Final answer:
Nicotine stimulates both sympathetic and parasympathetic ganglia in the body, but its effects on the cardiovascular system are different. It increases blood pressure and can cause arrhythmias, which are risk factors for heart disease.
Step-by-step explanation:
Nicotine, when introduced into the body, stimulates both sympathetic and parasympathetic ganglia at the preganglionic fiber synapse. While the competing input from the two postganglionic fibers cancel each other out in most organ systems, they have different effects on the cardiovascular system. Since there is essentially no parasympathetic influence on blood pressure, the sympathetic input is increased by nicotine, causing an increase in blood pressure. Additionally, the contradictory signals from the autonomic system alter the regularity of the heart rate and can cause arrhythmias, both of which are risk factors for heart disease.