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Questions and Answers
Which of the following ketone bodies is not metabolized and is instead a side product?
Which of the following ketone bodies is not metabolized and is instead a side product?
What triggers the synthesis of ketone bodies in the liver?
What triggers the synthesis of ketone bodies in the liver?
Which of the following tissues can utilize ketone bodies for energy during fasting?
Which of the following tissues can utilize ketone bodies for energy during fasting?
What is a consequence of disorders in fatty acid oxidation?
What is a consequence of disorders in fatty acid oxidation?
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During ketogenesis, what happens to excess acetyl CoA when the Krebs cycle is diminished?
During ketogenesis, what happens to excess acetyl CoA when the Krebs cycle is diminished?
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Which of the following statements is true about ketolysis?
Which of the following statements is true about ketolysis?
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Which statement regarding the liver's ability to utilize ketone bodies is correct?
Which statement regarding the liver's ability to utilize ketone bodies is correct?
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What effect do ketone bodies have on glucose utilization during fasting?
What effect do ketone bodies have on glucose utilization during fasting?
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What is the primary cause of ketonemia in individuals with uncontrolled type 1 diabetes mellitus?
What is the primary cause of ketonemia in individuals with uncontrolled type 1 diabetes mellitus?
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What symptom is commonly associated with diabetic ketoacidosis due to elevated ketone bodies?
What symptom is commonly associated with diabetic ketoacidosis due to elevated ketone bodies?
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How does the presence of ketone bodies in the blood affect blood pH?
How does the presence of ketone bodies in the blood affect blood pH?
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What leads to the dehydration of the body in cases of diabetic ketoacidosis?
What leads to the dehydration of the body in cases of diabetic ketoacidosis?
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Which of the following conditions can also cause ketoacidosis, apart from uncontrolled diabetes?
Which of the following conditions can also cause ketoacidosis, apart from uncontrolled diabetes?
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Study Notes
Biochemistry and Nutrition (BAN 203) - Lecture 28: Ketone Bodies Metabolism
- Ketone bodies are acetoacetate, 3-hydroxybutyrate, and acetone (a non-metabolized byproduct).
- Ketone bodies are important energy sources for peripheral tissues. They are water-soluble, so they don't require lipoproteins or albumin to be transported.
- This is particularly important during prolonged fasting.
- Ketone bodies are produced in the liver when the amount of acetyl CoA exceeds the liver's oxidative capacity.
- Ketone bodies are used in proportion to their blood concentration by extrahepatic tissues like skeletal and cardiac muscle, and renal cortex.
- The brain can use ketone bodies for energy if blood levels rise sufficiently, which saves glucose.
- Disorders of fatty acid oxidation present with hypoketosis (due to decreased acetyl CoA availability) and hypoglycemia (due to increased reliance on glucose).
- During fasting, the liver is flooded with fatty acids from adipose tissue, leading to high hepatic acetyl CoA.
- Some acetyl CoA enters the Krebs cycle, but excess acetyl CoA is diverted into ketone body synthesis.
- Ketone bodies provide energy for the heart, skeletal muscle, kidney, and brain.
- Ketolysis (breakdown) of ketone bodies in extrahepatic tissues, including the brain, but excludes cells lacking mitochondria (like red blood cells).
- Liver cannot use ketone bodies for fuel because it lacks thiophorase.
- Excessive ketone body production (hyperketonemia) is a symptom of uncontrolled type 1 diabetes mellitus. High levels of ketones can also be seen in prolonged fasting.
- Excessive ketone body formation leads to ketonemia (high in blood) and ketonuria (high in urine).
- In severe diabetic ketosis, urine excretion can reach 5000mg/24 hrs and blood concentration can rise to 90 mg/dl. Normal levels are less than 3 mg/dl.
- A fruity odor on the breath is a symptom of diabetic ketoacidosis due to increased acetone production.
- Ketone bodies are acidic; their buildup results in acidemia (acidosis). Each ketone body releases a proton, lowering the body's pH.
- Excretion of glucose and ketone bodies in the urine causes dehydration.
- Increased H+ ions in reduced plasma volume cause severe acidosis (ketoacidosis).
Specific Objectives
- Students should understand ketone bodies, their origin, and formation.
- Students should differentiate between ketogenesis and ketolysis.
- Students should understand the relationship between ketone bodies and diabetes.
Reference Material
- Lippincott's Illustrated Reviews Biochemistry (5th or 6th edition) by Champe, Harvey, and Ferrier (2005)
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Description
This quiz covers the metabolic processes related to ketone bodies, including their production and utilization in the body, especially during fasting. Understand the roles of acetoacetate, 3-hydroxybutyrate, and acetone in energy metabolism and their implications in disorders of fatty acid oxidation.
