How do dietary carbon sources influence the Cori cycle during intense exercise?

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Multiple Choice

How do dietary carbon sources influence the Cori cycle during intense exercise?

During intense exercise, muscles rely on anaerobic glycolysis, which produces lactate instead of sending pyruvate into the mitochondria. This lactate is released into the bloodstream and travels to the liver, where it is converted back into glucose through gluconeogenesis. That glucose is then released back into the blood to fuel working muscles, completing the Cori cycle. A key point is that this process consumes ATP in the liver, making the cycle energetically costly but effective for maintaining blood glucose during short bursts of high-intensity activity. Dietary carbon sources influence this flux by affecting substrate availability: dietary carbohydrates increase circulating glucose and thus the potential amount of lactate produced during intense effort, feeding the lactate shuttle to the liver. In contrast, fatty acids and ketone bodies (from fat in the diet) are used as alternative fuels and are not part of the lactate-to-glucose shuttle that defines the Cori cycle. So the description that muscle glycolysis yields lactate, which travels to the liver and is converted to glucose via gluconeogenesis (with ATP use) best captures how dietary carbon sources relate to this cycle.

During intense exercise, muscles rely on anaerobic glycolysis, which produces lactate instead of sending pyruvate into the mitochondria. This lactate is released into the bloodstream and travels to the liver, where it is converted back into glucose through gluconeogenesis. That glucose is then released back into the blood to fuel working muscles, completing the Cori cycle. A key point is that this process consumes ATP in the liver, making the cycle energetically costly but effective for maintaining blood glucose during short bursts of high-intensity activity.

Dietary carbon sources influence this flux by affecting substrate availability: dietary carbohydrates increase circulating glucose and thus the potential amount of lactate produced during intense effort, feeding the lactate shuttle to the liver. In contrast, fatty acids and ketone bodies (from fat in the diet) are used as alternative fuels and are not part of the lactate-to-glucose shuttle that defines the Cori cycle. So the description that muscle glycolysis yields lactate, which travels to the liver and is converted to glucose via gluconeogenesis (with ATP use) best captures how dietary carbon sources relate to this cycle.

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