Which of the following best describes epinephrine's mechanism of action?

• A. Stimulates nervous system causing bronchodilation and vasoconstriction
• B. Increases insulin release
• C. Blocks beta receptors
• D. Acts as an anticoagulant

Answer: (A)

Epinephrine acts as a nonselective adrenergic agonist, activating both alpha and beta receptors to produce sympathetic effects. Bronchodilation comes from beta-2 receptor stimulation in the airway smooth muscle, while vasoconstriction comes from alpha-1 receptor stimulation in blood vessels. It also increases heart rate and contractility via beta-1 receptors and raises blood glucose by promoting glycogen breakdown and reducing insulin release. The description of stimulating the nervous system with bronchodilation and vasoconstriction captures these core actions. It does not increase insulin release, it does not block beta receptors, and it is not an anticoagulant.