Which statement about the effect of epinephrine on the heart is true?

Which statement about the effect of epinephrine on the heart is true?

• A. It slows heart rate
• B. It has no effect on blood pressure
• C. It decreases contractility
• D. It increases heart rate and blood pressure

Answer: (D)

Epinephrine boosts both heart activity and vascular tone by acting on adrenergic receptors. In the heart, it stimulates beta-1 receptors, increasing heart rate (positive chronotropy) and the strength of contraction (positive inotropy), which raises cardiac output. It also enhances conduction through the electrical pathways. In the vessels, alpha-1 receptor activation causes vasoconstriction, raising systemic vascular resistance and thus blood pressure. Because of these actions, the statement that epinephrine increases heart rate and blood pressure is true. It does not slow heart rate or decrease contractility; rather, it tends to increase both.

Epinephrine boosts both heart activity and vascular tone by acting on adrenergic receptors. In the heart, it stimulates beta-1 receptors, increasing heart rate (positive chronotropy) and the strength of contraction (positive inotropy), which raises cardiac output. It also enhances conduction through the electrical pathways. In the vessels, alpha-1 receptor activation causes vasoconstriction, raising systemic vascular resistance and thus blood pressure. Because of these actions, the statement that epinephrine increases heart rate and blood pressure is true. It does not slow heart rate or decrease contractility; rather, it tends to increase both.