Question

A) Norepinephrine (NE)

B) Acetylcholine (ACh)

1) Secreted by preganglionic sympathetic fibers.
2) Secreted by preganglionic parasympathetic fibers.
3) Secreted by postganglionic sympathetic fibers to sweat glands.
4) Secreted by postganglionic parasympathetic fibers.
5) Secreted by most postganglionic sympathetic fibers.

Answer 1

Norepinephrine is secreted by various fibers in the sympathetic system, while acetylcholine is secreted by fibers in the parasympathetic system. However, postganglionic sympathetic fibers to sweat glands release acetylcholine instead of norepinephrine.

Step-by-step explanation:

Postganglionic sympathetic fibers secrete norepinephrine (NE) and most postganglionic sympathetic fibers also secrete norepinephrine. Meanwhile, postganglionic parasympathetic fibers secrete acetylcholine (ACh).

Preganglionic sympathetic fibers also secrete norepinephrine, while preganglionic parasympathetic fibers secrete ACh.

However, there are exceptions to this pattern, as postganglionic sympathetic fibers to sweat glands release ACh instead of norepinephrine.