Which medication blocks the parasympathetic nervous system?

Which medication blocks the parasympathetic nervous system?

• A. Epinephrine
• B. Acetylcholine
• C. Dopamine
• D. Atropine

Answer: (D)

Pharmacologic blockade of the parasympathetic system is achieved with anticholinergic drugs that block muscarinic acetylcholine receptors. Atropine is a muscarinic antagonist, so it prevents acetylcholine from binding to those receptors and executing parasympathetic effects. This shifts the autonomic balance toward sympathetic activity, producing effects like increased heart rate, reduced secretions, bronchodilation, and pupil dilation. The other options do not block parasympathetic signaling: epinephrine stimulates adrenergic receptors (enhancing sympathetic tone), acetylcholine would activate parasympathetic pathways, and dopamine is not a primary parasympathetic blocker.

Pharmacologic blockade of the parasympathetic system is achieved with anticholinergic drugs that block muscarinic acetylcholine receptors. Atropine is a muscarinic antagonist, so it prevents acetylcholine from binding to those receptors and executing parasympathetic effects. This shifts the autonomic balance toward sympathetic activity, producing effects like increased heart rate, reduced secretions, bronchodilation, and pupil dilation. The other options do not block parasympathetic signaling: epinephrine stimulates adrenergic receptors (enhancing sympathetic tone), acetylcholine would activate parasympathetic pathways, and dopamine is not a primary parasympathetic blocker.