Ketone bodies are three water-soluble compounds that are produced as by-products when fatty acids are broken down for energy in the liver and kidney. In Chemistry, especially Biochemistry, a fatty acid is a Carboxylic acid often with a long unbranched Aliphatic tail ( chain) which In Physics and other Sciences energy (from the Greek grc ἐνέργεια - Energeia, "activity operation" from grc ἐνεργός The liver is a vital organ in the human body and is present in Vertebrates and some other animals The kidneys are complicated organs that have numerous biological roles They are used as a source of energy in the heart and brain. The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain In the brain, they are a vital source of energy during fasting. Fasting is primarily the act of willingly abstaining from some or all Food, Drink, or both for a period of time
The three ketone bodies are acetone, acetoacetic acid, and beta-hydroxybutyric acid, although beta-hydroxybutyric acid is not technically a ketone but a carboxylic acid. Acetone (also known as propanone, dimethyl ketone, 2-propanone, propan-2-one and β-ketopropane) is a colorless mobile flammable Acetoacetic acid is the Organic compound with the formula CH3C(OCH2CO2H beta -Hydroxybutyric acid ( beta -hydroxybutyrate or 3-hydroxybutyric acid is a Ketone body. beta -Hydroxybutyric acid ( beta -hydroxybutyrate or 3-hydroxybutyric acid is a Ketone body. A ketone (pronounced as key tone) is either the Functional group characterized by a Carbonyl group (O=C linked to two other Carbon atoms or Carboxylic acids are Organic acids characterized by the presence of a Carboxyl group, which has the formula -C(=OOH usually written -COOH or -CO2H
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Uses in the heart and brain
Ketone bodies can also be used for energy. Ketone bodies are transported from the liver to other tissues, where acetoacetate and beta-hydroxybutyrate can be reconverted to acetyl-CoA to produce energy, via the Krebs cycle. The liver is a vital organ in the human body and is present in Vertebrates and some other animals Acetoacetic acid is the Organic compound with the formula CH3C(OCH2CO2H beta -Hydroxybutyric acid ( beta -hydroxybutyrate or 3-hydroxybutyric acid is a Ketone body. Acetyl-CoA is an important molecule in metabolism used in many biochemical reactions The citric acid cycle, also known as the tricarboxylic acid cycle ( TCA cycle) or the Krebs cycle, (or rarely the Szent-Györgyi–Krebs cycle
The heart gets little energy from ketone bodies, it uses mainly fatty acids. The heart is a muscular organ in all Vertebrates responsible for pumping Blood through the Blood vessels by repeated rhythmic
The brain gets its energy from ketone bodies when insufficient glucose is available (e. The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain Glucose (Glc a Monosaccharide (or simple Sugar) also known as grape sugar, is an important Carbohydrate in Biology. g. , when fasting). Fasting is primarily the act of willingly abstaining from some or all Food, Drink, or both for a period of time In the event of low blood glucose, most other tissues have additional energy sources besides ketone bodies (such as fatty acids), but the brain does not. Blood sugar, used in a physiological context is a misnomer and misleading After the diet has been changed to lower blood glucose for 3 days, the brain gets 30% of its energy from ketone bodies. After 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). Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble The brain retains some need for glucose, because ketone bodies can be broken down for energy only in the mitochondria, and brain cells' long thin axons are too far from mitochondria. In Cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed Organelle found in most eukaryotic cells. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell
Production
Ketone bodies are produced from acetyl-CoA (see ketogenesis) mainly in the mitochondrial matrix of liver cells when carbohydrates are so scarce that energy must be obtained from breaking down fatty acids. Acetyl-CoA is an important molecule in metabolism used in many biochemical reactions Acetyl-CoA is an important molecule in metabolism used in many biochemical reactions Ketogenesis is the process by which Ketone bodies are produced as a result of fatty acid breakdown. In Cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed Organelle found in most eukaryotic cells. The liver is a vital organ in the human body and is present in Vertebrates and some other animals Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Fatty acids are an important source of Energy for many organisms
Acetone is formed from spontaneous decarboxylation of acetoacetate. Acetone (also known as propanone, dimethyl ketone, 2-propanone, propan-2-one and β-ketopropane) is a colorless mobile flammable Decarboxylation is any Chemical reaction in which a Carboxyl group (-COOH is split off from a compound as Carbon dioxide (CO2 In a corresponding manner, the levels of acetone are much lower than those of the other two types of ketone bodies. And, unlike the other two, acetone cannot be converted back to acetyl-CoA, so it is excreted in the urine and exhaled (it can be exhaled readily because it has a high vapor pressure and thus evaporates easily). Urine is a liquid waste product of the body secreted by the Kidneys by a process of filtration from Blood and Excreted through the Urethra. Vapor pressure (also known as equilibrium vapor pressure or saturation vapor pressure) is the Pressure of a Vapor in equilibrium The exhalation of acetone is responsible for the characteristic "fruity" odour of the breath of persons in ketotic states. Acetone (also known as propanone, dimethyl ketone, 2-propanone, propan-2-one and β-ketopropane) is a colorless mobile flammable
Ketosis and ketoacidosis
Any production of these compounds is called ketogenesis, and this is necessary in small amounts. Ketogenesis is the process by which Ketone bodies are produced as a result of fatty acid breakdown.
But, when excess ketone bodies accumulate, this abnormal (but not necessarily harmful) state is called ketosis. Ketosis (kiːˈtoʊsɪs is a state in Metabolism occurring when the Liver excessively converts fat into fatty acids and Ketone Ketosis can be quantified by sampling the patient's exhaled air, and testing for acetone by gas chromatography. Gas-liquid chromatography (GLC, or simply gas chromatography (GC, is a type of Chromatography in which the mobile phase is a carrier gas usually an Inert [1] Many diabetics self test for the presence of Ketones using blood or urine testing kits.
When even larger amounts of ketone bodies accumulate such that the body's pH is lowered to dangerously acidic levels, this state is called ketoacidosis. Ketoacidosis is a type of metabolic Acidosis which is caused by high concentrations of Ketone bodies, formed by the Deamination of Amino acids
Impact upon pH
Both acetoacetate and beta-hydroxybutyrate are acidic, and, if levels of these ketone bodies are too high, the pH of the blood drops, resulting in ketoacidosis. In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are pH is the measure of the acidity or alkalinity of a Solution.
This happens in untreated Type I diabetes (see diabetic ketoacidosis), and also in alcoholics after binge drinking, subsequent starvation, and the alcohol-induced impairment of the liver's ability to generate glucose (gluconeogenesis)(see alcoholic ketoacidosis). Diabetes mellitus (ˌdaɪəˈbiːtiːz or /ˌdaɪəˈbiːtəs/ /məˈlaɪtəs/ or /ˈmɛlətəs/ often referred to simply as diabetes ( Ancient Greek: grc Diabetic ketoacidosis (DKA is a life-threatening complication in patients with diabetes mellitus Alcoholism is a term with multiple and sometimes conflicting definitions Ketoacidosis is a type of metabolic Acidosis which is caused by high concentrations of Ketone bodies, formed by the Deamination of Amino acids
See also
- Fatty acid metabolism
- Ketogenesis
- Ketosis
- Ketones (General article. Fatty acids are an important source of Energy for many organisms Ketogenesis is the process by which Ketone bodies are produced as a result of fatty acid breakdown. Ketosis (kiːˈtoʊsɪs is a state in Metabolism occurring when the Liver excessively converts fat into fatty acids and Ketone A ketone (pronounced as key tone) is either the Functional group characterized by a Carbonyl group (O=C linked to two other Carbon atoms or Not limited to the three ketones occuring in the body).
References
- ^ K. Musa-Veloso, S. S. Likhodii and S. C. Cunnane (2002). "Breath acetone is a reliable indicator of ketosis in adults consuming ketogenic meals". Am J Clin Nutr 76 (1): 65-70.
External links
- Atkins Nutritionals, Inc. Lipolysis and Ketosis
- emerg/135 at eMedicine - Diabetic Ketoacidosis
- Fat metabolism at unisanet.unisa.edu.au
- NHS Direct Online Health Encyclopaedia, Ketosis
- BioCarta Pathways Formation of Ketone Bodies
- MeSH Ketone+Bodies
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