Disorders of Lipid Metabolism Quiz

Lipid Metabolism Disorders

• Lipids are organic compounds that are poorly soluble in water but miscible in organic solvents.
• Lipids play a critical role in biological life, being structural components in cells and involved in metabolic and hormonal pathways.

Fatty Acids

• Fatty acids are straight-chain carbon compounds of varying lengths.
• Fatty acids can be saturated (no double bonds), monounsaturated (one double bond), or polyunsaturated (more than one double bond).
• Fatty acids can esterify with glycerol to form triglycerides or be non-esterified (NEFAs) or free.

Triglycerides

• Triglycerides are transported from the intestine to various tissues, including the liver and adipose tissue, as lipoproteins.
• Following hydrolysis, fatty acids are taken up, re-esterified and stored as triglycerides.
• Plasma triglyceride concentrations rise after a meal, unlike that of plasma cholesterol.

Phospholipids

• Phospholipids are complex lipids, similar in structure to triglycerides but containing phosphate and a nitrogenous base in place of one of the fatty acids.

Cholesterol

• Cholesterol is a steroid alcohol found exclusively in animals and present in virtually all cells and body fluids.
• Cholesterol is a precursor of numerous physiologically important steroids, including bile acids and steroid hormones.

Lipoproteins

• Lipoproteins are soluble protein complexes that transport lipids in body fluids.
• Lipoproteins can be classified into five main groups: chylomicrons, VLDLs, IDLs, LDLs, and HDLs.

Lipoprotein Classification

• Chylomicrons: largest and least dense lipoproteins, transporting exogenous lipid from the intestine to cells.
• VLDLs: transporting endogenous lipid from the liver to cells.
• IDLs: transient and formed during the conversion of VLDL to LDL.
• LDLs: formed from VLDLs and carrying cholesterol to cells.
• HDLs: densest lipoproteins, involved in the transport of cholesterol from cells back to the liver (reverse cholesterol transport).

Dyslipoproteinemias

• Disorders of plasma lipoprotein are called dyslipoproteinemias.
• Dyslipoproteinemias include hyperlipoproteinemia and hypolipoproteinemia.

Hyperlipoproteinemia

• Hyperlipoproteinemia: elevation of one or more lipoprotein fractions in the plasma.
• According to Frederickson's classification, there are 5 types of hyperlipoproteinemia:
  • Type-1: lipoprotein lipase enzyme deficiency, increased plasma chylomicron and VLDL levels.
  • Type-2a: LDL receptor deficiency, increased plasma LDL cholesterol.
  • Type-2b: overproduction of apo B, increased plasma LDL and VLDL.
  • Type-3: increased IDL.
  • Type-4: increased VLDL.
  • Type-5: increased VLDL and chylomicron.

Hypolipoproteinemia

• Hypolipoproteinemia: condition of decreased lipoprotein fraction.
• Types of hypolipoproteinemia:
  • Familial hypolipoproteinemia: failure in the synthesis of apo B lipoproteins, decreased LDL level.
  • Abetalipoproteinemia: absence of Apo B100, LDL fraction is completely absent.
  • Familial α-lipoprotein deficiency.