More than 46 million adults in the United States smoke
cigarettes, cigars, or pipes, and a few million use snuff or
chewing tobacco. Although 70% of smokers say they'd like to stop,
nicotine is so addictive that only 3% successfully quit each
Smoking sends nicotine straight to the lungs, where it is
absorbed by oxygenated blood, delivered to the heart, and pumped
into the arteries and to the brain. The nicotine in snuff and
chewing tobacco, which is absorbed mainly through the mucous
membranes of the mouth, reaches the brain more slowly, but
constant use maintains a steady level in the blood and
Once in the brain, nicotine triggers the release of the
neurotransmitter dopamine in the nucleus accumbens, which is the
brain's reward and motivation center. Each hit of nicotine
produces pleasurable feelings. But as it gets washed out of the
body, the feelings of pleasure are replaced by uncomfortable
symptoms of withdrawal — trouble concentrating, nervousness,
headaches, increased appetite, dizziness, irritability, anxiety,
depression, and sleeping problems. This prompts most users to
reach for more tobacco.
For people who want to stop using tobacco, two hurdles must be
jumped: overcoming the physical addiction to nicotine and
breaking the psychological habit.
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