Nicotine, a naturally occurring alkaloid found in tobacco leaves, most commonly enters the human body as cigarette smoke. Each cigarette contains 10mg to 20mg of nicotine, but the body absorbs only about 1mg through smoke. Nevertheless, that single milligram has a powerful effect on human blood vessels.
Within minutes after you inhale tobacco smoke, nicotine begins to change your body chemistry. Hormones, including adrenaline, flood the bloodstream. The adrenaline stimulates the body's вЂњfight or flightвЂќ response by raising blood pressure, increasing heart rate and speeding up breathing. Nicotine raises blood pressure by causing the walls of blood vessels to constrict.
By constricting the blood vessel walls to raise blood pressure, nicotine also decreases the amount of blood that can pass through the vessels. Impaired circulation means that less oxygenated blood can reach every part of the body, which can trigger a wide range of medical problems. In some cases, nicotine has been proven to stimulate the growth of new blood vessels. This may be the body's way of attempting to restore circulation. But the new blood supply carries its own long-term dangers, discussed below.
Blood vessels in which build-up of arterial plaque already limits blood flow are especially vulnerable to the effects of nicotine. The further constriction caused by nicotine may be enough to trigger cardiac arrest. Nicotine also limits circulation in blood vessels in the brain, making those vessels more susceptible to clots or leaks, which can lead to a stroke. Nicotine increases stress on weakened areas of the blood vessel walls, which can then bulge or rupture, causing aneurysms. Decreased circulation also can lead to erectile dysfunction.
The chronic irritation of nicotine can make blood vessels more susceptible to plaque over time, a condition known as atherosclerosis or вЂњhardening of the arteries.вЂќ By stimulating new blood vessels to grow, especially at areas of inflammation such as plaque deposits, nicotine may accelerate the growth of cancerous tumors. Cigarette smoking has been proven to worsen lung and breast cancers. One reason for this is nicotine's effect on blood vessels.
Nicotine causes particular dangers in pregnant women. The mother's blood carries oxygen and nutrients to the baby, and carries away the baby's physical waste products. Nicotine's constricting effect on blood vessels slows both of these processes. Smoking mothers have a greater risk of miscarriage. If the pregnancy continues, they're more likely to suffer prematurely detached placentas, a potentially fatal condition to the baby. The risk of detached placenta increases 20 percent for each half pack of cigarettes smoked daily. Successful pregnancies of smoking mothers are far more likely to produce low birth-weight babies, who may suffer a myriad of medical problems. Children born to mothers who smoked during pregnancy have a greater likelihood of mental and physical developmental problems, death from sudden infant death syndrome, and hyperactivity.
Research has shown that an individual's circulation begins to improve within 2 weeks after quitting smoking. The blood vessels regain most of their normal function within 3 months.