Revision questions - week 5

Question 1

What are the types of lipids found in food

Answer 1

o	Triglyceridesn
o	Phospholipids
o	Cholesterol
o	Free fatty acids
o	phyrosterols

Question 2

lipids kj amount

Answer 2

37kj per 1g

20-35% EER

Question 3

triglycerides formation and breakdown

Answer 3

Esterification
De-esterification
Re-esterification

Question 4

Esterification

Answer 4

joining 3 fatty acids to a glycerol unit

Question 5

De-esterification

Answer 5

lipolysis of adipose tissue stores: releases FA from glycerol: resulting in FFA

Question 6

Re-esterification

Answer 6

reattaching FA to glycerol (absorption)

Question 7

How are trans-fats found in foods produced?

Answer 7

• Through partial hydrogenation of polyunsaturated fatty acids (adding a hydrogen to the double bond in fat)
• Will extend shelf life

Question 8

Describe the digestion, absorption and transport of dietary lipids

Answer 8

mouth - lingual lipase
stomach - gastric lipase
small intestine
- CCK triggers bile->converts to micelles + FFA
- pancreatic lipase ->broken down to monoglycerides and FFA
- phospholipase A2 -> phospholipids broken down to FFA, glycerol and phosphoric acid
- cholesterol esterose -> cholesterol esters broken down to cholesterol and FFAs (lymphatic system)
enterohepatic circulation, esterification of long chains, bind to albumin and taken to liver SC and MC

Question 9

characteristics, composition and role of the four main lipoproteins

Answer 9

1. Chylomicrons: composed of apolipoprotein, phospholipids and free cholesterol, transport fat through the lymhatic system
   2 VLDL: triglycerides - carries lipids from liver to cells
2. LDL: cholesterol from liver to cells
3. HDL: cholesterol from cells to liver

Question 10

What are the chemical characteristics and specific physiological function of dietary fatty acids?

Answer 10

??

Question 11

How do omega 3 polyunsaturated fats increase circulating HDL

Answer 11

Promotes gene expression of APOA1 which increase HDL

Question 12

rich food source - long chain

Answer 12

12+ carbons

-beef, pork, lamb and most plant oils

Question 13

rich food source - medium chain

Answer 13

6-11 carbons

- coconut and palm kernel oil (Sat fat)

Question 14

rich food source - short chain

Answer 14

less than 6 carbons

-butter

Question 15

rich food source - saturated fat

Answer 15

coconut oil and palm kernel oil

Question 16

rich food source - monounsaturated

Answer 16

olive oil and avocado

Question 17

rich food source - polyunsaturated

Answer 17

fish - EPA and DHA , flax seed (plants) N-3 ALA – precursor of EPA and GHA

Question 18

What are EFAs?

Answer 18

essentail fatty acids

Question 19

Why are EFA’s essential?

Answer 19

Essential as humans can not make them

Question 20

What are the precursors of EFAs? eicosanoids

Answer 20

• Omega 6 precursor – linoleic acid e.g. vegetable and sunflower oils (LA, GLA, AA)
• Omega 3 precursor – alpha linoleic acid e.g. green leafy veges (ALA, SDA, ETA, EPA)

Question 21

Omega naming system

Answer 21

first number is carbons, next number is how many double bonds, N-? is where the first double bond is from omega end

Question 22

Delta naming system

Answer 22

first number is amount of carbons, second number is how many double bonds, subscript number is how many carbons along from the delta end the first double bond is

Question 23

Functions of EFA’s

Answer 23

Important structural components of cell membranes:

DHA and EPA

Question 24

Eicosanoids

Answer 24

• Signaling molecules
• Made by enzymatic or non-enzymatic oxidation of arachnoid acid or other similar PUFAs (those with 20 carbon units in length)

Question 25

DHA and EPA

Answer 25

- Keep membranes fluid and flexible - DHA: Needed during fetal life and infancy for: - Normal development and function of retina - Normal development and maturation of nervous system - Needed throughout life for: - Regulation of nerve transmission and communication - Important signaling for gene expression

Question 26

What are the 5 enzymes involved in the digestion of lipids?

Answer 26

``` o Lingual lipase o Gastric lipase o Pancreatic lipase o Phospholipase A2 o Cholesterol lipase ```

Question 27

What is the enterohepatic circulation

Answer 27

It is the recycling of bile by absorption of 95% of bile salts

Question 28

What is the purpose of enterohepatic circulation

Answer 28

recycling of bile | can help to promote reduction of serum cholesterol

Question 29

sources of circulating cholesterol?

Answer 29

- Endogenous (80%) synthesis – production of cholesterol with acetyl coA as starting molecule (in liver, intestines, adrenal glands and gonads). - diet (20%) e.g. eggs, meat, seafood

Question 30

endogenous synthesis

Answer 30

* High glucose levels stimulates cholesterol synthesis * high insulin levels promotes endogenous synthesis * high levels of circulating cholesterol inhibit endogenous synthesis

Question 31

What is measured when blood cholesterol blood is measured?

Answer 31

lipoproteins

Question 32

Apolipoprotein

Answer 32

proteins that bind lipids to form lipoproteins

Question 33

What is cholesterol uptake in the cell

Answer 33

Receptor pathway | Scavenger pathway

Question 34

Receptor pathway

Answer 34

- LDL are up-taken, broken down and utilized by cells | - Excess not taken up may become oxidized in the blood

Question 35

Scavenger pathway

Answer 35

Removes oxidized LDL the can burrow under endothelium (if left can build up and burrow underneath the endothelium forming plaque which can narrow the blood vessel lumen)

Question 36

What are plant sterols?

Answer 36

Plant sterols are similar to dietary cholesterol but cant be converted to steroids in body - reducing absorption of dietary cholesterol as it competes with it at the receptor

Question 37

How can plant sterols reduce dietary cholesterol absorption?

Answer 37

Can reduce cholesterol absorption as have the ability to bind to the same receptors and compete for absorption therefore can be absorbed instead of cholesterol

Question 38

How can oats reduce circulating cholesterol?

Answer 38

Oats help lower cholesterol re-absorption by promoting excretion of bile

Question 39

MCT metabolism

Answer 39

are more readily utilised for energy production, higher ketone body production, produce acetyl coA faster - short chains are absorbed directly into the BS via portal vein

Question 40

LCT metabolism

Answer 40

re-esterification and combine to cholesterol and protein to form chylomicrons - travel via lymphatic system

Question 41

the role of EFA’s in the inflammatory response

Answer 41

- Omega 3 – pro anti-inflammatory | - Omega 6 – pro inflammatory

Question 42

Briefly, how does atherosclerosis develop? How is dietary fat involved in this process?

Answer 42

- Associated with high blood cholesterol as if high cholesterol LDL receptor synthesis is blocked -> LDL build up in blood ->LDL taken up by macrophages becoming foam cells ->foam cells trapped in wall of blood vessel ->contribute to atherosclerotic plaque formation - Results • Hardening of the arterial wall -> hypertension • Heart attack and strokes risk due to blockage in blood vessels that stops blood flow to the heart or the brain

Question 43

What are the Australian dietary guidelines for fat intake for the general healthy adult population?

Answer 43

20-35% in which <10% is sat and trans

Question 44

nutritional characteristics of the TMD

Answer 44

- 40-45% carb - 15% protein - 40-47% fats much higher fruit, vege and fat content than normal diets

Question 45

Diet-heart hypothesis

Answer 45

That high level of cholesterol in the blood is a significant causative factor in atherogenesis and its clinical expression

Question 46

What did the PREDIMED study demonstrate?

Answer 46

demonstrated that a high unsaturated fat and antioxidant-rich dietary pattern such as MeDiet is a useful tool in the prevention of CVD