Lipids Flashcards
Define lipid associated terminology
Saturated: Chain is full on H. solid at RT
Unsaturated: double bonds in the chains. Liquid at RT
Trans fat: Not typically in nature.
Essential Fatty Acids: must be eaten
Polyunsaturated: 3 or more chains. Membranes
Differentiate among structural characteristics of lipids
Triglycerides: Saturated are from animals, solid at room temp.
unsaturated: plant sources. Liquid at room temp
Uncharged
Explain the usefulness of prostaglandins
They control processes such as inflammation, blood flow, the formation of blood clots and the induction of labour. (this answer brought to you by google)
Explain and compare the lipoproteins using the difference in lipid and protein composition
Chylomicrons
Produced in the the intestine
Transports exogenous (consumed) triglycerides
Large
Captures broken down triglycerides -> taken to liver to store/burn
Scatter light
Buoyant
Core: 84% Triglycerides; 1% cholesterol esters
Discuss lipid metabolism
Triglycerides are eaten, and picked up by chylomicrons for transport to the liver for storage or use, generally storage as adipose tissue. VLDL is converted to LDL by LPL and carries adipose tissue fatty acids to cells for use. HDL removes cholesterols from circulation.
Explain the lipid pathways; include cell and tissue location
1: Absorption Pthwy: Liver releases bile into the intestines
2: Exogenous Pthwy: Chylos transports trigly to liver
3: Endogenous pthwy: VLDL -> LDL, carries trigly from adipose tissue
4: Reverse pthwy: HDL. maintain equilibrium. Remove chol from circ
For the following pre-analytical variations, recognize and explain the effects of each on serum lipid levels
Intra-individual variation
3-5%. Many studies have also documented a seasonal variation. Although
there is discordance between the studies, cholesterol levels tend to be higher in the winter months and
lower in the summer months independent of the country of origin, ethnicity, age, sex, and baseline lipids.
The seasonal variation has been reported to be as high as 12%
(this answer is from the internet. It should be close though)
For the following pre-analytical variations, recognize and explain the effects of each on serum lipid levels
Variation due to age, gender, and race
Under age 20, females have higher
cholesterol levels than males. Adult males between 20 and 45 years of age generally have higher levels
than females of the same age. Total cholesterol, LDL, and triglycerides increase with age for both sexes.
Peak lipid levels for men generally occur between the ages of 40 and 60 and for women, between the ages
of 60 and 80. (this answer is from the internet. It should be close though)
For the following pre-analytical variations, recognize and explain the effects of each on serum lipid levels
Lifestyle/behavior variations
Diet and alcohol – Cholesterol levels are increased by consuming too much dietary fat (particularly saturated or transfat), cholesterol, and calories. Alcohol consumption raises triglycerides and HDL.
Exercise – Regular vigorous exercise affects plasma lipid levels. Exercise lowers the concentration of
triglycerides, VLDL cholesterol, and LDL cholesterol, and raises HDL cholesterol levels.
Drugs – some drugs used to treat high blood pressure may increase triglycerides and decrease HDL cholesterol; oral estrogens (birth control pills) can lower total cholesterol and raise HDL cholesterol. Drugs that alter lipid levels include Beta blockers (particularly unselective Beta blocker like propranolol), bile acid binding resins
(which lower cholesterol and LDL but also raise triglycerides), most protease inhibitors, diuretics, retinoic acid derivatives, and glucocorticoids.
Discuss lipid metabolism in the “fed state” and the “fasting state”
Fed state: Lipase converts dietary lipids and triglycerides into amphipathic molecule that are taken to the liver for conversion into fatty acids for storage in the adipose tissue.
Fast state: Liver empties into the lacteals and eventually the thoracic duct. Apo C2 activates LPL which transports triglycerides derived from adipose tissues.
Describe the most likely cause, clinical significance, and lipid levels associated with hereditary hyperlipidemias
Abnormalities in the LDL receptors result in elevated LDL levels and can lead to hypercholesterolemia and premature atherosclerosis
Explain the cause and/or effect of disorders associated with lipid imbalances
Cardiovascular disease: LDL lvls >=160 md/dl with 1 or less risk factor, or >= 130 with 2 risk factors. Risk factors are family history, hypertension, smoking, diabetes.
Arteriosclerosis: deposition of lipids in the veins. Believed to be caused by damage repair cycle of cells that LDL infiltrates. Can lead to arterial blockages. Measurement of lipid levels key for monitoring.
State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/sources of error, and the usefulness
Cholesterol methods
Cholesterol ester hydrolase cleaves the fatty acids residue from cholesterol esters. the free cholesterol is acted on cholesterol oxidase, producing H2O2. Horseradish peroxidase reacts with this to couple two compounds together, causing a color change which is measured for absorbance.
State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/sources of error, and the usefulness
Trigylcerides
Several ezymatic sequences can be used to cleave glycerol backbone from fatty acids. the fatty acides are then subjected to glycerol phosphitase, which produces the same substrate for horseradish peroxidase to couple for the color change.
State the principle of the chemical reaction, sample types required, reference interval, most common interfering substances/sources of error, and the usefulness
LDL methods
Depends on the precipitation of HDL, which is done through coupling of a cholesterol regent and subjecting to centrifuge spinning, then measured in the same way as cholesterol.
LDL measurement is designated as beta quantification, and involved subtracing the totals for HDL, glycerides, and total cholesterol which gives the final value for LDL.
