Nicotine, a chemical found in cigarettes, is one of the most toxic and addictive alkaloid poisons found in the tobacco plant. Alkaloids react with acids to form salts. These salts may be used in medicines. Nicotine is used in gums and transdermal (skin) patches to be used in smoking cessation therapy. The rationale is to reduce withdrawal symptoms that accompany quitting smoking. Nicotine has both a stimulant and depressant effect on the body.
In the cardiovascular system, nicotine acts as a stimulant. Nicotine causes vasoconstriction, which is narrowing of blood vessels. Billie Ann Wilson, Ph.D., Margaret Shannon, Ph.D., and Kelly Shields Pharm.D., authors of the 2010 Pearson Nurse's Drug Guide, explain that the vasoconstrictive effects of nicotine cause hypertension, which is elevated blood pressure. In addition to hypertension, vasoconstriction decreases blood flow to the heart. This can lead to chest pain and increase the risk of myocardial infarction or heart attack.
Increased Cardiac Output
Nicotine acts as a chronotropic agent. This means it increases the heart rate. An increased heart rate increases cardiac output which is the amount of blood pumped to the body every minute. A higher cardiac output means a greater workload is placed on the heart.
Nicotine has a stimulant effect on the heart. Because of this, people who consume nicotine are at risk for palpitations, a rapid heart rate, and arrhythmias. Arrhythmias are irregular heart rhythms. Some arrhythmias can be lethal.
Nicotine causes an increased respiratory rate as well as an increase in production of respiratory secretions. Although respiratory stimulation occurs at low dosing, overdose can cause paralysis of the respiratory system, resulting in respiratory failure and death.
Increased Metabolic Rate
The National Institute on Drug abuse reports that nicotine causes an increased metabolism. Smokers typically weigh 6 to 9 pounds less than nonsmokers. This effect has been correlated with the finding that smokers who quit smoking tend to gain 6 to 9 pounds.
Nicotine has a depressant effect on appetite. Anorexia, or loss of appetite, is common among smokers and is part of the reason for the typical lower weight found among smokers. Anorexia can cause constipation and indigestion. However, peristalsis, which is the normal wavelike contractions of the intestine that propels contents through the gastrointestinal tract, is stimulated from nicotine. Increased peristalsis causes diarrhea.
One of the effects of nicotine on the body is increased reflexes. The cholinergic effects of nicotine affect nerve impulses. The speed of finger tapping has been shown to increase with nicotine use.
Nicotine has been found to improve recognition memory. However, the improvement is modest at best and the risks of nicotine use do not outweigh this benefit.