Forms: cigarettes, cigars, hookah, chew, stuff, dipping tobacco, dissolvable tobacco. Lung cancer, chronic obstructive pulmonary disease: emphysema, heart disease greatest causes of death associated with tobacco use. Tar- particles from tobacco that contains nicotine and other chemicals. Smoking- most common administration; matters adheres to tissues in mouth, nose, throat and lungs; when exhaled, adheres to skin. Freebase form- best absorbs thru mucous membranes in mouth. In the liver: it is metabolized by hepatic enzymes and produces active metabolite cotinine. Ach and nicotine cause receptors to open. Receptors desensitize: channels close and can"t be opened even when agonist is bound. Nicotinic-receptor agonists produce functional antagonism nicotine causes these receptors to have longer inactivated state. Improves information processing by shortening times to detect stimuli, and attention. Nicotine improved reaction times in stroop test. Nontobacco users- negative effects: nausea, disequilibrium, jitterness, tension and confusion. Chronic users- positive effects: vigor, arousal, reduced fatigue, positive mood.