Which of the following neurotransmitters would be the only secretion of the sympathetic preganglionic fibers of the autonomic nervous system?

• A. norepinephrine
• B. acetylcholine
• C. epinephrine
• D. acetylcholinesterase

Answer: (B)

Verified step by step guidance

1. Understand the structure of the autonomic nervous system, which is divided into the sympathetic and parasympathetic divisions. Each division has preganglionic and postganglionic fibers.
2. Recognize that the sympathetic division is responsible for the 'fight or flight' response, and its preganglionic fibers originate in the spinal cord.
3. Identify the neurotransmitter released by sympathetic preganglionic fibers. In the autonomic nervous system, preganglionic fibers, whether sympathetic or parasympathetic, release acetylcholine.
4. Differentiate between preganglionic and postganglionic fibers. Sympathetic postganglionic fibers typically release norepinephrine, but preganglionic fibers release acetylcholine.
5. Conclude that acetylcholine is the neurotransmitter secreted by sympathetic preganglionic fibers, as it is common to both sympathetic and parasympathetic preganglionic fibers.