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NUTR2101 > Lipids > Flashcards

Lipids Flashcards

1
Q

Lipids that are liquid at room temperature can be made solid by the process of ____________ to produce________

A

4.

Partial hydrogenation; trans

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2
Q

In the fed state what is the fate of dietary fatty acids?

They are broken down by glucagon into two carbons molecules to form ketones

  1. They compete for energy production with glucose and protein
  2. They are taken into cells by the action of lipoprotein lipase for storage of energy
  3. High insulin delays their uptake into cells to make them available to the liver for lipogenesis
  4. They are oxidised in the blood and engulfed by foam cells
A

.

They are taken into cells by the action of lipoprotein lipase for storage of energy

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3
Q

Which of the following lipoproteins is responsible for transporting cholesterol to tissues?

Chylomicron

  1. Intermediate-density lipoprotein
  2. High-density lipoprotein

Correct4.
Low-density lipoprotein

  1. Very-low-density lipoprotein
A

Low-density lipoprotein

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4
Q

Among the following, the latest health concern for cardiovascular disease risk is:
1.
The high fat in the Mediterrranean diet

  1. Trans fats content in diets
  2. Saturated fats content in diets
  3. High fat content diets
  4. Low fibre content diets
A

Correct2.

Trans fats content in diets

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5
Q

All of the following are functions of dietary fatty acids EXCEPT:
1.
They are constituents of cell membranes

  1. They carry fat soluble vitamins and assist in their absorption
  2. They replace white blood cells when required
  3. They serve as a source of concentrated energy
  4. They are precursors of pro-inflammatory response molecule
A

Correct3.

They replace white blood cells when required

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6
Q

Trans fats are formed by:
1.
Biohydrogenation in ruminants

  1. Heating plant oil at high temperature
  2. None of the above
  3. Partial hydrogenation of plant oils

Correct5.
All of the above

A

Correct5.

All of the above

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7
Q

hich of the following is correct about lipoproteins?

.
VLDL takes cholesterol to the peripheral tissues and LDL transports cholesterol back to the liver for processing

  1. HDL takes cholesterol to the peripheral tissues and VLDL transports cholesterol back to the liver for processing
  2. Chylomicrons take cholesterol to the peripheral tissues and LDL transports cholesterol back to the liver for processing
  3. LDL takes cholesterol to peripheral tissues and HDL transports cholesterol back to the liver for processing
  4. None of these are correct statements about lipoproteins
A

Correct4.

LDL takes cholesterol to peripheral tissues and HDL transports cholesterol back to the liver for processing

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8
Q

1 points

Correct
If a nut and chocolate bar provides 1300 kiloJoules, and contains 15 g of total fat, what percentage of its calories come from fat?

A

~ 44%

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9
Q

Plant sterols can influence blood cholesterol by:

A

Competing for absorption with dietary cholesterol

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10
Q

The structure of the dominant lipid in the diet is

A

Three fatty acids and a glycerol

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11
Q

Which of the following describe fat composition in the Traditional Mediterranean diet?

A

Up to 47% of EER as fat; primarily monounsaturated fatty acids

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12
Q

Which of the following fatty acids are essential?

Answers:
1.
Eicosapentaenoic fatty acids

  1. Oleic fatty acids
  2. Docosahexaenoic fatty acids
  3. Arachidonic fatty acids
  4. Alpha-linolenic fatty acids
A

Correct5.

Alpha-linolenic fatty acids

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13
Q

Although there is mixed information about the optimum ratio of certain fatty acids, the theory supports the idea that ___________ promote pro-inflammatory mediators and _________anti-inflammatory mediators, thus modulating the inflammatory response in the body.

A

Omega 6 fatty acids; omega 3 fatty acids

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14
Q

Which of the following statements about cholesterol is NOT correct:
It is an essential fatty acid

  1. About two thirds of the cholesterol in the body is produced by the liver
  2. Only about 40 to 60% of dietary cholesterol is absorbed
  3. It is only found in animal products
  4. Cholesterol reabsorption may be lowered using soluble fibre
A

1.

It is an essential fatty acid

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15
Q

. Which of the following has been shown to raise blood cholesterol levels?

Cacao butter

  1. Walnut oil
  2. Partially hydrogenated oil
  3. Coconut oil
  4. Palm oil
A

Partially hydrogenated oil

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16
Q

When discussing fatty acid intake in a diet, the____________ rather than the ____________ alone may be of greater importance to address cardiovascular risk.
1.
Processing; types

  1. Quantity; ratio
  2. Types; quantity
  3. Omega method; quantity
  4. Quantity; types
A

Types; quantity

17
Q

What are EFAs? Why are they essential? Describe the omega & delta naming
methodologies for these fatty acids.

A 
Omega 3 ALA and Omega 6 (LA)
Important structural components of cell
membranes: DHA and EPA
• Keep membranes fluid and flexible
DHA /EPA:
• Needed during FETAL DEVELOPMENT and
infancy for:
- Normal development and function of
brain and the retina in the eye
- Normal development and maturation of
the nervous system
• Needed throughout life for:
- Regulation of nerve transmission and
communication
- Important signaling in gene expression
(e.g. APOA1 for HDL lipoprotein
production)
- Important regulation role via eicosanoids
formation

• Important structural components of cell
membranes: DHA and EPA
• Keep membranes fluid and flexible
DHA /EPA:
• Needed during fetal development and
infancy for:
- Normal development and function of
brain and the retina in the eye
- Normal development and maturation of
the nervous system
• Needed THROUGHOUT LIFE for:
- Regulation of NERVE transmission and
communication
- Important signaling in GENE expression
(e.g. APOA1 for HDL lipoprotein
production)
- Important regulation role via eicosanoids
formation
FUNCTION OF LIPIDS: ESSENTIAL FATTY ACIDS
• EFAs are precursors of eicosanoids: = hormonelike molecules. They include: prostaglandins,
prostacyclins, thromboxanes and leukotrienes
• Eicosanoids have over 100 regulatory functions:
cell division, hormonal synthesis and signalling,
regulation of components in and out of the cells,
body temperature, circadian rhythm,
inflammatory response regulation

• Eicosanoids produced from omega-6:
- Influence blood vessels to constrict and raise
blood pressure
- Promote pro-inflammatory response via
prostaglandins and thromboxanes series 2
• Eicosanoids produced from omega-3
- Dilate blood vessels and decrease blood pressure
- Promote anti-inflammatory response via
prostaglandins and thromboxanes series 3
18
Q

. What are eicosanoids? How are they made?

A 
• Eicosanoids produced from omega-6:
- Influence blood vessels to constrict and raise
blood pressure
- Promote pro-inflammatory response via
prostaglandins and thromboxanes series 2
• Eicosanoids produced from omega-3
- Dilate blood vessels and decrease blood pressure
- Promote anti-inflammatory response via
prostaglandins and thromboxanes series 3
19
Q

Functions of Lipids - LIPIDS

A

Provide energy in compact form: 38 kJ/gram
• Insulates and protects the body and organs (by presence of adipocytes)
• Provide cell membrane structure (phospholipids), strength (saturated FA and cholesterol) and
fluidity (PUFA)
• Assist in fat soluble vitamins absorption and transport

20
Q

functio lipids Sterols

A

Ring structure, “Modified steroid”
• Known as cholesterol (in animal), and phytosterol (in plant)
• Cholesterol = Greek for ”bile” and “solid”
• The body of a 70 kg human contains ~ 35 grams cholesterol. Mainly founds in cell membranes
• Functions:
- Cholesterol is a precursor of sex and adrenal hormones (steroids), vitamin D, bile salts (to
make bile)
- Chorlesterol is involved in cell membrane stability and constitutes part of lipoproteins (see
further)
• Sources:
- Endogenous synthesis in the liver, intestine, adrenal glands, and gonads: ~1000 mg/ day =
80% of daily needs)
- Dietary: food of animal origin (egg, dairy, poultry, seafood, meat); provides ~ 300mg /day
based on a typical Western diet. Only ~ 50-60% of this is absorbed because it is in the
esterified form. Plant sterols are only minimally absorbed (see further)
- Endogenous production adjusts to meet daily requirement according to the dietary intake

21
Q

FUnctions of Lipids - PHOSPHOLIPIDS

A

Have hydrophobic and hydrophilic ends
• Are components of cell membranes to protect
the cytosol and the movement of compounds
in and out of cells
• Act as ”emulsifier”

22
Q

CHOLESTEROL REMOVAL FROM THE CIRCULATION

A

LDL bad travels bloodstream delvicer cholesterol cells need it - build up walls arteris , paque
HDL good - helps remove excess cholesterol from cells and tissue s

Scavenger pathway
•HDL removes LDL that have not been taken up by cell to
return it to the liver.
•When too much LDL are circulating, and are not
removed by HDL, they can become oxidized => burrow
under the endothelium and engulfed (scavenged) by
macrophages => these become foam cells in the
process
•These cells often become trapped in the walls of
blood vessels and contribute to the start of
atherosclerotic plaque formation => hardening of
the blood vessel wall => less flexibility to adapt to
changes in blood volume => hypertension
• Narrowing of blood vessel => risk of clot => ischemia
=> stroke
•Nutrition is an obvious target to address dyslipidemia:
low fat diet? Low cholesterol? More fiber? Less sugar?
Plant sterols?

23
Q

PLANT STEROLS: FUNCTIONS

A

Plant sterols are incorporated to micelles during lipids
digestion, thus reducing the amount of dietary
cholesterol in micelles.
Absorbed via NPC1L1 like cholesterol, and released
back into the lumen via proteins ABCG5 /8. Travel to
colon for excretion.
• Consuming 2 to 3 grams per day of plant sterols is
necessary to assist in blood cholesterol management by
interfering with dietary cholesterol absorption.
• 2-3 tablespoons daily of margarine containing plant
sterol is required to reach the 2-3 grams (= significant fat
+ trans-fat). Having more will not have a greater effect.
• Increasing fruit and vegetables in the diet will help too,
or using other functional food (e.g. plant sterol added
to yoghurt).

24
Q

ENTEROHEPATIC CIRCULATION: REABSORPTION OF CHOLESTEROL

A

By promoting the excretion of bile (fiber binds to
bile in the GIT), fiber promotes the reduction of
serum cholesterol, because the liver must then
use blood cholesterol to make new bile to meet
the demands of bile.

25
Q

lipid absorpton

A

Water soluble micelles diffuse their contents at the brush border, into the enterocytes, moving
down a concentration gradient
• Occurs in distal duodenum and jejunum
• Long chain fatty acids are re-esterified and combine to cholesterol and protein to form
chylomicrons in the enterocytes
• Chylomicrons enter the lymphatic system via lacteals
• Short and medium chain fatty acids are absorbed directly via the portal vein bound to
albumin
• In normal conditions, 95% of bile salts from the micelles are reabsorbed in the distal ileum, and
return to the liver via portal vein = enterohepatic circulation => bile salts recycling. As bile salts
are 50% cholesterol. This spares the need to make new bile salts, i.e. new cholesterol.

NUTR2101 (10 decks)

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