Final answer:
The nurse should explain that nicotine makes a patient feel calm because it affects the brain's pleasure system, but it also activates the sympathetic nervous system, increasing cardiovascular risks.
Step-by-step explanation:
The nurse's best response regarding why nicotine makes a patient feel calm even though it's harmful is: "Nicotine acts on the pleasure system in the brain, which lessens feelings of aggression." This statement explains that nicotine, delivered through smoking, stimulates receptors that affect the autonomic nervous system, leading to both stimulating and relaxing sensations. It is the stimulation of the sympathetic nervous system that leads to increased heart rate, blood pressure, and is associated with a rise in cardiovascular risk.
Nicotine binds to nicotinic acetylcholine receptors and affects various neurotransmitters that are involved in arousal and reward mechanisms. The autonomic control of the heart is complex because cardiac muscle is intrinsically active and modulated by autonomic inputs, leading to competing signals that can cause arrhythmias. Meanwhile, systemic blood pressure is predominantly regulated by the sympathetic nervous system, which nicotine activates, causing a rise in blood pressure.
In summary, while nicotine, through its interaction with receptors, can trigger a sense of calm by influencing the brain's pleasure system, it simultaneously poses a significant health risk, especially in terms of cardiovascular disease.