Substances that damage the circulatory and repiratory system:

Nicotine: one of the most damaging substances to the respiratory and circulatory system is the nicotine. Nicotine is one of the substances that smokers get from cigarettes. Smokers need some amount of nicotine, daily, to feel normal and to control their mood. And, when they continue smoking, they need more and more nicotine, so each time they consume more. Basically what nicotine does is to make you consume it more each time you smoke. Also, it hardens your arteries, which make you increase your level of bad cholesterol.
Tar: It contains cancer-causing substances. Tar is brown and stains teeth, fingernails and lungs tissue.
Carbon monoxide: What carbon monoxide cause is that less oxigen reaches the brain, heart, mussels and other organs.
Hidrogen cyanide: the lungs clean themselfs with little hairs. this stops the lungs clearence system from working properly.

Free radicals: They react with cholesterol, and make easier to build-up the artery walls.
http://www.youtube.com/watch?v=FeM744Z2V4A&feature=related