Cori cycle
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The Cori cycle, named after its discoverers, Carl Cori and Gerty Cori, refers to the cycling of lactate produced by red blood cells and muscle (during anaerobic respiration) back into glucose.
The cycle
When muscles require energy for short duration or strenuous movements, muscle cells default to anaerobic glycolysis to quickly produce abundant amounts of ATP. The byproduct of anaerobic glycolysis, lactate, diffuses into the blood and is taken up by the liver, where it is converted back into pyruvate by the enzyme lactate dehydrogenase. Pyruvate is then converted back into glucose via gluconeogenesis. The newly formed glucose is released into the blood to be used once again for energy by the red blood cells and muscle. Note that the Cori cycle is energy consuming (4 net ATP used per cycle; there is a 2 ATP gain in the anaerobic glycolysis of glucose and there is a consumption of 6 ATP in the production of glucose via gluconeogensis).