![]() ![]() The euphoria induced serves as a re-inforcer for its use. This brain reward system is a common pathway for pleasurable activities in most drugs of addiction. ![]() This bolus of nicotine activates the brain-reward system by increasing dopamine release as it is a potent psycho-active drug. Blood nicotine levels rise very rapidly and peak at the time cigarette is extinguished and steep decline occurs until the next cigarette is smoked. Absorption leads to a marked increase in arterial nicotine level within 15 seconds. About 90% of nicotine present in inhaled smoke is absorbed. These droplets, less than 1000 of a millimeter across, can reach the smallest alveoli in the lungs. Nicotine remains dissolved in the moisture of the tobacco leaf as a water soluble salt, but in a burning cigarette it volatilizes and remains suspended on minute droplets of tar as free nicotine. Of the 4000 chemicals identified in tobacco smoke, nicotine is the pharmacological agent of prime importance, which is highly toxic and potentially lethal alkaloid (1-methyl-2- pyrrolidine), responsible for a number of pathophysiological changes in the body. From the incandescent tip of a lighted cigarette, burning at a temperature of 800☌, the smoker with each puff draws into his mouth a hot potpourri of gases and many sized particles. ![]()
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