Unit 5: Lipids

Question 1

____ is the largest category of lipids

Answer 1

Triglycerides

Question 2

Triglycerides and phospholipids can be of ________ origin.

Answer 2

plant and animal

Question 3

What % of all dietary lipids do phospholipids make up?

Answer 3

2%

Question 4

Where are phospholipids used in the body?

Answer 4

• make up part of cell membranes

- involved in fatty acid transport (outer shell of chylomicrons)

Question 5

T or F: phospholipids are soluble in fat but not water

Answer 5

False

soluble in both fat and water

Question 6

What are three food sources of phospholipids?

Answer 6

• egg yolks
• soy beans
• peanuts

Question 7

Sterols are found in _____-based foods

Answer 7

animal

ONLY

Question 8

What are sterols used for in the body?

Answer 8

-precursor to hormones, Vit D, and bile acids

Question 9

How does chain length affect the properties of fatty acids?

Answer 9

• longer = more solid at room temp

- shorter = more liquid at room temp

Question 10

What are the 4 functions of triglycerides?

Answer 10

• energy source
• insulation/protection
• improves bioavailability/transport of other fat-soluble nutrients
• food flavour, texture, odour

Question 11

How many types of fatty acids are there and what are they?

Answer 11

Three:

1. saturated
2. monounsaturated
3. Polyunsaturated

Question 12

A ______ fatty acid has more than one double bond

Answer 12

polyunsaturated

Question 13

A _______ fatty acid has only one double bond

Answer 13

monounsaturated

Question 14

A saturated fatty acid has what structure?

Answer 14

all carbons single bonded to adjacent carbons or 2 H atoms

Question 15

The formula for omega fatty acids are counted from the _____ end

Answer 15

methyl end

Question 16

The ____ end of a fatty acid is referred to as alpha

Answer 16

carboxylic acid

Question 17

What is the difference between trans and cis fatty acids?

Answer 17

cis: hydrogens of DB are on same side, bend in u-shape, more naturally occurring
trans: hydrogens of DB are on opposite sides, more linear

Question 18

For dietary lipids you want to minimize _____ FA intake and maximize ____ FA intake

Answer 18

1. saturated

2. polyunsaturated

Question 19

What is the chemical formula for cholesterol?

Answer 19

C27H45OH

Question 20

T or F: all cells synthesize cholesterol

Answer 20

True

synthesis of cholesterol is especially prevalent in the liver

Question 21

How much cholesterol does your body produce a day (in mg)

Answer 21

1000mg/day

Question 22

What is the use/significance of cholesterol?

Answer 22

• component of cell membranes, neurons

- precursor to molecules

Question 23

How does phytosterols from plants affect cholesterol?

Answer 23

• phytosterols are poorly absorbed
• decrease cholesterol absorption
• ingredient used to reduce cholesterol

Question 24

What enzyme is responsible for breaking down lipids?

Answer 24

-pancreatic lipase

Question 25

Lipid absorption occurs in the ______ and ______

Answer 25

1. duodenum | 2. jejunum

Question 26

How does absorption of small lipids vary from absorption of large lipids?

Answer 26

- small lipids can move directly into bloodstream via thoracic duct - larger lipids combine with bile to form micelles that are water soluble to penetrate watery solution of cells, then lipid can diffuse into cell

Question 27

High density lipoprotein (HDL) has the highest levels of ____ and lowest levels of _____.

Answer 27

1. protein | 2. triglycerides

Question 28

Chylomicrons have the highest levels of _____ and lowest levels of ______.

Answer 28

1. triglycerides | 2. protein

Question 29

After ingestion of lipids, how long until their presence is observed in blood? When does the lipid level peak and when are lipids cleared from the body?

Answer 29

- first seen 1-2 hrs after eating - peak at 3-5 hrs - cleared after 10 hrs

Question 30

What does the liver do in the presence of cholesterol normally?

Answer 30

-liver cells engulf LDL and extract cholesterol

Question 31

What is the main function of LDL?

Answer 31

-delivers cholesterol to synthesize membranes and hormones

Question 32

What are two ways cholesterol can accumulate in the blood?

Answer 32

- increased saturated FA uptake blocks cholesterol receptors in liver - low amounts of LDL receptors in liver to begin with

Question 33

Why is HDL called good cholesterol?

Answer 33

-since it's low in cholesterol (mostly protein), it can absorb cholesterol from blood and plaque

Question 34

How does atherosclerosis develop?

Answer 34

- LDL invades tunica intima, worsens with more free radicals, cholesterol deposits - attracts macrophages, forms foam cells - intima becomes inflamed, sustains cycle

Question 35

What's so bad about foam cells?

Answer 35

- lipid droplets form inside - releases cholesterol crystals which contribute to plaque - injures endothelial cells

Question 36

Why are injured endothelial cells a bad thing?

Answer 36

- they produce nitric oxide from L-arginine - nitric oxide is a potent vasodilator, triggers smooth muscle to relax and increase diameter - with less nitric oxide blood vessels remain constricted

Question 37

What are three sources of food with high [ALA]

Answer 37

- ground flaxseeds - flaxseed oil - walnuts

Question 38

What is the recommended ratio of omega-6:ALA?

Answer 38

4:1 or lower

Question 39

ALA (alpha-linolenic acid) is a _____-based omega-__ fatty acid that is essential.

Answer 39

1. plant | 2. 3

Question 40

What happens to omega-6 FA in the body?

Answer 40

- liver converts into arachidonic acid | - A. acid is precursor to prostaglandins, is pro-inflammatory

Question 41

What are the benefits of the omega-3 derivatives, EPA and DHA?

Answer 41

EPA: cardiovascular benefits DHA: role in brain, neuron and eye development, esp. in infants General: decreases tendency to form blood clots, lowers lipid levels, inhibits atherosclerosis and inflammation

Question 42

The average intake of EPA/DHA is ____mg/day, and to recieve anti-arrhythmic effects would require an intake of ____mg/day

Answer 42

1. 100 | 2. 750