Final answer:
Epinephrine acts on the liver's β-adrenergic receptors, triggering a G-protein which then activates adenylyl cyclase to convert ATP into cAMP, leading to the breakdown of glycogen and release of glucose into the bloodstream.
Step-by-step explanation:
Epinephrine Receptors on Liver Cells
Epinephrine mediates the fight-or-flight response in the body by acting on different types of adrenergic receptors. When it comes to the liver, epinephrine mainly uses β-adrenergic receptors. These are G-protein coupled receptors that activate the adenylyl cyclase enzyme. This enzyme converts ATP into cyclic AMP (cAMP), which serves as a secondary messenger. cAMP then promotes a series of intracellular events that lead to the mobilization of energy by breaking down glycogen into glucose, thus increasing the amount of glucose available to muscles.
Different regions of the liver have specialized cells that respond to chemical messengers like epinephrine. This hormone-binding event triggers a signaling pathway involving the MAP-kinase cascade and influences various aspects of cellular metabolism and protein expression.