6 Questions
What is the maximum concentration of ketone bodies in the blood of a well-carbohydrate-fed human?
0.2 mmol/L
Which process does not occur inside the liver regarding ketone bodies?
Excretion through the lungs
Which of the following is a primary fate of ketone bodies outside the liver?
Reforms acetyl-CoA for energy production in extrahepatic tissues
At which blood concentration of ketone bodies does the pathway for reforming acetyl-CoA in extrahepatic tissues become saturated?
12 mmol/L
Which of the following tissues primarily uses ketone bodies as a fuel?
Heart and skeletal muscles
What happens to acetoacetate formed in the liver?
It serves as a precursor for cholesterol synthesis
Study Notes
Ketone Bodies in the Human Body
- In a well-carbohydrate-fed human, the blood concentration of ketone bodies does not exceed 0.2 mmol/L.
Fate of Ketone Bodies
- Inside the liver:
- Acetoacetate is used as a precursor in cholesterol synthesis.
- Outside the liver:
- Ketone bodies are excreted through the lungs (mainly acetone) and kidneys.
- Ketone bodies are converted back to acetyl-CoA in extrahepatic tissues, which then enters the citric acid cycle for energy production.
- Ketone bodies serve as a fuel for extrahepatic tissues, primarily the heart, skeletal muscles, and brain.
- The pathway from ketone bodies to energy production is saturated at a concentration of approximately 12 mmol/L.
Ketone Body Flow
- The liver produces ketone bodies, which are then transported to the blood.
- In the blood, ketone bodies are either excreted through the lungs and kidneys or transported to extrahepatic tissues.
- In extrahepatic tissues, ketone bodies are converted back to acetyl-CoA, which enters the citric acid cycle for energy production, ultimately producing 2CO2.
Learn about the fate of ketone bodies in the liver and outside the liver, including their excretion and reformation into acetyl-CoA.
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