This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pharmacodynamics, Subject name: Pharmacology
[{'content': 'Which of the following terms best describes a drug that blocks the action of adrenaline at its receptors by occupying those receptors without activating them? \nSelect and explain. \nA. Pharmacologic antagonist, B. Non competitive antagonist, C. Physiologic antagonist, D. Chemical antagonist', 'role': 'user'}, {'content': 'Answer: A \nExplanation: * Pharmacological antagonist bind to same receptor and thus blocks the action of the drug e.g. atenolol (a beta receptor antagonist) is pharmacological antagonist of adrenaline. * Physiological antagonist binds to different receptor and produce opposite effect e.g. adrenaline produce bronchodilation by binding to beta 2 receptors whereas histamine cause bronchoconstriction by acting on H1 receptors. Thus adrenaline is physiological antagonist of histamine.', 'role': 'assistant'}]