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Nutrition > Chapter 6 - Lipids > Flashcards

Chapter 6 - Lipids Flashcards

1
Q

Structure of Triglycerides

A
  • Consist of 3 fatty acid tails bonded to the hydroxyl groups on glycerol head
    • Process of bonding is called esterification as water is released to create the ester bond
    • Structure of fatty acids is composed of a long chain of carbon atoms surrounded by hydrogen atoms
    • Free fatty acids have a carboxyl group and a methyl group at each end
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2
Q

De Esterification and Re-esterification

A

○ De-esterification: removing a fatty acid
○ Re-esterification: reattaching a fatty acid

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3
Q

Ways Fatty Acids Can Vary

A
  • Number of carbons in the chain
  • The extent to which the chain is saturated with Hydrogen
  • Shape of the chain(bent or straight)
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4
Q

Number of Carbons in different Length Chains:

A
  • Long chain fatty acids: at least 12 carbons
  • Medium chain fatty acids: 6-10 carbons
  • Short chain fatty acids less than 6 carbons
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5
Q

Saturation Differences

A
  • Saturated: every carbon in the chain has formed a maximum of 4 bonds(2 to carbons and 2 to hydrogens)
    ○ Animal products
    ○ Can stack together neatly and form a solid mass
    • Unsaturated: Plant products which cant uniformly stack together and therefore remain liquidy
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6
Q

Types of Unsaturated Chains

A

○ monounsaturated: a single double bond between carbon atoms due to the absence of hydrogen atoms

○ Polyunsaturated: 2 or more double bonds in the carbon chain due to the absence of hydrogen atoms at different locations

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7
Q

Variation in Chain Shape due to bonding patterns of Hydrogens

A
  • Cis fatty acids: the hydrogens attached to the double bonded carbons on the same side
    ○ How its found naturally
  • Trans fatty acids: the hydrogens attached to the double bonded carbons zigzag back and forth across the carbon chain
    ○ Partially hydrogenated made in labs making it stack like saturated fat in our arteries
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8
Q

Systems used to Name Fatty Acids

A

Omega system: indicates where the first double bond closest to the methyl(omega) end of the chain occurs
- E.g. Linoleic acid is 18:2 omega6, meaning it has 18 carbons, with 2 double bonds and the first double bond starts at the 6th carbon from the omega end

Delta system: indicates where the first double bond closest to the carboxyl(delta) end of the chain is

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9
Q

2 essential fatty acids

A
  • Human body cannot create alpha linolenic acid and linoleic acid
    • Therefore they are essential fatty acids which must be supplied through diet
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10
Q

Determining Fatty Acid Family

A
  • Location of double bond closest to the omega end determines the fatty acids family
  • E.g. 1st double bond occurs between the 3rd and 4th carbon, it is an omega-3 fatty acid
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11
Q

Sources of Triglycerides

A
  • Saturated Fats: animal products
  • long chain: fat in beef, pork, lamb
  • med/short chain: milk fat, butter
  • Unsaturated fats: plant products
  • mono: olive oil, canola oil, peanut oil
  • poly: sunflower oil, corn oil, fish oil
  • omega 3 Eicosapentaenoic acid: tuna, salmon
  • Omega 3: alpha-linolenic acid: walnuts, chia seeds
  • omega 6 linoleic acid: beef, chicken eggs
  • natural trans fatty acid: milk, meat
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12
Q

Functions of Triglycerides: energy providing

A
  • Provide 9 calories per gram
    • Main fuel source for all body cells except the nervous system and red blood cells
      • Provide up to 70% of energy during rest or light PA
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13
Q

Function of Triglycerides: energy storage

A
  • Excess calories from other macronutrients are converted into fatty acids and then to triglycerides
    • Triglycerides can be easily stored due to how stable they are and because they can expand 2-3 times their size
      ○ Adipose cell can increase in weight about 50 times
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14
Q

Function of Triglycerides: insulation and protection

A
  • Insulating layer of fat under the skin, subcutaneous fat is made of triglycerides
    • Visceral fat surrounds organs protecting them
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15
Q

Functions of Triglycerides: Aid fat soluble vitamin absorption and transport

A
  • Fats in food carry Fat soluble vitamins(ADEK) to the small intestine where dietary fats assist in their absorption
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16
Q

Functions of Essential Fatty Acids

A
  • Eicosanoids have heaps of actions including regulation of:
    ○ BP
    ○ Blood clotting
    ○ Sleep wake cycles
    ○ Body temperature
    ○ Inflammation
    ○ Hypersensitivity
17
Q

Function of Phospholipids

A

Emulsifier: a compound which forms a shell around fat droplets so that the droplets can be suspending in water and not clump together
- E.g. bile and lecithins
- Hydrophobic tails reach towards fat droplets, forming the inside of the shell
- the hydrophilic heads extending away from the fat droplet, allowing it to mix with water
- Important for fat to be digested and transported through the bloodstream

18
Q

Sources of Phospholipids

A
  • Can be either synthesized by the body or supplied through diet
    • Lecithins can be found in foods such as:
      ○ Egg yolks
      ○ Wheat germ
      ○ peanuts
19
Q

Functions of Sterols

A

Cholesterol:
- Makes sex hormones
- Makes the active form of vitamin D
- Makes adrenal hormones like cortisone
- Makes bile, an emulsifier

- Part of the cell membrane allowing fat soluble substances to move in and out
20
Q

Food Sources of Sterol

A
  • Foods of animal origin
    ○ Meat
    ○ Fish
    ○ Poultry
    ○ Eggs
    ○ Dairy
    • 1/3 of cholesterol comes from food while 2/3 is produced by the body
21
Q

Fat Digestion

A
  • Begins in the mouth where lingual lipase is secreted from the base of the tongue, breaking down triglycerides with short and medium chain fatty acids
    • In the stomach gastric lipase breaks down triglycerides into mono, di and free fatty acids
      ○ Lipid digestion is limited due to it floating on top of the water contents in the stomach
    • Fat in the small intestine then triggers the release of CCK which stimulates the release of bile, lipase and colipase
      ○ Bile emulsifies fat and breaks it into many tiny droplets and forms shells around it
      ○ Increases the surface area of fat and allows pancreatic lipase to break it down into free fatty acids
    • Phospholipids and cholesterol are also digested in the small intestine by phospholipase and cholesterol esterase
22
Q

Fat Absorption

A
  • Lipid portion of micelles is absorbed by brush border of absorptive cells in the Duodenum and Jejunum
    • Short and medium chain fatty acids enter the cardiovascular system
    • Long chain fatty acids are re-esterified into triglycerides in the absorptive cell before entering the lymphatic circulation
    • Bile is re-absorbed and re secreted through enterohepatic circulation
23
Q

Micelles

A

water soluble structures formed by emulsifiers surrounding fat droplets

24
Q

Recommended Fat Intakes

A
  • AMDR is between 20-35% of calories
  • less than 10% saturated fat of fat intake

Nutrition (6 decks)

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