In the sympathetic nervous system, which neurotransmitter is released by preganglionic nerves?

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

Answer: (D)

In the sympathetic nervous system, preganglionic nerves release acetylcholine as their primary neurotransmitter. This occurs in the synapses between the preganglionic neurons, which originate in the spinal cord, and the postganglionic neurons located in sympathetic ganglia.

The release of acetylcholine from preganglionic fibers binds to nicotinic receptors on the postganglionic neurons, leading to the activation of these neurons. This is a critical step in the sympathetic response, as it allows for the transmission of signals that prepare the body for 'fight or flight' responses.

In contrast, postganglionic sympathetic neurons typically release norepinephrine to target organs, which is why it can be a common source of confusion. Understanding this differentiation in the neurotransmitter systems is key for grasping how the sympathetic nervous system functions as a whole.