Final answer:
Nicotine is the substance that triggers the release of epinephrine and norepinephrine, enhancing alertness and reducing appetite by acting as a stimulant in the body.
Step-by-step explanation:
By triggering the release of epinephrine and norepinephrine, nicotine boosts alertness and diminishes appetite. Nicotine is a type of stimulant that works by mimicking the action of the neurotransmitter acetylcholine, which leads to the release of epinephrine and norepinephrine from the adrenal glands. These catecholamines increase heart rate, dilate blood vessels, and subsequently enhance alertness while suppressing appetite. Unlike barbiturates, THC, heroin, and alcohol, which have depressant effects on the central nervous system, nicotine has a stimulant effect that aligns with the described consequences of adrenaline release.