How Are Ketones Produced In The Body?

Share on facebook

Ketone Body Formation

Ketone body formation occurs as an alternative energy source during times of prolonged stress e.g. starvation. It occurs in the liver from an initial substrate of: long chain fatty acids; the fatty acids undergo beta-oxidation by their normal pathway within mitochondria until acetyl-CoA is produced, or ketogenic amino acids; amino acids such as leucine and lysine, released at times of energy depletion, are interconverted only to acetyl-CoA Then, three molecules of acetyl-CoA are effectively joined together in three enzyme steps sequentially catalyzed by: acetyl CoA acetyltransferase HMG-CoA transferase HMG-CoA lyase Coenzyme A is regenerated and the ketone body acetoacetate is formed. Finally, acetoacetate is reduced to another ketone body, D-3-hydroxybutyrate, in a reaction catalyzed by 3-hydroxybutyrate dehydrogenase. This requires NADH. The oxidate state of the liver is such that the forward reaction is generally favoured; this results in more hydroxybutyrate being formed than acetoacetate. Continue reading >>

Share on facebook

Popular Questions

  1. Carlos Danger

    Can someone very generally describe how the brain consumes ketoacids/ketone bodies when blood glucose has been completely depleted?

  2. Jayachandran

    Human body is a glucose driven machine which intake carbohydrates and converts to glucose. Energy is yielded from the glucose and glucose is stored as glycogen. When the carbohydrate intake is somehow reduced then body will shift its mechanism and uses the fatty acids to produce energy. Liver synthesis ketones from fatty acids in our diet or from body fat. Ketones(acetoacetate and acetone) are released into the blood, which is absorbed by the brain and synthesis energy from it through their mitochondria.
    The brain gets a portion of its energy from ketone bodies when glucose is less available (e.g., during fasting, strenuous exercise, low carbohydrate, ketogenic diet and in neonates). In the event of low blood glucose, most other tissues have additional energy sources besides ketone bodies (such as fatty acids), but the brain has an obligatory requirement for some glucose. After the diet has been changed to lower blood glucose for 3 days, the brain gets 25% of its energy from ketone bodies.After about 4 days, this goes up to 70% (during the initial stages the brain does not burn ketones, since they are an important substrate for lipid synthesis in the brain). Furthermore, ketones produced from omega-3 fatty acids may reduce cognitive deterioration in old age. Reference
    When the body starts using the fatty acids for energy production, one problem arises in the brain and that is the blood-brain barrier( barrier that separates the circulating blood from the brain extracellular fluid in the central nervous system )Brain cannot use long chain fatty acids because they cannot cross the blood-brain barrier due to their bondage with albumin. As ketones are medium chain fatty acids which can effectively cross the barrier. So brain uses the ketones for energy production by a process called as ketosis. The ketone bodies are then incorporated into acetyl-CoA and used in the citric acid cycle.
    The citric acid cycle – also known as the tricarboxylic acid (TCA) cycle or the Krebs cycle – is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidation of acetate derived from carbohydrates, fats and proteins into carbon dioxide and chemical energy in the form of adenosine triphosphate (ATP). Reference
    Metabolic pathways to produce energy

  3. inf3rno

    Actually there is fatty acid transport through the BBB. Maybe the rate of this transport is not enough, I don't know, I think it does not really matter.
    What really happens here, that the liver prepares the fatty acids, so the brain can use them more easily in the form of ketoacids to produce energy.
    fatty acid catabolism shared between the liver and the brain - ref

  4. -> Continue reading
read more close

Related Articles

  • How Are Ketones Produced In The Body?

    Sort Draw a simple diagram linking glycolysis, the TCA cycle, triglyceride breakdown and triglyceride synthesis as seen in the liver. Include some of the major substrates, intermediates, and products such as glycerol, DHAP, fatty acyl CoA, malonyl CoA and acetyl CoA. (be able to do this...) Outline the 4 steps involved in the synthesis of triglycerides from glycerol-3-phosphate and activated fatty acids. 1 fatty acid, linked to Acetyl-CoA, is add ...

    ketosis Jan 5, 2018
  • How Are Ketones Produced In Diabetes

    Diabetic ketoacidosis (DKA) is a potentially life-threatening complication of diabetes mellitus.[1] Signs and symptoms may include vomiting, abdominal pain, deep gasping breathing, increased urination, weakness, confusion, and occasionally loss of consciousness.[1] A person's breath may develop a specific smell.[1] Onset of symptoms is usually rapid.[1] In some cases people may not realize they previously had diabetes.[1] DKA happens most often i ...

    diabetes Jan 2, 2018
  • Ketones Are Produced From Quizlet

    Sort The major site of formation of acetoacetate from fatty acids is the: a. adipose tissue. b. intestinal mucosa. c. kidney. d. liver. e. muscle. d. liver. Ketone bodies are formed in the liver and transported to the extrahepatic tissues mainly as: a. acetoacetyl-CoA. b. acetone. c. beta-hydroxybutyric acid. d. beta-hydroxybutyryl-CoA. e. lactic acid. b. acetone. ...

    ketosis Jan 5, 2018
  • How Are Ketones Produced In Dka?

    Certified Diabetes Educator Gary Scheiner offers an overview of diabetic ketoacidosis. (excerpted from Think Like A Pancreas: A Practical Guide to Managing Diabetes With Insulin by Gary Scheiner MS, CDE, DaCapo Press, 2011) Diabetic Ketoacidosis (DKA) is a condition in which the blood becomes highly acidic as a result of dehydration and excessive ketone (acid) production. When bodily fluids become acidic, some of the body’s systems stop functio ...

    ketosis Feb 25, 2018
  • Why Are Ketones Produced?

    On This Site Tests: Urine Ketones (see Urinalysis - The Chemical Exam); Blood Gases; Glucose Tests Elsewhere On The Web Ask a Laboratory Scientist Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, the American Society for Clinical Laboratory Science (ASCLS). Click on the Contact a Scientist button below to be re-directed to the ASCLS site to complete a request form. If your q ...

    ketosis Jan 5, 2018
  • Ketones Are Produced From Cholesterol

    The Keto diet is not really a diet, but rather a lifestyle change. A Ketogenic diet is best described as a low carb, moderate protein, and high fat diet. This combination changes the way energy is used in the body. Fat is converted in the liver into fatty acids and ketone bodies. Another effect of the diet is that it lowers glucose levels and improves insulin resistance. An elevated level of ketone bodies in the blood, a state known as ketosis, l ...

    ketosis Jan 4, 2018

Popular Articles

More in ketosis