Pyruvic acid is defined as an alpha keto-acid because it contains a ketone bond -- a carbon molecule double bonded to an oxygen molecule, along with a carbon atom bonded to an acid group. The chemical formula CH3COCOOH represents pyruvic acid. This compound easily loses a hydrogen atom to create pyruvate, an essential substance needed to provide energy for several metabolic pathways. The human body produces pyruvic acid during the breakdown of carbohydrates, using it to facilitate other reactions essential to life.
Production
Carbohydrates serve as the main source of energy for the body. When you consume carbohydrates, enzymes in the digestive tract break down the sugar molecules into the simplest form -- glucose, also referred to as blood sugar. Glucose enters the bloodstream and triggers your pancreas to produce and release insulin, a hormone that stimulates the transfer of glucose into the cells. Your body uses some glucose immediately, creating energy in the form of ATP and pyruvic acid through the process known as glycolysis.
Citric Acid Cycle
Because the process of glycolysis produces very little energy, the body converts the pyruvic acid into acetyl CoA. The production of pyruvic acid during glycolysis occurs in the fluid portion, known as the cytosol, of the cell. The pyruvic acid then enters a specialized compartment of the cell, known as the mitochondria, where it combines with carbon dioxide to produce two molecules of acetyl CoA. These facilitate the citric acid cycle that produces more energy for the body to use.
Production of Oxaloacetate Acid
During the first steps of the citric acid cycle, the body converts some pyruvic acid into oxaloacetate acid -- a substance necessary for citric acid completion. In addition, if your body contains plenty of energy stores, the oxaloacetate acid can enter another pathway known as gluconeogenesis, which takes place mainly in the liver cells and facilitates the production of more glucose. In this way, pyruvic acid helps create more sugar to support cells that require more energy, such as the brain cells.
Fermentation
In the absence of oxygen, your cells can perform the process of glycolysis and produce pyruvic acid, but it cannot be converted into acetyl CoA or oxaloacetate acid to enter the citric acid cycle or gluconeogenesis. In this case, your cells convert pruvic acid into lactic acid through a process of fermentation. This usually only occurs during times of high energy demands. As the amount of lactic acid builds up in the muscle cells, the pH drops, causing muscle fatigue. During rest, the lactic acid gets converted back into pyruvic acid and then enters the other cycles.
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