Pharmacology · single question
Through which adrenergic receptors does epinephrine act on the heart and vasculature?
Show answer and explanation
Correct answer: A. Beta-1 receptors increase heart rate and contractility; alpha-1 causes vasoconstriction; beta-2 causes bronchodilation/skeletal-muscle vasodilation
Epinephrine stimulates beta-1 in the heart (raising rate and contractility), alpha-1 in skin/mucosa vessels (vasoconstriction), and beta-2 in bronchi and skeletal-muscle vessels (dilation); alpha-2 mediates negative feedback on norepinephrine release.Other options: Bronchodilation is beta-2 not beta-1; alpha-1 mediates vasoconstriction not heart rate; the heart is driven by beta-1, not beta-2.Key exam takeaway: Cardiac effect of epinephrine = beta-1 (rate and contractility); alpha-1 = vasoconstriction; beta-2 = bronchodilation.