Lipids and Lipid Disorders

Question 1

What kind of compounds are lipids? What are lipids derivatives of? Are lipids hydrophobic or hydrophilic?
What do lipids contribute to?

Answer 1

Natural organic compounds
Fatty acids
Hydrophobic
Cell function and structure

Question 2

How are lipids classified?

Answer 2

• Natural oils
• Fats and waxes
• Sterols (cholesterol) and steroids

Question 3

What is the main structure of fatty acids?
What functional group do esters contain? What length are the carbon chains in fatty acids? What does acid or base-catalyzed hydrolysis yield from a lipid?

Answer 3

Carboxylic acids with a long aliphatic chain
C-OOR
Moderate to long
Fatty acid and alcohol components

Question 4

What is the formula for lauric acid? What is the melting point of myristic acid? What is the formula for palmitic acid? What is the melting point of stearic acid? What is the formula for arachidic acid? What is the melting point of palmitoleic acid?

Answer 4

CH3(CH2)10CO2H
55ºC
CH3(CH2)14CO2H
69ºC
CH3(CH2)18CO2H
0ºC

Question 5

What is the formula for oleic acid? What is the melting point of linoleic acid? What is the formula for linolenic acid? What is the melting point of arachidonic acid?

Answer 5

CH3(CH2)7CH=CH(CH2)7CO2H
-5ºC
CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7CO2H
-49ºC

Question 6

Why are hydrogenated fats difficult for the body to metabolize? Where do hydrogenated fats tend to stick? What process do hydrogenated fats undergo in the bloodstream? What health risks do hydrogenated fats contribute to?

Answer 6

They are different from natural fats
In blood circulation
Oxidation
CVD and cancer

Question 7

What is forced addition of hydrogen into omega-6 polyunsaturated oils called?

Answer 7

Hydrogenation

Question 8

Why is hydrogenation performed? What type of isomers are hydrogenated fats? What type of isomers are natural fats usually?

Answer 8

To solidify oils at room temperature
Trans isomers
Cis

Question 9

What are the three natural forms of food fats?

Answer 9

• Saturated (butter, coconut oil)
• Monounsaturated (olive, canola oils)
• Polyunsaturated (sunflower omega-6, safflower oil, fish omega-3, flaxseed oils)

Question 10

What term describes hydrogenated fats’ processing status? Are hydrogenated fats harmful or beneficial?
What food product is hydrogenated and contains lots of trans fats? When do trans fats form in commercial vegetable oils?

Answer 10

Processed
Harmful
Margarines
When the oils are hydrogenated

Question 11

Which oils are defined as nonhydrogenated vegetable oils? What role do lipids play in healthy diets? What important substances are lipids a source of?

Answer 11

Sunflower, corn, canola, soybean, and olive oils
Important component and source of energy
Fat-soluble vitamins and essential fatty acids

Question 12

Where is energy from lipids stored in our bodies? What do lipids form when combined with proteins? What is a general characteristic of lipids in relation to water? In what type of solvent are lipids soluble?

Answer 12

Adipose tissues
Important constituent of cell membranes
Insoluble
Non-polar solvent

Question 13

What two properties determine a lipid’s melting point? What is the energy content of lipids?
What role do lipids play around the nerve axons? What is the effect of lipids insulating nerve axons?

Answer 13

Chain length and saturation degree
High
Electrical insulators
Can reduce seizure susceptibility

Question 14

What is the state of saturated fatty acids at room temperature? What is the state of unsaturated fats at room temperature?

Answer 14

Solid
Liquid

Question 15

What are pure fats in terms of taste and color?What type of isomerism do lipids produce? Are lipids good or bad conductors of heat?
Bad conductors

Answer 15

Tasteless and colourless
Geometric (cis-trans) isomerism
Bad

Question 16

What products result from hydrolysis of lipids by lipases?

Answer 16

Fatty acids and glycerol

Question 17

What is saponification? What does saponification form?

Answer 17

Hydrolysis of fats by alkali
Soaps

Question 18

What are the main functions of lipids?

Answer 18

• Energy reserves
• Structure of cell membranes
• Regulate membrane permeability
• Act as electrical insulators to the nerve fibres
• Body thermal insulation
• Hormone synthesis
• Source for fat-soluble vitamins (A, D, E, K)
• Components of some enzyme systems
• Act as signalling molecules
• Cholesterol interacts with lipid complexes to maintain membrane fluidity
• Essential fatty acids (linoleic and linolenic acids) are precursors of important metabolites

Question 19

Where is cholesterol synthesized? What is cholesterol necessary for? What percentage of cholesterol is synthesized in the liver? What percentage of cholesterol comes from food?

Answer 19

In the liver
To make bile, steroids, hormones and vitamin D
80%
20%

Question 20

What is cholesterol a main constituent of? What is the dietary recommendation for cholesterol intake? What are some dietary sources of cholesterol? What is the average total body cholesterol content?

Answer 20

Cell membrane
<300 mg/d
Egg yolks, liver, shellfish, meat
150g

Question 21

What percentage of total body cholesterol is part of the cell membrane? What molecule is the precursor for cholesterol synthesis?

Answer 21

90%
Hydroxymethylglutaryl - coenzyme A (HMG-CoA)

Question 22

What enzyme is inhibited by cholesterol in cholesterol synthesis? What effect does lower lipoprotein lipase activity have on cholesterol metabolism?

Answer 22

HMG - CoA reductase
Lower HDL and higher LDL

Question 23

How are fats dissolved in the intestine? What do dissolved fats form in the intestine?

Answer 23

By bile salts
Chylomicrons

Question 24

Where are chylomicrons absorbed? What processes chylomicrons in the blood stream?

Answer 24

Across the small intestine
Lipoprotein lipase

Question 25

What does lipoprotein lipase remove from chylomicrons?

Answer 25

Triglycerides

Question 26

What is formed after triglycerides are removed from chylomicrons?

Answer 26

Chylomicron remnant

Question 27

What processes chylomicron remnants?

Answer 27

Liver

Question 28

What are chylomicron remnants processed into in the liver?

Answer 28

VLDL particles and empty HDL particles

Question 29

What are VLDL cholesterol particles converted into? What do empty HDL particles take from tissues? Where do mature HDL particles go?

Answer 29

LDL Cholesterol and lipids Back to the liver

Question 30

What happens to cholesterol in the liver? Why is HDL known as good cholesterol?

Answer 30

Digested harmlessly HDL carry cholesterol in a healthy direction

Question 31

What percentage of cholesterol is converted to bile acids in the liver? What is cholesterol a precursor for?

Answer 31

50% Steroid hormones, vitamin D & cholestanol

Question 32

Where are triglycerides found? Where else are triglycerides synthesized? What cells use triglycerides for energy production?

Answer 32

Meats, dairy products and cooking oils In the liver Muscle cells

Question 33

Where are triglycerides stored? What happens to excess food intake in relation to triglycerides? When are triglycerides mobilised from adipose tissue?

Answer 33

In adipose tissue Convert to fat, deposit in adipose tissue When energy is needed

Question 34

Which lipoprotein has the least density?

Answer 34

Chylomicrons

Question 35

What do chylomicrons transport? What fluid(s) are chylomicrons soluble in?

Answer 35

Dietary fats from intestine to tissues Both lymphatic fluid and blood

Question 36

What does VLDL stand for? What do VLDLs transport? What does LDL stand for? What does LDL transport? What health condition is LDL correlated with?

Answer 36

Very low-density lipoprotein Fats from liver to tissues Low density lipoprotein Cholesterol into cells Heart disease

Question 37

What does HDL stand for? What does HDL transport? What is the inverse correlation of HDL?

Answer 37

High density lipoprotein Cholesterol to the liver Heart disease

Question 38

What do Chylomicrons and VLDL carry? What do LDL and HDL carry?

Answer 38

Triacylglycerols Cholesterol

Question 39

What is the normal range for total blood cholesterol? What is the normal range for LDL? What is the normal range for HDL?

Answer 39

<200 mg/dl <130 mg/dl >35 mg/dl

Question 40

What are the 3 main pathways for Lipoprotein metabolisms?

Answer 40

1. Exogenous pathway: food lipids 2. Endogenous pathway: lipids synthesized in the liver 3. Reverse cholesterol transport: return of cholesterol from different tissues to liver.

Question 41

What are dietary lipids packaged into in the small intestine cells?

Answer 41

Chylomicrons

Question 42

What is the composition of chylomicrons? How do chylomicrons circulate?

Answer 42

High TG, low cholesterol Via lymph

Question 43

What is a common clinical symptom of gangliosidoses, Krabbe disease, and lysosomal acid lipase deficiency?

Answer 43

Accumulation of lipid in tissues that causes cell damage

Question 44

What is the term for yellow nodule plaques associated with very high VLDL or chylomicron concentrations?

Answer 44

Xanthomatosis

Question 45

Where might yellow nodule plaques appear in patients with severe hyperlipidaemia?


Answer 45

Elbows, knees, back, and buttocks

Question 46

What is a risk associated with hyperlipidemia? What is NOT a risk associated with hyperlipidemia?

Answer 46

Heart disease Anaemia

Question 47

Familial lipid disorders can lead to coronary artery disease at what age?

Answer 47

Young age

Question 48

What is the LDL level associated with Familial defective apolipoprotein B-100? What causes familial hypertriglyceridemia?

Answer 48

160 to 300 mg/dL Lipoprotein lipase mutations

Question 49

What is the cause of inherited abnormal blood lipids in familial dyslipidemia? In addition to medications, what lifestyle changes are recommended for familial dyslipidemia?

Answer 49

A single mutation in one of several genes Limit total fat and cholesterol; physical activity

Question 50

What proportion of the UK population has 5.2 mmol/L or higher serum cholesterol?

Answer 50

2/3

Question 51

What is low HDL related to?

Answer 51

High TG levels

Question 52

How common is heterozygous familial hypercholesterolaemia?

Answer 52

About 1 in 500

Question 53

When does the risk of developing cardiovascular disease increase, regarding blood cholesterol levels? What is a potential cause of hypercholesterolemia related to blood triglyceride levels?

Answer 53

When blood cholesterol levels exceed 200 mg/dl Elevation of Blood triglyceride levels due to elevation of LDL

Question 54

What may increase plasma cholesterol with age? What disorder can cause secondary hypercholesterolemia? What disorder does NOT cause secondary hypercholesterolemia?

Answer 54

Underlying genetic defect or other lipid disorders Diabetes mellitus Osteoporosis

Question 55

What is the primary cause of familial (monogenic) hypercholesterolemia? What happens to plasma LDL and total cholesterol levels in familial hypercholesterolemia? What is the impact of familial hypercholesterolemia in homozygotes? What is the typical cause of death for homozygotes with familial hypercholesterolemia?

Answer 55

Defect of a LDL receptor Increase Most lethal of the inherited disorders Ischaemic heart disease

Question 56

How do plasma cholesterol levels compare to normal in heterozygotes with familial hypercholesterolemia? What determines the expression of the LDL receptor defect in heterozygotes with familial hypercholesterolemia?

Answer 56

Twice the normal levels Environmental and dietary factors

Question 57

What type of disorder is primary hyperlipidemia? What is the cause of secondary hyperlipidemia? What is a cause of secondary hyperlipidemia? What condition can cause hypertriglyceridemia?

Answer 57

Genetic (familial) disorder Diabetes and insulin resistance Hypothyroidism Obesity

Question 58

Elevated plasma triglycerides are due to high levels of what? What is associated with elevated plasma triglycerides?

Answer 58

VLDL Acute pancreatitis

Question 59

Familial endogenous hypertriglyceridemia is caused by over-production of what? What plasma lipid level is typically low in individuals with familial endogenous hypertriglyceridemia?

Answer 59

Hepatic triglyceride HDL

Question 60

What yellow plaque may be caused by hypertriglyceridemia?

Answer 60

Eruptive xanthomata

Question 61

How long should patients fast before specimens are taken for lipid analysis? What factor can affect plasma lipid concentrations and should be avoided before lipid analysis? What type of blood sample should not be used for lipid profile testing?

Answer 61

12 hours Stress Heparinised

Question 62

What measurements are part of a lipid profile test?

Answer 62

LDL-cholesterol, HDL-cholesterol, TG, total cholesterol

Question 63

When should LDL-cholesterol be measured directly rather than calculated?

Answer 63

When plasma triglyceride levels exceed 400 mg/dL

Question 64

What is the mechanism of action of statins?

Answer 64

HMG-Co A reductase inhibitors

Question 65

How do fibrates lower triglyceride levels?

Answer 65

Increase the synthesis of lipoprotein lipase

Question 66

How do bile acid sequestrants lower cholesterol? What is a bile acid sequestrant medication? What is an intestinal cholesterol absorption inhibitor?

Answer 66

Reduce hepatic absorption of bile salts Cholestyramine Probucol

Question 67

What medication is used for secondary hyperlipidemia can cause High LDL levels? What medication is used for secondary hyperlipidemia can cause High Triglycerides? What medication is used for secondary hyperlipidemia can cause Low HDL?


Answer 67

Progestins Estrogens Anabolic steroids

Question 68

What liver enzyme do statins inhibit to lower cholesterol? How do statins control cholesterol production in the liver?

Answer 68

HMG-CoA reductase By inhibiting HMG-CoA reductase

Question 69

What is the multifocal immuno-inflammatory disease in which plaque is produced in the walls of arteries? What is plaque made up of?
What does atherosclerosis cause to the walls of arteries?

Answer 69

Atherosclerosis Fat, cholesterol, calcium, cellular waste, fibrin Hardness and loss of elasticity

Question 70

What does atherosclerosis restrict? What is the result of restricted blood flow due to atherosclerosis?

Answer 70

Blood flow Endothelial dysfunction

Question 71

What are some treatments for atherosclerosis?

Answer 71

Surgery or stents

Question 72

What are the worst consequences of atherosclerosis?

Answer 72

Heart attack and stroke

Question 73

What can happen to plaques in arteries with medication and lifestyle changes?

Answer 73

Plaques may stop growing

Question 74

What is a risk factor for atherosclerosis?

Answer 74

Hyper-triglyceride-emia

Question 75

What type of factors are considered risk factors of hyperlipidemia?

Answer 75

Genetic factors

Question 76

How does smoking affect HDL levels in the blood? How does moderate alcohol intake affect HDL cholesterol?

Answer 76

Lowers the HDL levels May raise the healthy HDL cholesterol

Question 77

How does high alcohol intake affect triglyceride levels? How does overweight and obesity affect cholesterol levels? How does diabetes mellitus affect triglyceride levels? How does liver disease affect cholesterol levels? How does kidney disease affect lipid levels?

Answer 77

Raises the triglyceride levels Rises cholesterol levels Rises triglyceride levels Raise cholesterol levels May elevate cholesterol and triglyceride levels

Question 78

What does metabolic syndrome rise?

Answer 78

Blood pressure, cholesterol, glucose, and increase body weight

Question 79

How do certain medications affect cholesterol levels?


Answer 79

Can increase cholesterol levels

Question 80

In the management of hyperlipidemia, what percentage of total calories should come from fat in a healthy diet? Which of the following meats should be limited in a diet to manage hyperlipidemia? Which oils are recommended to be limited in a diet to manage hyperlipidemia?

Answer 80

Less than 30% Beef Coconut and palm oils

Question 81

What type of dairy products are recommended in a diet to manage hyperlipidemia? Why is both diet and exercise important in managing hyperlipidemia?

Answer 81

Low-fat dairy products To get the right and healthy weight

Question 82

In addition to lifestyle changes, what else is necessary to lower cholesterol levels?

Answer 82

Drug therapy

Question 83

What is a general characteristic of lipid deficiency disorders? What is a potential consequence of lipid deficiency disorders? What percentage of total calories should fats provide to prevent fatty acid deficiency?


Answer 83

Rare Intellectual disability 20-30%

Question 84

What is a symptom of linoleic acid deficiency? What is a symptom of prostaglandin deficiency?

Answer 84

Dermatitis (dry scaly skin) Hand tremors

Question 85

What is a potential consequence of fatty acid deficiency?

Answer 85

Inability to control blood pressure

Question 86

What percentage of cholesterol is converted into bile acids in the liver?

Answer 86

50% of cholesterol is converted into bile acids in the liver.

Question 87

What are bile acids a precursor for?

Answer 87

Bile acids serve as precursors for steroid hormones, vitamin D, and cholestanol.

Question 88

What enzyme is responsible for converting cholesterol into 7α-hydroxycholesterol? What are the two primary bile acids synthesized from 7α-hydroxycholesterol?

Answer 88

The enzyme 7α-Hydroxylase is responsible for this conversion. Cholic acid and Chenodeoxycholic acid.

Question 89

What co-factors are required for the 7α-hydroxylase reaction?

Answer 89

Oxygen (O₂), NADPH, and H⁺.

Question 90

What are the conjugated forms of cholic acid?

Answer 90

Glycocholic acid (when conjugated with glycine) Taurocholic acid (when conjugated with taurine)

Question 91

What happens to cholic acid when it interacts with intestinal bacteria? What happens to chenodeoxycholic acid when it interacts with intestinal bacteria?

Answer 91

It is converted into Deoxycholic acid. It is converted into Lithocholic acid.

Question 92

What are the conjugated forms of chenodeoxycholic acid?

Answer 92

Glycochenodeoxycholic acid (when conjugated with glycine) Taurochenodeoxycholic acid (when conjugated with taurine)