Lecture 10

A steroid alcohol critically important component of cell membranes Not digested into CO2 + H2O

derived from cholesterol Hormones derived from the same 4-ring structure as cholesterol

Formed from one glycerol molecule with three fatty acid molecules attached via ester bonds

through the body by chylomicrons and VLDL (very-low-density-lipoproteins)

Composed of one glycerol molecule with a phosphate group and two fatty acid molecules attached via ester bonds Create phospholipid bilayer membrane

Has largest diameter, but lowest density enter the circulation and are metabolized into remnant particles for uptake and further modification by the liver

68% triglycerides, 5% cholesterol, 7% phospholipid, and 2% apolipoprotein (B-48)

secreted into the blood by the liver for metabolism in peripheral tissues

55% triglycerides, 19% cholesterol, 18% phospholipid, 8% apolipoprotein (c-100)

transitional form, it is made from VLDL and further modified in the liver to LDL

primary carrier of cholesterol brings cholesterol to peripheral cells for membrane synthesis and formation of adrenal and reproductive hormones

Known as “bad” cholesterol,” easily taken up by cells high levels are associated with increased risk for atherosclerosis

50% cholesterol, 22% phospholipids, 6% triglycerides, and 22% protein and have apoprotein B-100

synthesized in the intestines and liver cells Smallest Diameter, largest density

Healthy cholesterol removes excess cholesterol from peripheral tissues and transports it to other catabolic sites This function has an anti-atherogenic effect

50% protein, 28% phospholipids, 19% cholesterol, and 3% triglycerides apolipoproteins A-I, mainly, and A-II

Abnormal lipid metabolism can be due to genetic defects, or it can be acquired associated with risk of coronary heart disease and other disorders

Total: Normal: <200, high >240 HDL: Normal: >60, Risk: >40 LDL: Normal <100, Risk: >190 Triglyceride: Normal: <150, Risk: >500

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

Increased LDL Serum appearance: Clear Total cholesterol: Generally elevated Triglyceride: Normal Apo-B 100 increased

Increased LDL and VLDL Serum appearance: Clear or slightly turbid Total cholesterol: Elevated Triglyceride: Elevated Apo B-100 increased

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

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

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