Lipid Metabolism Review

A comprehensive set of flashcards summarizing key concepts related to lipid metabolism, including storage, utilization, regulatory mechanisms, and metabolic pathways.

What are the key forms in which fatty acids are stored after delivery to tissues?

Fatty acids are stored primarily in the form of triglycerides (TAGs) within adipose tissue.

Under what metabolic state does lipogenesis occur?

Lipogenesis occurs in a post-prandial (well-fed) state.

What triggers lipolysis in adipose tissue?

Lipolysis is triggered by low insulin levels and elevated glucagon and catecholamine levels.

Name the primary hormone responsible for activating hormone-sensitive lipase (HSL) during lipolysis.

Epinephrine (adrenaline) is one of the primary hormones that activates HSL.

What is the role of malonyl-CoA in fatty acid metabolism?

Malonyl-CoA inhibits carnitine palmitoyl transferase I (CPT1), thus preventing fatty acid oxidation while promoting fatty acid synthesis.

What pathways involve free fatty acids (FFA) during lipid metabolism?

FFAs can be utilized for energy via β-oxidation or stored as triglycerides in adipose tissue.

What is the fate of glycerol released during lipolysis?

Glycerol can enter gluconeogenesis to be converted to glucose or be used for glycolysis.

What occurs during the process of β-oxidation of fatty acids?

Fatty acids are broken down in the mitochondria to produce acetyl-CoA, which enters the citric acid cycle.

What are the mechanisms through which AMPK (AMP-activated protein kinase) regulates lipid metabolism?

AMPK promotes increased catabolism and decreased anabolism, enhancing glucose uptake, and β-oxidation while inhibiting lipogenesis.

How does starvation affect ketone body production?

During starvation, acetyl-CoA derived from fatty acids cannot enter the citric acid cycle due to low oxaloacetate, leading to increased ketone body production for energy.

Which type of fatty acids cannot be synthesized by mammals and are considered essential?

Certain long-chain polyunsaturated fatty acids, such as linoleic and alpha-linolenic acid, are essential and must be obtained through diet.

What is the primary site of lipogenesis in the body?

Lipogenesis occurs primarily in the liver and adipose tissue.

What is a significant indicator of energy balance and metabolism in skeletal muscle?

AMPK acts as a sensor of low intracellular ATP levels, influencing energy homeostasis.

What is the relationship between insulin and fatty acid synthesis?

Insulin stimulates fatty acid synthesis by promoting the activity of acetyl-CoA carboxylase (ACC) and enhancing the uptake of glucose into cells.

Describe the Randle Cycle and its significance in metabolism.

The Randle Cycle describes the reciprocal relationship between glucose and fatty acid metabolism, where increased lipolysis can inhibit glucose oxidation, and vice versa.