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6.4.4: Ketone Body Synthesis

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    1495
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    In cases where there is not enough glucose available for the brain (very low carbohydrate diets, starvation), the liver can use acetyl-CoA, primarily from fatty acids (but also certain amino acids), to synthesize ketone bodies (ketogenesis). The structures of the three ketone bodies; acetone, acetoacetic acid, and beta-hydroxybutyric acid, are shown below.

    Figure 6.341.png

    Figure 6.341 The three ketone bodies from top to bottom (acetone, acetoacetic acid, and beta-hydroxybutyric acid1)

    After they are synthesized in the liver, ketone bodies are released into circulation where they can travel to the brain. The brain converts the ketone bodies to acetyl-CoA that can then enter the citric acid cycle for ATP production, as shown below.

    Figure 6.342 .png

    Figure 6.342 The production, release, use, or exhalation of ketone bodies2

    If there are high levels of ketones secreted, it results in a condition known as ketosis or ketoacidosis. The high level of ketones in the blood decreases the blood’s pH, meaning it becomes more acidic. It is debatable whether mild ketoacidosis is harmful, but severe ketoacidosis can be lethal. One symptom of this condition is fruity or sweet smelling breath, which is due to increased acetone exhalation.

    References & Links

    1. en.Wikipedia.org/wiki/File:Ketone_bodies.png
    2. commons.wikimedia.org/wiki/File:Liver.svg

    This page titled 6.4.4: Ketone Body Synthesis is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Brian Lindshield via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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