Lipids Flashcards
(24 cards)
what is a lipoprotein
lipids associated with proteins to serve as transport mechanisms for lipids in lymph and blood
how is water removed from the formation of triglycerides
condensation reaction
functions of lipids
produce heat and energy, form cell membranes
stored as adipose tissue: insulates the body, energy reserve, protects delicate organs
standard methods for measuring triglyceride concentrations?
enzymatic or alkaline hydrolysis to liberate glycerol
is fasting needed for TG test
yes - 12 hr
what is the specimen collection and storage for TG assay
fresh, non haemolysed serum from fasting patients. stable for 3 days at 2-8 degrees. prolonged storage not recommended - other glycerol containing compounds will hydrolyse to release free glycerol
enzymatic reaction for TG
TG + water –lipase–> glycerol + fatty acids
glycerol + ATP –glycerol kinase–> glycerol-3-phosphate + ADP
glycerol -3-phosphate + O2 –G-1-P oxidase–> DAP + H2O2
H2O2 + 4AAP + 4 chlorophenol –peroxidase–> Quinoneimine Dye + 2H2O
these methods = hydrolysis of triglycerides by lipase. Trinder reaction = determines quinoneimine dye - measured at 505n
write a note on cholesterol
found in blood, bile, brain tissue. carried in blood by protein in form of high density lipoprotein (HDL Cholesterol), LDL cholesterol and VLDL cholesterol
essential for forming and maintaining cell membranes , forms several steroid hormones, produces bile salts, conversion into vit D in sun
85% is endogenous in the liver, 15% from diet
is HDL or LDL good
HDL good, LDL bad
what is the problem with cholesterol
special cells catch LDL and deposit the chol on the blood vessel wall - atherosclerosis
what is the role of HDL
collects bad cholesterol and takes it to the liver
what are the two blood tests that determine high cholesterol
total cholesterol, non fasting
lipid profile, fasting- measures total cholesterol, HDL, LDL, TGs
total chol and LDL chol, HDL ref ranges
6.2 mmol/L = high total cholesterol
4.1 mmol/L = high LDL
<0.9 = risk
desirable ranges for TCL, LDL, HDL
TCL 5.2-6.2
LDL 3.1-4.1
HDL 0.9-1.55
what might a very high cholesterol and triglyceride level may mean
inherited hypercholesterolemia or hyperlipidemia, diabetes, hypoparathyroidism, kidney/liver disease
HDL chol > 1.56 = preventative
low cholesterol levels?
liver disease (cirrhosis or hepatitis), malnutrition, hyperthyroidism, where HDL levels <1.04 = inc risk of coronary heart disease
what are the three risk categories and LDL goal
coronary heart disease and diabetes = <2.6mmol/L
multiple risk factors = <3.4mmol/L
zero to one risk factor = <4.1mmol/l
what are the effects of lipids on lipoproteins and CVD risk
dietary chol = no effect on blood cholesterol
saturated fats = raise LDL
trans fats = raise LDL and lower HDL
monounsaturated = lower LDL
omega 3 polyunsaturated fats = lowers blood cholesterol
risk factors of high chol
family history, age, gender, diet, smoking, obesity, diabetes, high BP, stress
who discovered the inverse relationship between serum HDl and CVD
Castelli
HDL chol and TG measurements provides valuable info on predicting CVD and lipoprotein phenotyping
how is HDL determined (assay)
cholesterol esters –esterase–> cholesterol + fatty acids
cholesterol + O2 –oxidase–> cholesten-3-one + H2O2
2H2O2 + 4-Aminoantipyrine + Phenol –peroxidase–> quinoneimine + 4H2O
absorption at 505nm
how is HDL cholesterol sample prepared for testing
serum reacted with polyethylene glycol reagent - LDL and VLDL precipitated. HDL remains in supernatant
what is the electroneg of lipoproteins
see diagram near end
features of lipoprotein electrophoresis
mobility depends on protein content
high protein content = move faster towards anode, lower protein conc = minimal mobility
