Which neurotransmitter is primarily used by the parasympathetic nervous system and neuromuscular junction?

Which neurotransmitter is primarily used by the parasympathetic nervous system and neuromuscular junction?

• A. Dopamine
• B. Acetylcholine
• C. Serotonin
• D. GABA

Answer: (B)

Acetylcholine is the transmitter that serves both the parasympathetic nervous system and the neuromuscular junction. In the parasympathetic division, acetylcholine is released by both preganglionic and most postganglionic neurons to act on muscarinic receptors in target organs, producing calm, resting responses like slowed heart rate and increased digestion. At the neuromuscular junction, motor neurons release acetylcholine into the synapse, where it binds nicotinic receptors on skeletal muscle fibers to trigger depolarization and muscle contraction. The other neurotransmitters listed are important in various brain functions, but they are not the primary mediators at the neuromuscular junction or in parasympathetic effector synapses, so they don’t fit this scenario.

Acetylcholine is the transmitter that serves both the parasympathetic nervous system and the neuromuscular junction. In the parasympathetic division, acetylcholine is released by both preganglionic and most postganglionic neurons to act on muscarinic receptors in target organs, producing calm, resting responses like slowed heart rate and increased digestion. At the neuromuscular junction, motor neurons release acetylcholine into the synapse, where it binds nicotinic receptors on skeletal muscle fibers to trigger depolarization and muscle contraction. The other neurotransmitters listed are important in various brain functions, but they are not the primary mediators at the neuromuscular junction or in parasympathetic effector synapses, so they don’t fit this scenario.