Which statement correctly describes epinephrine?

• A. A hormone that decreases heart rate
• B. A hormone that reduces blood pressure
• C. A stress hormone that increases heart rate and blood pressure
• D. A digestive enzyme

Answer: (C)

Epinephrine is a stress hormone released by the adrenal medulla during sympathetic activation. It prepares the body for rapid action by acting on different adrenergic receptors. In the heart, it stimulates β1 receptors, increasing heart rate and the strength of contraction, which boosts cardiac output. In many vessels, α1 receptors cause vasoconstriction, raising systemic vascular resistance and blood pressure. In skeletal muscle, β2 receptors promote vasodilation to increase blood flow where needed. The net effect during a stress response is a rise in heart rate and blood pressure. It is not a digestive enzyme, and it does not reduce blood pressure, so describing it as a stress hormone that increases heart rate and blood pressure is accurate.