Question 1

Which of the following statements best explains why cardiac muscle relies primarily on fatty acid oxidation for ATP production under normal physiological conditions?

Accepted Answer

Fatty acid oxidation produces more ATP per molecule than glucose oxidation, supporting the heart's continuous, high ATP demand.

Question 2

During ischemia, which metabolic shift occurs in cardiac muscle and why?

Accepted Answer

Shift from fatty acid oxidation to glucose utilization because glycolysis can proceed anaerobically.

Question 3

Which transporter is responsible for the entry of fatty acids into cardiomyocytes?

Accepted Answer

FAT/CD36

Question 4

What is the primary function of the carnitine shuttle in cardiac muscle metabolism?

Accepted Answer

Transports long-chain fatty acids into the mitochondria for β-oxidation.

Question 5

Which of the following best describes the fate of glycerol released during lipolysis in adipocytes?

Accepted Answer

It is transported to the liver for gluconeogenesis or glycolysis.

Question 6

Which enzyme is activated by both glucagon and epinephrine to promote lipolysis during fasting and exercise?

Accepted Answer

Hormone-sensitive lipase (HSL)

Question 7

What is the main reason fatty acid oxidation is less favored during cardiac ischemia?

Accepted Answer

Fatty acid oxidation requires more oxygen per ATP produced than glucose oxidation.

Question 8

Which apolipoprotein is unique to chylomicrons and is essential for their function?

Accepted Answer

Apo B-48

Question 9

What is the primary function of HDL (High-Density Lipoprotein) in cholesterol metabolism?

Accepted Answer

Reverse cholesterol transport from peripheral tissues to the liver.

Question 10

Which of the following best explains the formation of foam cells in atherosclerosis?

Accepted Answer

Macrophages take up oxidized LDL via scavenger receptors, leading to unregulated cholesterol accumulation.

Question 11

Which of the following equations correctly represents the reaction catalyzed by phosphodiesterases (PDEs) in cAMP signaling?

Accepted Answer

$$cAMP \rightarrow 5'-AMP$$

Question 12

A patient with a genetic deficiency in carnitine would most likely experience which of the following symptoms during prolonged exercise?

Accepted Answer

Reduced ability to oxidize fatty acids, leading to muscle weakness and fatigue.

Question 13

Which of the following best describes the role of LCAT (lecithin:cholesterol acyltransferase) in HDL metabolism?

Accepted Answer

LCAT converts free cholesterol into cholesteryl esters, which move into the hydrophobic core of HDL.

Question 14

Which of the following is a direct consequence of oxidized LDL in the development of atherosclerosis?

Accepted Answer

Oxidized LDL is taken up by macrophage scavenger receptors, leading to foam cell formation.

Question 15

Which of the following best explains why the endothelium becomes functionally permeable in the presence of oxidized LDL?

Accepted Answer

Oxidized LDL triggers inflammation and ROS, reducing nitric oxide and increasing adhesion molecules.

Question 16

Which of the following best describes the metabolic adaptation of the heart during prolonged fasting?

Accepted Answer

Increased utilization of ketone bodies as an efficient fuel source when glucose is limited.

Question 17

Which of the following is the correct sequence for the metabolism of VLDL in the circulation?

Accepted Answer

VLDL $$\rightarrow$$ IDL $$\rightarrow$$ LDL

Question 18

Which of the following best explains the amphipathic nature of lipoproteins and its significance?

Accepted Answer

Amphipathic design allows lipoproteins to transport hydrophobic lipids in the aqueous plasma.

Question 19

A mutation that prevents the expression of Apo B-100 would most directly impair which of the following processes?

Accepted Answer

LDL uptake by peripheral tissues via LDL receptors.

Fuel Utilization and Lipid Transport in Cardiac Muscle

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