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NUTR2101 > Week 5 > Flashcards

Week 5 Flashcards

1
Q

Lipids are a diverse group of organic substances commonly associated on the basis of:

A

Insolubility in water

Solubility in fat solvents (e.g. ether/chloroform)

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2
Q

What are the most common form of lipids in food and the body

A

Triglycerides

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3
Q

What are 5 dietary lipids?

A
  • triglycerides
  • Phospholipids
  • Cholesterol
  • Phytosterols
  • Free fatty acids
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4
Q

What is esterification?

A

The joining of 3 fatty acids to a glycerol unit

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5
Q

De-esterification

A

removal of fatty acids from a glycerol, resulting in fatty acids

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6
Q

What are the lengths of carbon chains that make long, medidium and short chain fatty acids?

A

long: 12 or more
medium: 6 to 11
short: less then 6

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7
Q

What are some good sources of omega 3 fatty acids?

A

fish, shellfish, flax seed, soy bean, walnuts

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8
Q

what are some good sources of omega 6 fatty acids?

A

corn oil, sunflower oil, safflower oil

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9
Q

what are some good courses of omega 9 fatty acids?

A

avocado, olive oil, peanuts, almonds

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10
Q

Define saturated, monounsaturated, polyunsaturated and trans fatty acids

A

saturated: all c-c bonds are single bonds only
monounsaturated: one single double bond
polyunsaturated: 2 or more double bonds
trans: Partial hydrogenation of polyunsaturated fatty acids in food processing methods or also naturally occurring in ruminant-derived foods

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11
Q

how are trans fatty acids formed?

A

by adding a hydrogen to make unsaturated fatty acids more saturated yield trans fatty acids (hydrogenation)

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12
Q

what are the 2 systems for naming polyunsaturated fatty acids?

A 
1. omega 
The number (n-3, n-6) refers to the position of the first
double bond closest to omega (methyl) end.
2. delta 
Uses the carboxyl end for the first double bond, and
also indicates the location for all double bonds
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13
Q

What are essential fatty acids?

A

fatty acids thats must be consumed in the diet as the body cannot make them. lack of Δ12 and Δ15 desaturase enzymes that incorporate double bonds at specific positions.

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14
Q

What are some essential fatty acids?

A
  • Linoleic acid (18:2 n-6)
  • Υ-linolenic acid (18:3n-6)
  • Arachidonic acid (20:4 n-6)
  • αlpha-linolenic (18:3 n-3)
  • Omega 3 fatty acids
  • Eicosapentaenoic acid(EPA) (20:5 n-3)
  • Docosahexaenoicacid (DHA) (20:6 n-3)
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15
Q

How much energy does fat provide?

A

37 KJ/g

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16
Q

What are some functions of fat in the body?

A

provides energy
insulates and protects the body
Cell membrane strength (saturated fat and cholesterol) and
fluidity (PUFA)
Assists in fat soluble vitamins absorption and transport

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17
Q

What are the functions and sources of phospholipids?

A

function:
components of cell membranes to protect cytosol and movement of compounds in and out of the cells
emulsifier

sources synthesized in the body
food: egg yolk, wheat germ, lecithin and peanuts

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18
Q

What are the functions and sources of sterols?

A

Function:
cholesterol is a precursor of sex and adrenal hormones (steroids), vitamin D, bile salts; involved in cell membrane stability; part of lipoproteins.

sources:
Endogenous synthesis: in the liver, adrenal glands, intestines and gonads
Dietary: food of animal origin (egg, dairy, poultry, fish, meat)

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19
Q

What are sterols also called?

A

cholesterol

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20
Q

What are the functions of essential fatty acids?

A

important sturctural components of cell membranes (DHA, EPA)
keeps membrane fluid and flexible

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21
Q

When is the essential fatty acid DHA needed and why?

A

Needed during fetal life and infancy for:
• Normal development and function of the retina
• Normal development and maturation of the nervous system

Needed throughout life for:
• Regulation of nerve transmission and communication
•Important signaling for gene expression

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22
Q

What are EFA’s precursors for?

A

EFAs are precursors of eicosanoids, hormone like molecules

23
Q

What are the functions of Eicosanoids?

A

Produced from omega-6:

  • Influence blood vessels to constrict and raise blood pressure
  • Promote pro-inflammatory response via prostaglandins and thromboxanes series 2

Produced from omega-3

  • Dilate blood vessels and decrease blood pressure
  • Promote anti-inflammatory response via prostaglandins and thromboxanes series 3
24
Q

What are some good sources of omega 3?

A 
Sardines 
Salmon 
Halibut 
Shrimp
Cod
Tuna
“Omega 3 eggs” (hens’ feed is fortified)
Flax seeds and walnuts (precursor ALA only)
Fortified product
25
Q

What are some good sources of omega 6?

A

Vegetable oils (corn, sunflower, safflower, soy)
Nuts
Whole wheat bread
Chicken

26
Q

What is the role of bile in the small intestine?

A

emulsifies fat to convert into smaller droplets (micelles) with larger surface area.

27
Q

What is the role of pancreatic lipase?

A

Triglycerides in micelles are broken down into monoglycerides and free fatty acids

28
Q

Phospholipids are broken down into free fatty acids, glycerol and phosphoric acid by…

A

phospholipase A2

29
Q

Cholesterol esters are broken down into cholesterol and free fatty acids by

A

cholesterol esterase

30
Q

How is the destination of short and medium chain fatty acids different from long chain fatty acids

A

short and medium chain fatty acids go into the portal vein and then into the liver and CVS
whereas long chain fatty acids go into the lymphatic system

31
Q

What is enterohepatic circulation?

A

the recycling of bile

32
Q

What is the role of ezeimbe?

A

Blocks NPC1L1

inhibiting the intake of blood cholesterol

33
Q

What happens to long chain fatty acids in absorption

A

Long-chain fatty acids are re-esterified and combine cholesterol and protein to form chylomicrons (formed in the enterocytes). They enter the lymphatic system via lacteals

34
Q

What are chylomicrons?

A

Chylomicrons are transporting fat through the lymphatic system
Chylomicrons are a type of lipoprotein = lipid core + shell composed of a (specific) apolipoprotein, phospholipids, and free cholesterol

35
Q

What are the 4 main lipoproteins that transport lipids?

A

LDL
HDL
Chylomicrons
VLDL

36
Q

What is the role of LDL?

What is its main component?

A

Carries cholesterol made by the liver and other sources to the cells
cholesterol

37
Q

What is the role of HDL?

What is its main component?

A

Helps remove cholesterol from the cells and in turn excretes cholesterol from the body

protein

38
Q

What is the role of VLDL?

What is its main component?

A

Carries lipids taken up and made by the liver to the cells

triglycerides

39
Q

What is the role of Chylomicrons?

What is its main component?

A

Carries dietary fat from the small intestines to the cells

triglycerides

40
Q

What are the 3 ways cholesterol can be uptaken into the body?

A
  1. scavenger pathway
  2. HDL’s
  3. receptor pathway
41
Q

What is the receptor pathway?

A

LDL are up-taken, broken down and utilized by cells
Excess not taken up and may become oxidized in the blood
LCL binds to the LCL receptor on the cells and is transported into the cell by endocytosis

42
Q

What is the Scavenger pathway?

A

Removes oxidized LDL that can burrow under the endothelium
Can build up over time to form plaque. Plaque is what narrows the blood vessel lumen, increasing risk of blockage. Plaque can also detach and form a clot

43
Q

How does HDL uptake cholesterol?

A

Picks up cholesterol throughout periphery and returns to liver for disposal /recycling

44
Q

What happens when cells have abundant cholesterol?

A

LDL receptor synthesis is blocked for reduced uptake

45
Q

How does LDL contribute to atherosclerotic plaque formation?

A

LDL molecules are oxidized and taken up by macrophages, which become foam cells
These cells often become trapped in the walls of blood vessels and contribute to atherosclerotic plaque formation

46
Q

Plant sterols have the ability to help reduce dietary cholesterol absorption. How is this done?

A

They are incorporated to micelles during digestion, thus reducing the amount of dietary cholesterol in micelles. Absorbed via NPC1L1 like cholesterol, and released back into the lumen via proteins ABCG5 or 8. Travel to colon for excretion

47
Q

What is circulating cholesterol?

A

Circulating cholesterol: from endogenous production, enterohepatic circulation and dietary absorption.

48
Q

What is the main distinction between fats & oils?

A

oils are liquid at room temperature, whilst fats remain solid at room temperature

49
Q

What is the AMDR for total fat?

A

20-25%

Trans an saturated fats limited to 10%

50
Q

What is the SDT for fats?

A

For chronic disease prevention include Omega-3 PUFAs

In adults, LC ω-3 fat should equate to 0.2% of estimated energy requirement, or about 0.6g/day for men and 0.4g/day for women.

51
Q

what is atherosclerosis?

A

plaque block up in the arties causes by LDL bluid up. can lead to blood clots

52
Q

what are the risk factors for atherosclerosis?

A

Dyslipidemia: high triglycerides and high LDL /VLDL cholesterol levels, low HDL, existing hypertension, smoking, physical inactivity, obesity, diabetes

Age, gender, race and genetics

53
Q

What are the blood lipid targets in Australia?

A 
Total cholesterol < 5.5mmol/L
HDL >1.0 (1.2 in Women) mmol/L
LDL <1.8 mmol/L
Non-HDL cholesterol <2.5 mmol/L
Triglycerides <2 mmol/L
54
Q

How do saturated fat and cholesterol in the diet increase the risk of CVD?

A

dietary cholesterol and saturated fat raise blood cholesterol
High blood cholesterol is associated with atherosclerosis, and the incidence of coronary heart disease

NUTR2101 (14 decks)

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