Final answer:
The difference in the consequences of epinephrine on heart cells and liver cells stems from their distinct responsivity to epinephrine, which is dictated by the types of adrenergic receptors they possess.
Step-by-step explanation:
The consequence of epinephrine is so different for heart cells and liver cells because they have different types of adrenergic receptors and therefore respond to epinephrine in ways that are specific to their roles in the body's fight-or-flight response. In heart cells, epinephrine binds to β-adrenergic receptors, which increases heart rate and force of contraction. In contrast, in liver cells, epinephrine binds to these receptors and activates a signaling pathway that involves adenylyl cyclase, which in turn increases blood glucose levels by converting glycogen to glucose. This intricate system ensures that, during stress, muscles get more oxygen and glucose to prepare for action.