Changes

== Nicotine ==

== Nicotine ==

Nicotine is an alkaloid in tobacco that is responsible for the addictive nature of cigarette smoking and other tobacco use.  Nicotine reaches the brain about seven seconds after it is inhaled in cigarette smoke, and stimulates the release of a number of [[neurotransmitters]], including [[dopamine]], [[norepinephrine]], and [[acetylcholine]].  The increased availability of these chemicals in the brain leads to feelings of pleasure and mild euphoria, as well as increased alertness and concentration.  The half-life of nicotine is approximately two hours.

Nicotine is an alkaloid in tobacco that is responsible for the addictive nature of cigarette smoking and other tobacco use.  Regular nicotine consumption leads to [[tolerance]] (i.e., higher doses are required to achieve the same effect), and [[withdrawal]] symptoms (e.g., irritability, restlessness, nicotine cravings) occur when use is discontinued.  Intake elicits acute increases in heart rate and blood pressure, as well as respiratory rate.  Nicotine reaches the brain about seven seconds after it is inhaled in cigarette smoke, and stimulates the release of a number of [[neurotransmitters]], including [[dopamine]], [[norepinephrine]], [[serotonin]], and [[acetylcholine]].  The increased availability of these chemicals in the brain leads to feelings of pleasure and mild euphoria, as well as increased alertness and concentration.  The half-life of nicotine is approximately two hours.

== Tobacco Products ==

== Tobacco Products ==