Final answer:
High circulating levels of catecholamines can both activate adenylate cyclase and activate cyclic AMP by binding to beta-adrenergic receptors on the cell membrane. Adenylyl cyclase converts ATP to cyclic AMP, which functions as a second messenger that elicits a cell-specific response. The enzyme phosphodiesterase breaks down cyclic AMP, stopping the signal.
Step-by-step explanation:
High circulating levels of catecholamines can both activate adenylate cyclase and activate cyclic AMP. When hormones like epinephrine and norepinephrine bind to beta-adrenergic receptors on the cell membrane, they activate a G-protein, which then activates adenylyl cyclase. Adenylyl cyclase converts ATP to cyclic AMP (CAMP), which serves as a second messenger that mediates a cell-specific response. The enzyme phosphodiesterase breaks down CAMP, terminating the signal.