Nicotine is one of the primary components in tobacco, and it is a highly addictive drug. When tobacco smoke is inhaled, nicotine is absorbed into the blood stream and can affect the brain within seconds. As a person continues to smoke, the brain builds up a tolerance for nicotine. This develops into a powerful addiction, which can be as difficult to break as addiction to cocaine or heroin.
Dopamine
Dopamine, which is a neurotransmitter in the brain, produces feelings of pleasure and arousal. Nicotine temporarily raises the dopamine levels in the brain, causing the smoker to rely on cigarettes in order to maintain this sensation of pleasure.
Endorphins
Nicotine causes the brain to produce more endorphins, which help to relieve both physical and emotional pain. This helps smokers feel a decrease in stress, and therefore strengthens their addiction to nicotine.
