Rasmussen Pharmacology Exam 3 Practice

Atropine works by blocking muscarinic receptors in the heart, especially the M2 receptors that mediate parasympathetic (vagal) effects. The vagus nerve normally slows the SA node and reduces AV node conduction. By antagonizing these receptors, atropine removes this parasympathetic brake, allowing the intrinsic pacing rate to rise and the conduction through the AV node to proceed more quickly. That’s why the primary action is to increase heart rate by inhibiting vagal activity. It does not block sympathetic impulses, so it isn’t best described as decreasing heart rate or as acting chiefly by enhancing AV conduction through sympathetic means.