Lipid Metabolism and Cholesterol Transport

A collection of flashcards covering key concepts related to lipid metabolism and cholesterol transport based on lecture notes.

What are lipids?

A heterogeneous group of compounds including fats, oils, steroids, and waxes.

What is the major storage form of fats in the human body?

Triglycerides (Triacylglycerols) are the major storage form of fats.

What is β-oxidation?

The process by which fatty acids are broken down in the mitochondria to produce acetyl-CoA.

What are the key hormones that activate lipases to promote the breakdown of triglycerides?

Glucagon, Adrenocorticotropic hormone (ACTH), epinephrine, and vasopressin.

What is the role of carnitine in fatty acid metabolism?

Carnitine helps transport long-chain acyl-CoA into the mitochondria for β-oxidation.

What is ketogenesis?

The production of ketone bodies from acetyl-CoA as an alternative energy source when carbohydrate levels are low.

What is the rate-limiting enzyme in ketone body synthesis?

HMG-CoA synthase.

How does alcoholism affect ketone body synthesis?

Alcoholism induces a change in the NADH to NAD+ ratio, affecting gluconeogenesis and leading to ketone body formation.

Why are ketone bodies produced in diabetic ketoacidosis (DKA)?

They are produced as a result of gluconeogenesis-induced depletion of oxaloacetate during periods of starvation or insulin deficiency.

What is the role of HDL in cholesterol transport?

HDL removes excess cholesterol from tissues and transports it back to the liver for excretion or recycling.

What distinguishes LDL from HDL in terms of cholesterol transport?

LDL is known as 'bad cholesterol' as it delivers cholesterol to peripheral tissues, while HDL is 'good cholesterol' that removes excess cholesterol from tissues.

What happens during receptor-mediated endocytosis of LDL?

LDL binds to LDL receptors on liver cells, allowing the uptake of cholesterol from circulating LDL.

Which type of fatty acids must be activated to Acyl-CoA before entering the mitochondrial β-oxidation pathways?

Free fatty acids (FFA) must first be converted to Acyl-CoA.

Why are triglycerides considered impermeable from adipose tissue?

Triglycerides cannot directly cross cell membranes without being broken down into glycerol and free fatty acids by lipases.

What can result from medium-chain fatty acyl CoA dehydrogenase (MCAD) deficiency?

It can lead to impaired fatty acid oxidation, causing metabolic disorders and can be linked to conditions like sudden infant death syndrome.