Nicotine is a colorless and odorless alkaloid that is found in tobacco plants. When tobacco is smoked, nicotine is absorbed into the bloodstream through the lungs. Nicotine can also be absorbed through the skin or mucous membranes.
Once in the bloodstream, nicotine travels to the brain where it binds to receptors in the brain's reward system. This binding triggers the release of dopamine, a neurotransmitter that is associated with pleasure and reward. Nicotine also increases the heart rate and blood pressure, and can lead to addiction.
