In tobacco smoke, nicotine "rides" on small particles of tar. When the smoke with this nicotine/tar mixture gets to the lungs. the nicotine is absorbed quickly - nicotine reaches the brain about eight seconds after the smoke is inhaled. American cigarettes contain about 9 mg of nicotine, but because much of the nicotine is burned off, a smoker gets about 1 mg of nicotine in every cigarette.
I bet I got more than 1mg. I was a deep smoker.