Lecture 10 Flashcards
Cholesterol
A steroid alcohol
critically important component of cell membranes
Not digested into CO2 + H2O
Steroid hormones
derived from cholesterol
Hormones derived from the same 4-ring structure as cholesterol
Triglycerides
Formed from one glycerol molecule with three fatty acid molecules attached via ester bonds
How are triglycerides transported?
through the body by chylomicrons and VLDL (very-low-density-lipoproteins)
Phospholipids
Composed of one glycerol molecule with a phosphate group and two fatty acid molecules attached via ester bonds
Create phospholipid bilayer membrane
Chylomicrons
Has largest diameter, but lowest density
enter the circulation and are metabolized into remnant particles for uptake and further modification by the liver
Chylomicron composition
68% triglycerides, 5% cholesterol, 7% phospholipid, and 2% apolipoprotein (B-48)
Very-low-density lipoproteins (VLDL)
secreted into the blood by the liver for metabolism in peripheral tissues
Very-low-density lipoproteins (VLDL) composition
55% triglycerides, 19% cholesterol, 18% phospholipid, 8% apolipoprotein (c-100)
Intermediate-density lipoproteins (IDL)
transitional form, it is made from VLDL and further modified in the liver to LDL
Low-density lipoprotein(LDL)
primary carrier of cholesterol
brings cholesterol to peripheral cells for membrane synthesis and formation of adrenal and reproductive hormones
What is LDL known as?
Known as “bad” cholesterol,”
easily taken up by cells
high levels are associated with increased risk for atherosclerosis
LDL composition
50% cholesterol, 22% phospholipids, 6% triglycerides, and 22% protein and have apoprotein B-100
High-density lipoprotein (HDL)
synthesized in the intestines and liver cells
Smallest Diameter, largest density
What is HDL known as?
Healthy cholesterol
removes excess cholesterol from peripheral tissues and transports it to other catabolic sites
This function has an anti-atherogenic effect
HDL composition
50% protein, 28% phospholipids, 19% cholesterol, and 3% triglycerides
apolipoproteins A-I, mainly, and A-II
Lipids and Lipoproteins: Clinical significance
Abnormal lipid metabolism can be due to genetic defects, or it can be acquired
associated with risk of coronary heart disease and other disorders
Ranges of Cholesterols
Total: Normal: <200, high >240
HDL: Normal: >60, Risk: >40
LDL: Normal <100, Risk: >190
Triglyceride: Normal: <150, Risk: >500
Type I hyperlipoproteinemia
Elevated chylomicrons
Serum appearance: Creamy layer of chylomicrons
Total cholesterol: Normal to moderately elevated
Triglyceride: Extremely elevated
Apo-B-48 increased, Apo A-IV increased
Type IIa hyperlipoproteinemia
Increased LDL
Serum appearance: Clear
Total cholesterol: Generally elevated
Triglyceride: Normal
Apo-B 100 increased
Type Iib hyperlipoproteinemia
Increased LDL and VLDL
Serum appearance: Clear or slightly turbid
Total cholesterol: Elevated
Triglyceride: Elevated
Apo B-100 increased
Type III hyperlipoproteinemia
Increased IDL
Serum appearance: Creamy layer sometimes present over a turbid layer
Total cholesterol: elevated
Triglyceride: elevated
Apo E-II increased, Apo E-III decreased, and Apo E-IV decreased
Type IV hyperlipoproteinemia
Increased VLDL
Serum appearance: Turbid
Total cholesterol: Normal to slightly elevated
Triglyceride: Moderately to severely elevated
Apo C-II either increased or decreased, and Apo B-100 increased
Type V hyperlipoproteinemia
Increased VLDL with chylomicrons
Serum appearance: Turbid with creamy layer
Total cholesterol: Slightly to moderately elevated
Triglyceride: Severely elevated
Apo C-II increased or decreased, Apo B-48 and Apo B-100 increased
