Which chemical substance is unique because it functions as a neurotransmitter when released by neurons and as a hormone when released by glands?
Q1. Which chemical substance is unique because it functions as a neurotransmitter when released by neurons and as a hormone when released by glands?
Answer: Norepinephrine
Explanation: Norepinephrine acts as both a hormone and a neurotransmitter in the sympathetic system; acetylcholine is tempting because it is purely a neurotransmitter.