Lipids and Lipid Disorders Flashcards
What kind of compounds are lipids? What are lipids derivatives of? Are lipids hydrophobic or hydrophilic? What do lipids contribute to?
Natural organic compounds
Fatty acids
Hydrophobic
Cell function and structure
How are lipids classified?
- Natural oils
- Fats and waxes
- Sterols (cholesterol) and steroids
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?
Carboxylic acids with a long aliphatic chain
C-OOR
Moderate to long
Fatty acid and alcohol components
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?
CH3(CH2)10CO2H
55ºC
CH3(CH2)14CO2H
69ºC
CH3(CH2)18CO2H
0ºC
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?
CH3(CH2)7CH=CH(CH2)7CO2H
-5ºC
CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7CO2H
-49ºC
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?
They are different from natural fats
In blood circulation
Oxidation
CVD and cancer
What is forced addition of hydrogen into omega-6 polyunsaturated oils called?
Hydrogenation
Why is hydrogenation performed? What type of isomers are hydrogenated fats? What type of isomers are natural fats usually?
To solidify oils at room temperature
Trans isomers
Cis
What are the three natural forms of food fats?
- Saturated (butter, coconut oil)
- Monounsaturated (olive, canola oils)
- Polyunsaturated (sunflower omega-6, safflower oil, fish omega-3, flaxseed oils)
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?
Processed
Harmful
Margarines
When the oils are hydrogenated
Which oils are defined as nonhydrogenated vegetable oils? What role do lipids play in healthy diets? What important substances are lipids a source of?
Sunflower, corn, canola, soybean, and olive oils
Important component and source of energy
Fat-soluble vitamins and essential fatty acids
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?
Adipose tissues
Important constituent of cell membranes
Insoluble
Non-polar solvent
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?
Chain length and saturation degree
High
Electrical insulators
Can reduce seizure susceptibility
What is the state of saturated fatty acids at room temperature? What is the state of unsaturated fats at room temperature?
Solid
Liquid
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
Tasteless and colourless
Geometric (cis-trans) isomerism
Bad
What products result from hydrolysis of lipids by lipases?
Fatty acids and glycerol
What is saponification? What does saponification form?
Hydrolysis of fats by alkali
Soaps
What are the main functions of lipids?
- 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
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?
In the liver
To make bile, steroids, hormones and vitamin D
80%
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?
Cell membrane
<300 mg/d
Egg yolks, liver, shellfish, meat
150g
What percentage of total body cholesterol is part of the cell membrane? What molecule is the precursor for cholesterol synthesis?
90%
Hydroxymethylglutaryl - coenzyme A (HMG-CoA)
What enzyme is inhibited by cholesterol in cholesterol synthesis? What effect does lower lipoprotein lipase activity have on cholesterol metabolism?
HMG - CoA reductase
Lower HDL and higher LDL
How are fats dissolved in the intestine? What do dissolved fats form in the intestine?
By bile salts
Chylomicrons
Where are chylomicrons absorbed? What processes chylomicrons in the blood stream?
Across the small intestine
Lipoprotein lipase
What does lipoprotein lipase remove from chylomicrons?
Triglycerides
What is formed after triglycerides are removed from chylomicrons?
Chylomicron remnant
What processes chylomicron remnants?
Liver
What are chylomicron remnants processed into in the liver?
VLDL particles and empty HDL particles
What are VLDL cholesterol particles converted into? What do empty HDL particles take from tissues? Where do mature HDL particles go?
LDL
Cholesterol and lipids
Back to the liver
What happens to cholesterol in the liver? Why is HDL known as good cholesterol?
Digested harmlessly
HDL carry cholesterol in a healthy direction
What percentage of cholesterol is converted to bile acids in the liver? What is cholesterol a precursor for?
50%
Steroid hormones, vitamin D & cholestanol
Where are triglycerides found? Where else are triglycerides synthesized? What cells use triglycerides for energy production?
Meats, dairy products and cooking oils
In the liver
Muscle cells
Where are triglycerides stored? What happens to excess food intake in relation to triglycerides? When are triglycerides mobilised from adipose tissue?
In adipose tissue
Convert to fat, deposit in adipose tissue
When energy is needed
Which lipoprotein has the least density?
Chylomicrons
What do chylomicrons transport? What fluid(s) are chylomicrons soluble in?
Dietary fats from intestine to tissues
Both lymphatic fluid and blood
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?
Very low-density lipoprotein
Fats from liver to tissues
Low density lipoprotein
Cholesterol into cells
Heart disease
What does HDL stand for? What does HDL transport? What is the inverse correlation of HDL?
High density lipoprotein
Cholesterol to the liver
Heart disease
What do Chylomicrons and VLDL carry? What do LDL and HDL carry?
Triacylglycerols
Cholesterol
What is the normal range for total blood cholesterol? What is the normal range for LDL? What is the normal range for HDL?
<200 mg/dl
<130 mg/dl
>35 mg/dl
What are the 3 main pathways for Lipoprotein metabolisms?
- Exogenous pathway: food lipids
- Endogenous pathway: lipids synthesized in the liver
- Reverse cholesterol transport: return of cholesterol from different tissues to liver.
What are dietary lipids packaged into in the small intestine cells?
Chylomicrons
What is the composition of chylomicrons? How do chylomicrons circulate?
High TG, low cholesterol
Via lymph
What is a common clinical symptom of gangliosidoses, Krabbe disease, and lysosomal acid lipase deficiency?
Accumulation of lipid in tissues that causes cell damage
What is the term for yellow nodule plaques associated with very high VLDL or chylomicron concentrations?
Xanthomatosis
Where might yellow nodule plaques appear in patients with severe hyperlipidaemia?
Elbows, knees, back, and buttocks
What is a risk associated with hyperlipidemia? What is NOT a risk associated with hyperlipidemia?
Heart disease
Anaemia
Familial lipid disorders can lead to coronary artery disease at what age?
Young age
What is the LDL level associated with Familial defective apolipoprotein B-100? What causes familial hypertriglyceridemia?
160 to 300 mg/dL
Lipoprotein lipase mutations
What is the cause of inherited abnormal blood lipids in familial dyslipidemia? In addition to medications, what lifestyle changes are recommended for familial dyslipidemia?
A single mutation in one of several genes
Limit total fat and cholesterol; physical activity
What proportion of the UK population has 5.2 mmol/L or higher serum cholesterol?
2/3
What is low HDL related to?
High TG levels
How common is heterozygous familial hypercholesterolaemia?
About 1 in 500
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?
When blood cholesterol levels exceed 200 mg/dl
Elevation of Blood triglyceride levels due to elevation of LDL
What may increase plasma cholesterol with age? What disorder can cause secondary hypercholesterolemia? What disorder does NOT cause secondary hypercholesterolemia?
Underlying genetic defect or other lipid disorders
Diabetes mellitus
Osteoporosis
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?
Defect of a LDL receptor
Increase
Most lethal of the inherited disorders
Ischaemic heart disease
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?
Twice the normal levels
Environmental and dietary factors
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?
Genetic (familial) disorder
Diabetes and insulin resistance
Hypothyroidism
Obesity
Elevated plasma triglycerides are due to high levels of what? What is associated with elevated plasma triglycerides?
VLDL
Acute pancreatitis
Familial endogenous hypertriglyceridemia is caused by over-production of what? What plasma lipid level is typically low in individuals with familial endogenous hypertriglyceridemia?
Hepatic triglyceride
HDL
What yellow plaque may be caused by hypertriglyceridemia?
Eruptive xanthomata
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?
12 hours
Stress
Heparinised
What measurements are part of a lipid profile test?
LDL-cholesterol, HDL-cholesterol, TG, total cholesterol
When should LDL-cholesterol be measured directly rather than calculated?
When plasma triglyceride levels exceed 400 mg/dL
What is the mechanism of action of statins?
HMG-Co A reductase inhibitors
How do fibrates lower triglyceride levels?
Increase the synthesis of lipoprotein lipase
How do bile acid sequestrants lower cholesterol? What is a bile acid sequestrant medication? What is an intestinal cholesterol absorption inhibitor?
Reduce hepatic absorption of bile salts
Cholestyramine
Probucol
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?
Progestins
Estrogens
Anabolic steroids
What liver enzyme do statins inhibit to lower cholesterol? How do statins control cholesterol production in the liver?
HMG-CoA reductase
By inhibiting HMG-CoA reductase
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?
Atherosclerosis
Fat, cholesterol, calcium, cellular waste, fibrin
Hardness and loss of elasticity
What does atherosclerosis restrict? What is the result of restricted blood flow due to atherosclerosis?
Blood flow
Endothelial dysfunction
What are some treatments for atherosclerosis?
Surgery or stents
What are the worst consequences of atherosclerosis?
Heart attack and stroke
What can happen to plaques in arteries with medication and lifestyle changes?
Plaques may stop growing
What is a risk factor for atherosclerosis?
Hyper-triglyceride-emia
What type of factors are considered risk factors of hyperlipidemia?
Genetic factors
How does smoking affect HDL levels in the blood? How does moderate alcohol intake affect HDL cholesterol?
Lowers the HDL levels
May raise the healthy HDL cholesterol
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?
Raises the triglyceride levels
Rises cholesterol levels
Rises triglyceride levels
Raise cholesterol levels
May elevate cholesterol and triglyceride levels
What does metabolic syndrome rise?
Blood pressure, cholesterol, glucose, and increase body weight
How do certain medications affect cholesterol levels?
Can increase cholesterol levels
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?
Less than 30%
Beef
Coconut and palm oils
What type of dairy products are recommended in a diet to manage hyperlipidemia? Why is both diet and exercise important in managing hyperlipidemia?
Low-fat dairy products
To get the right and healthy weight
In addition to lifestyle changes, what else is necessary to lower cholesterol levels?
Drug therapy
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?
Rare
Intellectual disability
20-30%
What is a symptom of linoleic acid deficiency? What is a symptom of prostaglandin deficiency?
Dermatitis (dry scaly skin)
Hand tremors
What is a potential consequence of fatty acid deficiency?
Inability to control blood pressure
What percentage of cholesterol is converted into bile acids in the liver?
50% of cholesterol is converted into bile acids in the liver.
What are bile acids a precursor for?
Bile acids serve as precursors for steroid hormones, vitamin D, and cholestanol.
What enzyme is responsible for converting cholesterol into 7α-hydroxycholesterol? What are the two primary bile acids synthesized from 7α-hydroxycholesterol?
The enzyme 7α-Hydroxylase is responsible for this conversion.
Cholic acid and Chenodeoxycholic acid.
What co-factors are required for the 7α-hydroxylase reaction?
Oxygen (O₂), NADPH, and H⁺.
What are the conjugated forms of cholic acid?
Glycocholic acid (when conjugated with glycine)
Taurocholic acid (when conjugated with taurine)
What happens to cholic acid when it interacts with intestinal bacteria? What happens to chenodeoxycholic acid when it interacts with intestinal bacteria?
It is converted into Deoxycholic acid.
It is converted into Lithocholic acid.
What are the conjugated forms of chenodeoxycholic acid?
Glycochenodeoxycholic acid (when conjugated with glycine)
Taurochenodeoxycholic acid (when conjugated with taurine)
