A fearful patient has an increased heart rate and blood pressure. The nurse suspects increased activity of which neurotransmitter?

Choice A reason: GABA is an inhibitory neurotransmitter that reduces neuronal activity, promoting calm. In fear, the sympathetic nervous system activates, increasing heart rate and blood pressure, driven by excitatory neurotransmitters, not GABA, which would counteract these effects, making this choice incorrect. Choice B reason: Norepinephrine, a catecholamine, activates the sympathetic nervous system during fear, increasing heart rate and blood pressure via the fight-or-flight response. Its heightened activity in stress aligns with the patient’s symptoms, making this the correct neurotransmitter choice. Choice C reason: Histamine regulates arousal and allergic responses but is not primarily responsible for cardiovascular changes in fear. Its role in the brain is less direct than norepinephrine in driving sympathetic activation, making this choice incorrect for the symptoms described. Choice D reason: Serotonin modulates mood and anxiety but does not directly cause acute cardiovascular changes like increased heart rate and blood pressure in fear. These are driven by norepinephrine’s sympathetic activation, making serotonin an incorrect choice for this scenario.