Nutrition lecture 5 - Lipids

  1. Lipids are soluble in?
    Organic solvents such as ether, chloroform etc etc
  2. What atoms do lipids contain? In what proportion to carbs? relate this to energy
    • C H O
    • More C and H in proportion to O when compared to carbs
    • As a result they have roughly 2.25x more energy than carbs and proteins
  3. are lipids found at high levels in plants?
    No relatively low in plants as they store energy as carbs
  4. Do we find high lipid levels comparatively in animals? What does it vary with? (2 that just make sense)
    • Yes as compared to carbs
    • Age, sex, nutrition
  5. 8 components of lipids? Where can we find this in proximate analysis?
    • Fats and oils (triglycerides)
    • Waxes
    • Phospholipids
    • Glycolipids
    • Lipoproteins
    • Steroids
    • Terpenes
    • Fat soluble vitamins

    Ether extract
  6. What determines fats vs oils?What are fats vs oils?
    • Chain length - (long = fat)
    • Degree of saturation (saturated = fat)
    • Fat = solid at room temperature
    • Oil = liquid at room temperature
  7. What are the most important lipid class? What are they made of?
    • Fats and oils (triglycerides)
    • Glycerol and 3 FFA
  8. What are the 2 ends of fatty acid molecule?
    • Methyl end
    • Carboxyl end
  9. Name 5 common saturated fatty acids?
    • Acetic acid
    • Butyric acid
    • Myristic acid
    • Palmitic acid
    • Stearic acid
  10. Define a short chain, medium chain and long chain fatty acid
    • Short = less than 6 carbons
    • Medium = 6-12 carbons
    • Long = 14 carbons or more
  11. Unsaturated by definition essentially means what?
    • Every carbon in the chain is not bound to atleast 2 H
    • Contains double bonds
  12. Unsaturated fatty acids can occur in what 2 configurations
    Cis and trans
  13. 3 levels of saturation of fatty acid chains?
    • Saturated
    • Monounsaturated
    • Polyunsaturated
  14. Name 4 important unsaturated fatty acids?
    • Oleic
    • Linoleic
    • Linolenic
    • arachadonic
  15. What is meant when it is said that the position fo the fatty acid on the triglyceride is important?
    FA on the midd or 2 position is harder to digest than those in the alpha 1 or 3 positions
  16. 3 factors affecting fatty acid digestibility?
    • Position of the FA on the triglyceride
    • Chain length
    • Degree of saturation
  17. Are most fats and oils highly digestible?
  18. Explain the general rules with chain length and level of saturation on digestibility?
    • Longer chains are less digestible
    • More saturated FA are more digestible
  19. Do most common feedstuffs such as protein supplements and cereal grains have high fats? Where do we get it from?
    • NO around 1-3%
    • Rendering, off grade vege oils, etc etc
  20. Give 10 good reasons why we add lipid to livestock feed?
    • Energy
    • Palatability
    • Fat soluble vitamins
    • Lubrication
    • Essentially FA
    • Alleviate heat stress
    • dust control
    • lubrication of equipment
    • provide pigment
    • reduce mortality
    • improved diet handling
  21. Lipid contains how much more energy than a typical carb? How can this be useful?
    • 2.25
    • Very good for increasing energy/caloric density of a diet
  22. What are the fat soluble vitamins?
  23. How does fat in the diet increase absorbtion of fat soluble vitamins?
    Helping absorbtion and vitamin stability
  24. What are the 3 essential FA? Give 5 functions fo the FA
    • Linoleic
    • Linolenic
    • Arachadonic

    • Lipid transport
    • Connective tissue formation
    • Cell membrane component
    • Enzyme system component
    • Prostaglandin component
  25. Give 3 good symptoms of essential FA deficiency?
    • Kidney lesion
    • Cessation of growth
    • reproductive failure
  26. Why does a lipid ration alleviate heat stress in animals and why is this a good thing?
    • Because breaking bonds of compounds and with lipid digestion and metabolism there is less bond breaking
    • Good because more energy going to heat is more energy wasted
  27. Explain how lipids can improve air quality?>
    MOst barn dust is from feed, if this feed has a lipid added it can seriously benefit the dust amount in the air (ex. 5% tallow reduced air dust by 50%)
  28. What is meant when it is said that lipid improves diet habndling?
    • Makes a better quality pellet, fewer fines and less crumbling
    • We dont want fines cause they are unpalatable
  29. Why does lipid increase pigments in food?
    Helps carry carotenoids
  30. Give 3 ways that fat supplementation to the diet of a sow can help the survival rate of pigs?
    • Increase pig body stores
    • increase sow milk production
    • Increase sow milk fat

    reduced pre weaning mortality
  31. What are 2 lesser known maybe not so main stream uses for lipid on animals?
    • Laxative
    • improvement on hair coat
  32. What are the 2 forms of rancidicty? Explain each
    • Hydrolytic - Cleavage of ester bond between glycerol and FFA by naturally occuring lipase get release of short chain FA
    • Oxidative rancidity - Oxygen reacting with unsaturated FA to produce aldehydes and ketones
  33. Why can we taste rancidity so intensley?
    Because we taste individual Fatty acids more than total triglycerides and short chain FA such as butyric acid are particularly well perceived by the tongue
  34. When a FA goes through rancitidity does it lose its essential fatty acid activity
  35. In ocidative rancidity what bond gets attacked?
    Double bond
  36. Oxidative rancidity is accelerated by? Such as? And prevented by? Such as?
    • Pro oxidants
    • UV light, heat, moisture, etc
    • Anti oxidants 
    • Vitamin E, ethoxyquin etc
  37. Is most lipid added to the feed deliberately or is it just occuring with other ingredients?
    Added deliberately
  38. What form is the lipid in most diets present in? (majority) What about the minority of it?
    • Triglycerides or neutral fats
    • Cholesterol, phospholipids, cholesterol esters etc
  39. Principle site of lipid digestion?
    Small intestine
  40. Why no lipid digestion in the stomach?
    To acidic for lipid digesting enzymes
  41. What is a common problem associated only with lipid digestion?
    • Digestive enzymes are proteins thus water soluble.... dont have good access to their substrate
    • Need to tools to bring them in contatc
  42. 3 MAJOR hormones of lipid digestion?
    • Secretin
    • Pancreozymin
    • Cholecystokinin
  43. What does secretin and pancreozymin do? Where are they released from? What about cholecystokinin?
    • stimulate release of digestive enzymes from the pancreas
    • Duodenum
    • Induces contraction and emptying of the gallbladder
  44. Bile is made? Consists of? Is stored in the? And is reabsorbed where?
    • IN the liver
    • Cholesterol bile acids and bilirubin
    • gallbladder
    • ileum
  45. Describe the gallbladder?
    • Muscular sac
    • Stores and concentrates bile
    • Located on caudal aspec of liver
  46. How does  lipid normally exist with no emulsion tools? What is the first step in changing this? How is this done? What is the process called?
    • Coarse emulsion with large fat gobules
    • Breakdown into smaller globules so that water soluble enzymes have more SA access
    • Bile lowers the surface tension of lipid gobules the globules are broken up by the churning intestine
    • Emulsification
  47. Are hormones considered tools in the breakdown of lipids?
    No they help us get our tools
  48. How does emulsification help us break down fat? What does extensive emulsification with bile eventually result in? Is this chemical digestion?
    • Gives access to more SA
    • Small water soluble fat globules covered in bile salts
    • No, no chemical bonds are actually broken
  49. What are the 3 main enzymes for lipid digestion? What causes excretion of these enzymes? From where?
    • Pancreatic lipase (most important)
    • Cholesterol esterase
    • Phospholipase

    • Response to hormones pancreozymin and secretion
    • All secreted from the pancreas
  50. Which lipid digesting enzyme breaks down triglycerides?
    Pancreatic lipase
  51. Which positions on a triglyceride are the most susceptible to breakdown?
    1 &3 (edges)
  52. Pancreatic lipase breaks down? Prefers what positions to produce what?
    • Triglycerides
    • 1 & 3 creates often 2 FFA and one monoglyceride or 3 FFA and a glycerol
  53. While we do talk about the cholesterol digestion is it common compared to triglycerides?
    Triglycerides are 100X more common
  54. What hormone breaks down cholesterol? Breaks it down to what? Can we directly absorb cholesterols?
    • Cholesterol esterase
    • FFA
    • Yes only in free state
  55. What enzyme breaks down phospholipids? Hydrolyzes what from the phospholipids? Is most phospholipid digested
    • Phospholipase
    • FFA
    • No most is used in the formation of chylomicrons or micelles
  56. What are the 5 most common products of lipid digestion?
    • GLycerol
    • FFA
    • Monoglycerides
    • Free cholesterol
    • Phsphoric acid
  57. Does the lipid solubility of the digested products from lipid digestion still pose a problem?
    Yes they cannot be transported easily
  58. What types of fatty acids dont need help to be absorbed? Why? How are the other types  absorbed?
    • Short chain FA less than C-10
    • Soluble in water
    • Through the use of micelles which are loose affiliations of bile acids and lipids
  59. What do the bile acids do in the micelle formation?
    Protect lipids from the water
  60. What makes bile acids unique?
    • Amphipathic
    • Polar end and non polar end
  61. Name 4 bile acids?
    • Cholic acid
    • Deoxycholic acid
    • Taurocholic acid
    • Glycocholic acid
  62. Describe the micelles in terms of structure and size
    • Small spherical globules of 20-50 molecules of bile salt
    • Bile salts form a ring around FA and monoglycerides allowing transport in water
  63. What happens once the micelle is formed?
    • Migrates to the brush border of epi cells where it is disrupted
    • Lipid portion absorbed bile portion is recylced and continues to work in intestine
  64. Where is bile often reabsorbed in the body?
  65. For these common saturated FA give the chain length
    • 2
    • 4
    • 14
    • 16
    • 18
  66. For these important unsaturated FA give the chain length and the # of double bonds
    • 18.1
    • 18.2
    • 18.3
    • 20.4
  67. What happens to all the lipid giestion products once they are absorbed into the cells?
    Reformed into triglycerides along with cholesterol and phospholipids are given a protein coat called a chylomicron
  68. Chemically what is a chylomicron?
  69. Describe the layers of a chylomicron?
    • cholesterol triglyceride core
    • Phosphlipid layer
    • Then apoprotein on outside
  70. Chylomicrons are too big to be absorbed into the blood directly, where do they go?
    Released into lymphatic vessels and travel to thoracic duct where they are released into general circulation
  71. Clearance of chylomicrons takes about?
    2-10 hours
  72. if insufficient carbs are not present for fat breakdown what happens?
    Ketones are produced
  73. Why are carbs necessary for the TCA cycle and therefore approrpiate fat breakdown?
    Need them to form intermediates
Card Set
Nutrition lecture 5 - Lipids
Nutrition lecture 5 - Lipids