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 major facilitator superfamily. In the small intestine (more precisely, in the jejunum), glucose is taken up into the intestinal epithelial cells with the help of glucose transporters via a secondary active transport mechanism called sodium ion-glucose symport via the sodium/glucose cotransporter 1. The further transfer occurs on the basolateral side of the intestinal epithelial cells via the glucose transporter GLUT2, as well as their uptake into liver cells, kidney cells, cells of the islets of Langerhans, nerve cells, astrocytes and tanyocytes. Glucose enters the liver via the vena portae and is stored there as a cellular glycogen. In the liver