The following metabolic processes serve to regulate the production, metabolism, and storage of carbohydrates within the body:
- Glycogenolysis: The breakdown or hydrolysis of glycogen in the liver (as well as kidneys, muscle and brain) into glucose which is released into the bloodstream.
- Glycolysis: The oxidative breakdown or metabolism of glucose to produce energy
- Glycogenesis: The conversion of excess glucose into glycogen as a cellular storage mechanism.
- Gluconeogenesis: The reversal of glycogenolysis whereby glucose is synthesized within the body from non-carbohydrate substances, such as pyruvate, lactate, glycerol, and certain amino acids.
Several hormones are involved in carbohydrate metabolism. The following are the main hormones that affect carbohydrate metabolism:
- Pancreatic insulin: Insulin is the main regulatory hormone produced and secreted by the pancreatic beta cells. It stimulates the uptake of glucose and the movement of glucose from blood to cells for energy production. Insulin also stimulates glycogenesis, inhibits glycogenolysis, and regulates protein synthesis.
- Pancreatic glucagon: Glucagon is a hormone produced by the alpha cells of the pancreas and stimulates glycogenolysis and gluconeogenesis, causing an increase in blood glucose. It has the opposite effect as that of insulin.
- Adrenal gland cortisol: Cortisol is a steroid hormone produced by the adrenal gland and promotes gluconeogenesis. It is released in response to stress and low blood glucose levels. It functions to increase blood glucose through gluconeogenesis.
- Epinephrine: Epinephrine is a hormone produced by both the adrenal glands and certain neurons. It serves as a neurotransmitter that increases glycogenolysis.
