A patient has anxiety, increased heart rate, and fear. The nurse would suspect the presence of a high concentration of which neurotransmitter?

A) GABA
B) Histamine
C) Acetylcholine
D) Norepinephrine

Norepinephrine is the neurotransmitter associated with sympathetic nervous system stimulation, preparing the individual for the "fight-or-flight" response. GABA is a mediator of anxiety level. A high concentration of histamine is associated with an inflammatory response. A high concentration of acetylcholine is associated with parasympathetic nervous system stimulation.