Final answer:
Epinephrine triggers endocrine signaling that affects various organs throughout the body like the liver, where it stimulates the conversion of glycogen into glucose. This process involves hormone-receptor binding, G-protein activation, and the generation of cAMP as a second messenger.
Step-by-step explanation:
The effects of epinephrine on the body, such as its impact on the heart, liver, and blood vessels, is a result of endocrine signaling. This type of signaling involves hormones that are produced by endocrine cells, which may be part of endocrine glands like the adrenal glands that release epinephrine during stress or danger. Such hormones travel through the bloodstream to exert effects on distant cells, like liver cells where epinephrine triggers the conversion of glycogen into glucose, thus increasing blood glucose levels.
The signaling pathway initiated by epinephrine binding to beta-adrenergic receptors on the plasma membrane involves the activation of a G-protein, which subsequently activates adenylyl cyclase. This enzyme converts ATP into cyclic AMP (cAMP), which serves as a second messenger to mediate cell-specific responses. The response in the liver includes the breakdown of glycogen into glucose, which is then released into the bloodstream to provide energy for muscles during the fight-or-flight response.