Nicotine works on the brain and other parts of the nervous system. While a person is smoking, nicotine reaches the brain faster than drugs that enter the body directly through the veins. When smokers breathe in smoke, they draw nicotine into their lungs. Then, their bloodstream picks it up and it is quickly pumped by the heart right to the brain. Within just seven seconds the nicotine reaches the brain.
Some nicotine goes to other parts of the body.
And if a woman is pregnant, this burst of nicotine also reaches the fetus through connecting blood vessels. In large amounts, addictive drugs like nicotine, heroin and cocaine are poisons. For example, nicotine has been used to kill insects. Nicotine makes the heart beat faster, increases the breathing rate and causes the body to use more oxygen. Nicotine causes other changes in the circulatory system, too.