Lipolysis & Beta-oxidation of Fatty Acids

These flashcards cover key concepts related to lipolysis and beta-oxidation of fatty acids, their mechanisms, products, regulation, and clinical implications.

What is lipolysis?

Lipolysis is the hydrolysis of triacylglycerides (TG) to glycerol and free fatty acids.

Where does lipolysis primarily occur?

Lipolysis occurs in the cytoplasm of adipocytes (adipose tissue).

What are the main products of lipolysis?

The products of lipolysis are glycerol and free fatty acids.

What is the fate of glycerol produced from lipolysis?

Glycerol can be used for gluconeogenesis in the liver, intestine, or kidney, and can also be reesterified for lipogenesis.

What is beta-oxidation?

Beta-oxidation is the principal pathway for the catabolism (oxidation) of fatty acids.

Where does beta-oxidation take place?

Beta-oxidation occurs in the mitochondrial matrix of tissues such as adipose tissue, liver, heart, muscles, lungs, kidneys, and testes.

What is the function of carnitine in fatty acid metabolism?

Carnitine facilitates the transport of long-chain fatty acids into the mitochondria by forming acyl-carnitine complexes.

List the three stages of beta-oxidation of fatty acids.

1. Activation of free fatty acids into acyl-CoA. 2. Translocation of acyl-CoA into mitochondria via the carnitine transporter system. 3. Carbon cleavage of acyl-CoA into acetyl-CoA.

What are the energy yields from the oxidation of palmitic acid?

The oxidation of one molecule of palmitic acid (C16) produces 129 ATP molecules.

What role do lipolytic hormones play in lipolysis?

Lipolytic hormones such as catecholamines and glucagon stimulate lipolysis by increasing cAMP concentration.

What is the effect of insulin on lipolysis?

Insulin acts as an anti-lipolytic hormone, lowering cAMP levels and inhibiting hormone sensitive lipase activity.

What diseases can result from carnitine deficiencies?

Carnitine deficiencies can result in muscle cramping, lipid storage myopathy, muscle necrosis, cardiomyopathy, fasting hypoglycemia, and fatty liver.

What is Refsum's disease?

Refsum's disease is a rare neurological disorder caused by the deficiency of α-oxidation enzymes, leading to the accumulation of toxic phytanic acid.

Explain the importance of beta-oxidation.

Beta-oxidation is essential for the metabolism of fatty acids, producing acetyl-CoA for energy production in the TCA cycle.

What is the clinical significance of acyl-CoA dehydrogenase deficiencies?

Acyl-CoA dehydrogenase deficiencies are a treatable cause of pediatric cardiomyopathy.