The first time cigarette smokers smoked cigarettes there were only a few cholinergic receptors available because the natural action of acetylcholine only needs the normal amount of receptors provided by nature to do its job. However, the increase concentration of nicotine available caused the normal amounts of cholinergic receptors to become desensitized to the presence of the increased number of nicotine in the cholinergic receptors. This desensitization causes the production or growth and development of more cholinergic receptors. These extra cholinergic receptors will soon become desensitized from the excess nicotine available. Such processes occur until equilibrium is reached. Equilibrium is reached when cigarette smokers decide on the amount of cigarettes they will consume or smoke in a given day. At this time, a fixed amount of receptors will be available for the addiction to continue. Smokers will normally say they smoke one or two packs per day. They said so because of the amount of receptors available to accommodate two packs of cigarettes in a day.