Final answer:
Sympathetic pre-ganglionic nerves are differentiated from parasympathetic ones by their short fibers, ganglia close to the vertebral column, and the type of neurotransmitter released by postganglionic fibers, which is usually norepinephrine for sympathetic and ACh for parasympathetic.
Step-by-step explanation:
The three characteristics that differentiate sympathetic pre-ganglionic nerves from parasympathetic pre-ganglionic nerves are:
- Length of fibers: Sympathetic pre-ganglionic fibers are relatively short as the sympathetic ganglia are close to the spinal cord, whereas parasympathetic pre-ganglionic fibers are long because their ganglia are located near or within the target organs.
- Location of Ganglia: Sympathetic ganglia are adjacent to the vertebral column, and parasympathetic ganglia are in or near the target organs.
- Neurotransmitter Released: Both sympathetic and parasympathetic pre-ganglionic fibers release Acetylcholine (ACh), but this similarity is not a differentiating factor. Instead, it is important to note that postganglionic parasympathetic fibers release ACh, while postganglionic sympathetic fibers generally release norepinephrine, except in specific cases where they release ACh.
The correct answer to the student's question is d. Type of neurotransmitter released, length of fibers, location of ganglia.