
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It is a lipid-protein complex that allows fat to move through water inside & outside cells.
Cholesterol, triglycerides, phospholipids are wrapped in protein & hydrophilic 'shell' makes it soluble. |
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How are they transported around body?
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1. Chylomicrons formed in enterocytes of SI
2. Delivered to body cells for various uses 3. Chylomicron remnant circulates to liver |
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How does the liver process the lipids?
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Remember: the liver does not store fat.
It packages lipids into lipoproteins called VLDL or LDLs. |
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What are VLDLs?
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They are lipoproteins containing large amounts of triglyceride. VLDL delivers TG to various body cells or adipose tissue for storage.
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What are LDLs?
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LDLs are lipoproteins containing large amounts of cholesterol. LDLs transport cholesterol to body cells. Body cells contain receptors for LDLs and internalise it upon binding.
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What are HDLs?
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They are lipoproteins containing large amounts of protein. They're often referred to as 'good cholesterol'. They bind to plasma cholesterol and transport it to the liver - called 'reverse cholesterol transport'.
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What percentage of our energy intake should come from fat?
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20-35% -- mono:poly:sat
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