Final answer:
Glycogen metabolism is regulated mainly by hormones such as epinephrine, insulin, and glucagon. It is necessary to maintain blood glucose levels and provide a steady energy supply. Epinephrine and glucagon promote the breakdown of glycogen, while insulin stimulates its synthesis.
Step-by-step explanation:
Glycogen metabolism is the process by which glycogen, a polysaccharide stored in liver and muscle cells, is synthesized and broken down to provide glucose for energy. The metabolism of glycogen is stimulated or inhibited by various hormones, which are necessary to maintain blood glucose levels and ensure an adequate energy supply for the body. When energy is required immediately, as in the case of shock or excitement, epinephrine stimulates glycogenolysis (the breakdown of glycogen into glucose), in addition to inhibiting the synthesis of glycogen.
Conversely, insulin promotes glycogenesis (the formation of glycogen from glucose) when there is ample glucose available, allowing glucose to be stored for future energy needs. This process is necessary as it helps maintain energy availability during fasting states or between meals. Additionally, glucagon plays a role by stimulating glycogenolysis in the liver during hypoglycemic conditions to increase blood glucose levels. In muscle cells, the activation of ß-adrenergic receptors by adrenaline leads to the formation of cAMP, which activates mechanisms that mobilize glucose from glycogen stores and make it available for immediate use.