Chapter 6 - Lipids

Question 1

Triglycerides

Answer 1

• the main dietary lipid
• have glycerol backbone with three fatty acids

Question 2

What are the degree of saturated fatty acids

Answer 2

Saturated = no double bonds
Unsaturated - one (mono) or more (poly) double bonds

Question 3

What is an example of a polyunsaturated fatty acid

Answer 3

Omega-3 is an example of a polyunsaturated fatty acid. It is named by the position of the double bond from the end of the chain

Question 4

What are essential fatty acids

Answer 4

Omega 3 - alpha-linoeic acid and Omega 6- linoeic acid. They can be used to form eicosanoids (hormone like molecules)

Question 5

Describe the relative length of fatty acids and where they would be found

Answer 5

Long chain fatty acids: found in a variety of animal products (14+ carbons)
Medium chain fatty acids: found in tropical oils (6-12 carbons)
Short chain fatty acids are made by bacteria when they ferment indigestible carbs (2-4 carbons)

Question 6

What is hydrogenation

Answer 6

The artificial production of trans fatty acids

Question 7

What are sterols

Answer 7

Have a hydrocarbon chain arranged in a ring formation
- can be found in both animal and plant products

Question 8

Animal derived sterols

Answer 8

• Cholesterol
• Main roles include: cell membrane structure, precursor for vitamin D, precursor for estrogen and testosterone
• Can be synthesized by the liver so is not essential from diet

Question 9

Plant derived sterols

Answer 9

• Phytosterols
• found in unrefined vegetable oils, buts, seeds, fruits
• may limit absorption of animal sterols

Question 10

Functions of phospholipids

Answer 10

• Form bilayer
• act as emulsifiers
• carry other lipids around body

Question 11

Describe lipid digestion

Answer 11

Begins in mouth with the secretion of lingual lipase, which will chemical digest medium and short chain fatty acids, mechanical digestion also separates lipids in the mouth. In the stomach gastric lipase is secreted to digest medium and short chain fatty acids. In the small intestine bile will be secreted by the liver and pancreatic lipase will be secreted by the pancreas to digest the remaining lipids

Question 12

Describe lipid absorption

Answer 12

Micelle breaks down and the lipid content is absorped into the small intestine cells through passive diffusion.
Lipids get wrapped in phospholipids as they exit the small intestine cell and enter the centre of the villus creating a chylomicron. The chylomicron will then enter the lacteals

Question 13

What are the different types of lipoproteins

Answer 13

Chylomicron, VLDL, LDL, and HDL

Question 14

Describe the transport of chylomicron

Answer 14

Delivers triglycerides from the small intestine villus –> lymph –> blood –> body cells –> liver

Question 15

Describe the transport of VLDL

Answer 15

Delivers triglycerides. Made in liver –> body cells –> becomes LDL as it looses triglycerides

Question 16

Describe the transport of LDL

Answer 16

Delivers cholesterol. From VLDL –> delivers cholesterol to body cells, returns to the liver, or get deposited into artery walls

Question 17

Describe the transport of HDL

Answer 17

Mainly removes cholesterol from blood and body cells. Made in liver –> picks up cholesterol from blood cells –> returns it to liver

Question 18

What are the lipid functions

Answer 18

• Energy provision
• membranes
• transport and storage of fat soluble vitamins
• Synthesis of other key molecules

Question 19

Describe the function of lipids in energy provision

Answer 19

Lipids provide 9 kcal/g of energy. If carbohydrates are inadequate in the diet, triglycerides are metabolized and their products enter the citric acid cycle

Question 20

Describe the function of lipids in transport and storage of fat soluble vitamins

Answer 20

Vitamines A, D, E and K are fat soluble vitamins and since they are hydrophobic, they require lipoproteins for transport. They can also be stored in adipose tissue

Question 21

Describe the function of lipids in the synthesis of other molecules

Answer 21

Cholesterol-derived molecules include: steroid hormones, bile salts, vitamin D, estrogen and testosterone
Essential fatty acid-derived molecules include: eicosanoids, and endocannabinoids

Question 22

What is atherosclerosis

Answer 22

the build up of fatty materials in artery walls. A type of CVD that causes heart attacks and some strokes

Question 23

Trans fatty acids and their link with CVD

Answer 23

Known to increase
- Ratio of LDL to HDL
- Risk of CVD
- Risk of CVD morality

Question 24

Saturated fatty acids and health

Answer 24

Diets high in Saturated fats increase LDL which increases risk of CVD

Question 25

Omega 3 and health

Answer 25

have several cardioprotective effects including decreasing inflammation, blood cholesterol, vasoconstriction, and blood clotting

Question 26

Omega 6 and health

Answer 26

Though to increase risk of CVD because the increase inflammation and blood clotting

Question 27

What are the effects of omega 3 and 6 on the brain

Answer 27

Both omega 3 and 6 are being studied for potential to improve brain health, and reduce risk of alzheimers

Question 28

What are cholesterol hyper-responders

Answer 28

25-30% of people, their LDL goes up when more cholesterol is consumed. In most people there is no increase in LDL when cholesterol intake is increased

Question 29

Plant sterols and health

Answer 29

Reduce LDL by competing with cholesterol for absorption and altering cholesterol metabolism