Glycolysis cholesterol synthesis, two important ways of utilizing excess glucose when its concentration is high in blood. The rate limiting enzymes catalyzing these reactions perform these functions when they have been dephosphorylated through the action of insulin on the liver cells. Between meals, during fasting, exercise or hypoglycemia, glucagon and epinephrine are released into the blood. This causes liver glycogen to be converted back to G6P, and then converted to glucose by the liver-specific enzyme glucose 6-phosphatase and released into the blood. Glucagon and epinephrine also stimulate gluconeogenesis, which coverts non-carbohydrate substrates into G6P, which joins the G6P derived from glycogen,
Glucose cycle Glucose cycle The glucose cycle (also known as the hepatic futile cycle) occurs primarily in the liver and is the dynamic balance between glucose and glucose 6-phosphate. This is important for maintaining a constant concentration of glucose in the blood stream. The glucose cycle is required for one of the liver functions; the homeostasis of glucose in the blood stream. When the blood glucose level is too high, glucose can be stored in the liver as glycogen. When the level is too low, the glycogen can be catabolised and glucose may re-enter the blood stream. The catabolic process occurs at