You have been provided with a large file of experimental data describing the physiology and structure of a group of neurons in the spinal cord. Which of the following features would support classifying these neurons as sympathetic?

Question

BlackTom AI · Accepted Answer

Sympathetic preganglionic neurons are located in the intermediolateral cell column (lateral horn) of the spinal cord, specifically in the thoracic and upper lumbar segments (classically T1–L2/L3). This thoracolumbar distribution is the defining anatomical hallmark of sympathetic outflow.

Relevant knowledge points and concepts
- Autonomic nervous system divisions: sympathetic (thoracolumbar) vs parasympathetic (craniosacral).
- Location: sympathetic preganglionic cell bodies lie in the lateral horn (IML) of T1–L2; somatic motor neurons lie in the ventral horn.
- Neurotransmitters: sympathetic preganglionic neurons are cholinergic (acetylcholine); most sympathetic postganglionic neurons are noradrenergic (noradrenaline), with exceptions (e.g., sweat glands).
- Functional activity: sympathetic activity increases during exercise (“fight or flight”), not becomes inactive.

Step-by-step reasoning
1. Examine anatomical location option: neurons in thoracic and lumbar segments is precisely the thoracolumbar pattern of sympathetic preganglionic neurons (IML cell column). This matches textbook anatomy and so supports classification as sympathetic.
2. Evaluate neurotransmitter option: “synthesize high levels of noradrenaline” — this describes many sympathetic postganglionic neurons in peripheral ganglia, not the spinal cord cell bodies (preganglionic) which synthesize acetylcholine. Thus this option is incorrect for neurons whose cell bodies are in the spinal cord.
3. Evaluate ventral horn option: ventral horn contains somatic motor neurons controlling skeletal muscle, not autonomic sympathetic preganglionic neurons located in the lateral horn — so ventral horn location would argue against sympathetic identity.
4. Evaluate activity option: sympathetic neurons are typically more active during exercise; becoming inactive during exercise is the opposite of expected sympathetic behavior.

Why the correct answer is correct
The thoracolumbar (T1–L2/L3) location is the canonical anatomical signature of sympathetic preganglionic neurons. Finding cell bodies in those segments (especially in the lateral horn/IML) is direct evidence of sympathetic identity.

Why the other options are incorrect
- “Become inactive during exercise”: false—sympathetic activity increases during exercise.
- “Synthesize high levels of noradrenaline”: incorrect for spinal cord cell bodies (preganglionic neurons are cholinergic); noradrenaline is made by most postganglionic sympathetic neurons.
- “Located in the ventral horn”: ventral horn houses somatic motor neurons, not sympathetic preganglionic neurons.

Conclusion
Therefore, the feature that supports classifying these neurons as sympathetic is that they are located in the thoracic and lumbar segments of the spinal cord, which matches the provided correct answer.

You have been provided with a large file of experimental data describing the physiology and structure of a group of neurons in the spinal cord. Which of the following features would support classifying these neurons as sympathetic?单项选择题

类似问题

Which of the following statements about the sympathetic nervous system is correct?

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When your body prepares you for fight or flight (e.g., eyes dilating, heart pumping),which system in your body is activated?

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The sympathetic division in the autonomic nervous system gives us the fight or flight response.

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