Final answer:
The nurse's observation of a flight-or-fight response in a client is linked to elevated norepinephrine levels, a key neurotransmitter in the body's sympathetic nervous system response.
Step-by-step explanation:
The restless, agitated client that the nurse concludes is manifesting a flight-or-fight response is likely experiencing elevated levels of the neurotransmitter norepinephrine. During a fight-or-flight response, the adrenal medulla secretes catecholamines, which include epinephrine and norepinephrine(NE), into the bloodstream. These neurotransmitters are associated with the body's sympathetic nervous system response, which prepares the body to either fight or flee from a perceived threat. Norepinephrine acts on various receptors and can lead to increased heart rate and blood flow to muscles, dilated airways, and decreased blood flow to non-essential systems, thus having a prominent role in the physiological changes accompanying the fight-or-flight response.