Nicotine

==== Heather Lake and David Sperry .... mitch mountain ====


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=**Nicotine **   =

====__ History of nicotine __ It has been chewed, sniffed, and smoked. Today it is most commonly used in the form of cigarettes. Tobacco comes from the plant //nicotiana tabacum//. The reason tobacco is used by so many people is because it contains a powerful drug known as nicotine which is not only addictive, but gives you a pleasurable sensation. The 'habit' itself is also addictive. ====

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__What is nicotine?__ =====

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 Nicotine is the drug that tobacco leaves. Whether someone smokes, chews, or sniffs tobacco, he or she is delivering nicotine to the brain. <span style="FONT-SIZE: 12pt; COLOR: red; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif">Nicotine is an addictive drug. It causes changes in the brain that make people want to use it more and more. ===== <span style="FONT-SIZE: 12pt; COLOR: red; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif">

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<span style="FONT-SIZE: 12pt; COLOR: red; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif"> <span style="FONT-SIZE: 12pt; COLOR: red; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif">  =====

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<span style="FONT-SIZE: 12pt; COLOR: red; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif"> <span style="FONT-SIZE: 12pt; COLOR: #0f0000; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif">__How does it effect the central nervous system?__  =====

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<span style="FONT-SIZE: 12pt; COLOR: #0f0000; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif"> <span style="FONT-SIZE: 12pt; COLOR: red; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif">Cigarette smoke contains thousands of chemicals, many are responsible for its powerful addictiveness. When tobacco is smoked, nicotine is absorbed by the lungs and quickly transported into the bloodstream, where it is circulated through the brain. This all happens very rapidly, so fast in fact that, nicotine reaches the brain within 8 seconds after someone inhales tobacco smoke. Nicotine can also enter the bloodstream through the mucous membranes that line the mouth, if chewed or nose and even through the skin. Nicotine is a deadly toxin, if a single pinhead-sized drop of liquid nicotine was put into your bloodstream, it would be fatal. In general, small doses of nicotine have a stimulating action on the <span style="FONT-SIZE: 12pt; COLOR: blue; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'">[|central nervous system] <span style="FONT-FAMILY: Arial, Helvetica, sans-serif"><span style="FONT-SIZE: 12pt; COLOR: red; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'">whereas large doses depress. However, studies of the central nervous actions of nicotine have not yet fully established confident correlations of the action of this drug with central levels. For this reason it has not been possible to consider its actions on the basis of a strictly neuroanatomical outline. Nicotine makes the smoker addictive because nicotine affects the chemistry of the brain and central nervous system, it can affect the mood and nature of the smoker. Nicotine acts as a stimulant on the central nervous system and also has many metabolic affects. It increases the metabolic rate, raises blood pressure, changes muscle tension and affects certain brain chemicals and hormones. These and other metabolic changes create a pleasurable sensation in the smoker that is felt as relaxation. This "pleasure-sensation" is one of the elements that makes tobacco so addictive. Once you become addicted your body depends on the presence of nicotine <span style="FONT-SIZE: 12pt; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'">. ===== <span style="FONT-SIZE: 12pt; LINE-HEIGHT: 115%; FONT-FAMILY: 'Arial','sans-serif'; mso-fareast-font-family: 'Times New Roman'"><span style="FONT-FAMILY: Arial, Helvetica, sans-serif">

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Your brain is the key player in nicotine's action. Like a computer, your brain processes, stores and uses information. In a computer, information travels in the form of electricity moving through wires; information transfer is a binary process, with switches being either "on" or "off." In your brain, [|neurons] are the cells that transfer and integrate information. Each neuron has thousands of inputs from other neurons throughout the brain. Each of these signals is included in the calculation of whether or not the neuron will pass the signal it receives on to other neurons in the pathway. =====

[[image:http://static.howstuffworks.com/gif/nicotine3.jpg align="center"]]
==== **(A synapse is the site where two neurons come into contact. The presynaptic neuron releases a neurotransmitter, which binds to receptors on the postsynaptic cell. This allows signals to be transmitted from neuron to neuron in the brain.)** ====

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While signals are conducted through individual neurons as electric current, communication between neurons is mediated by chemical messengers, called [|neurotransmitters.] Neurotransmitters traverse the physical space between two neurons and bind to special protein receptors on the postsynaptic cell. Once bound, these receptors set in motion physiological changes within the neuron that allow it to send the signal on down the line. =====

Each neurotransmitter has its own specific family of receptors. Nicotine works by docking to a subset of receptors that bind the neurotransmitter [|acetylcholine.] Acetylcholine is the neurotransmitter that (depending on what region of the brain a neuron is in): > > > (**Acetylcholine is released from one neuron and binds to receptors on adjacent neurons.)**
 * Delivers signals from your brain to your muscles
 * Controls basic functions like your energy level, the beating of your heart and how you breathe
 * Acts as a "traffic cop" overseeing the flow of information in your brain
 * Plays a role in learning and memory

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Like acetylcholine, nicotine leads to a burst of receptor activity. However, unlike acetylcholine, nicotine is not regulated by your body. While neurons typically release small amounts of acetylcholine in a regulated manner, nicotine activates cholinergic neurons (which mainly use acetylcholine to communicate to other neurons) in many different regions throughout your brain simultaneously. =====

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Nicotine activates the same reward pathways in the brain that other drugs of abuse such as cocaine or amphetamines do, although to a lesser degree. Research has shown that nicotine increases the level of dopamine in the brain, a [|neurotransmitter] that is responsible for feelings of pleasure and well-being. The acute effects of nicotine wear off within minutes, so people must continue dosing themselves frequently throughout the day to maintain the pleasurable effects of nicotine and to prevent withdrawal symptoms. ======