Key Terms

amphetamines: potentially addictive stimulant substances that affect the serotonin, epinephrine, norepinephrine, and dopamine levels in the brain.

autonomic nervous system (ANS): in contrast to the central nervous system (CNS), this system regulates many of the body’s functions that generally operate without us having to consciously think about them (autonomous functions); it is functionally divided between the complementary sympathetic and parasympathetic systems, as well as the enteric nervous system.

caffeine: widely used central nervous system stimulant substance found in food and beverage products that can cause anxiety and sleep disorders.

cocaine: psychoactive stimulant drug derived from natural plant sources; high addictive potential. “Crack” is a form of cocaine.

dopamine: one of the major neurotransmitters; a precursor of epinephrine in the human body.

energy drinks: beverage containing stimulant substances, usually caffeine; may contain other stimulants and sugar, as well.

epinephrine: both a hormone and medication (also called adrenalin as it is produced by the adrenal gland) but also an excitatory neurotransmitter produced by certain neurons.

norepinephrine: both a hormone and neurotransmitter; plays a role in attentiveness, emotions, sleep, dreaming, learning, and mood disorders.

parasympathetic nervous system: acts in complementary manner to the sympathetic nervous system as part of the autonomic nervous system, calming the system back to homeostatic baseline resting state.

serotonin: one of the major neurotransmitters; plays a role in mood, social behavior, appetite, sleep, memory and sexual function.

sympathetic nervous system: serves as the mechanism for the “fight or flight” response by stimulating breathing and heart rate, and regulating other organ functions to create a state of arousal; part of the autonomic nervous system, complemented by the parasympathetic nervous system.