gluconeogenesen

Gluconeogenesis is a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates. This process occurs primarily in the liver and kidney cortex, serving as a crucial mechanism for maintaining blood glucose levels, especially during periods of fasting or prolonged exercise when carbohydrate intake is insufficient. The substrates for gluconeogenesis include lactate, pyruvate, glycerol, and amino acids. These molecules are converted into glucose through a series of enzymatic reactions. Unlike glycolysis, which breaks down glucose, gluconeogenesis synthesizes it. While many steps are shared with glycolysis, three key irreversible steps in glycolysis are bypassed by different enzymes in gluconeogenesis. For instance, pyruvate carboxylase and phosphoenolpyruvate carboxykinase replace pyruvate kinase. This pathway is energetically demanding, requiring ATP and GTP. It plays a vital role in preventing hypoglycemia and ensuring a continuous supply of glucose for tissues that rely heavily on it, such as the brain and red blood cells. Hormonal regulation, particularly by glucagon and cortisol, stimulates gluconeogenesis, while insulin inhibits it.