Final answer:
The Cori cycle is essential during prolonged exercise and involves gluconeogenesis from lactate. It helps regulate blood sugar levels and clears lactic acid from muscles. This cycle does not involve protein decomposition, insulin increase, muscle glycogen breakdown, or fat oxidation.
Step-by-step explanation:
The Cori cycle plays a significant role during prolonged exercise as it allows the body to maintain energy supply when oxygen is limited. This metabolic cycle primarily involves gluconeogenesis from lactate, which is a process where lactate produced in the muscles during anaerobic glycolysis is transported to the liver. There, it is converted back to glucose, which can then be released into the blood and taken up by muscle cells to replenish their energy reserves.
This cycle helps in the regulation of blood sugar levels and the elimination of lactic acid from muscles, preventing acidosis. While glycolysis breaks down carbohydrates into pyruvate to provide energy, in the absence of sufficient oxygen, this pyruvate is converted to lactate in the muscles. The liver then takes up this lactate and converts it back to glucose through gluconeogenesis. It's important to note that this cycle does not directly involve protein catabolism, increased insulin secretion, glycogenolysis in skeletal muscle, or beta-oxidation of fats.