APA Dictionary of Psychology

n. an anticholinergic drug derived from certain plants, particularly belladonna (see belladonna alkaloid), and also produced synthetically. Its effects include increases in heart rate and rate of breathing, relaxation of smooth muscles, and reduction of secretions (e.g., saliva). It may be used to treat organophosphate poisoning and bradycardia (slowing of the heart rate), or as an adjunct to anesthesia, but it is most commonly employed in eye examinations to dilate the pupil. Atropine is closely related, chemically and pharmacologically, to scopolamine.