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Kamis, 29 November 2012

NICOTINE






Nicotine, C 10 H 14 N 2 , is a highly toxic, pale yellow alkaloid produced in tobacco plants in response to leaf damage. Nicotine is synthesized in the roots of tobacco plants in response to hormones released by damaged tissue, and it is then carried to the leaves, where it is stored in concentrations of between 2 percent and 8 percent by weight. Nicotine is used commercially as an insecticide (it is one of the few poisons to which insects have not become resistant). Tobacco smoke contains nicotine, believed to be the active (and addictive) ingredient.
Mayan peoples of South America used tobacco for recreational and ceremonial, as well as medicinal, purposes. Mayan sculptures depict high-ranking persons smoking cigars and priests blowing tobacco smoke over human sacrifices. By the time of the arrival of Christopher Columbus in the New World, tobacco use had spread throughout both North America and South America. Early accounts by European explorers describe Native Americans carrying glowing sticks from which they inhaled, and many pipes are found among Native American artifacts. Tobacco was often chewed by Native Americans; the juice was dropped into eyes to improve night vision and applied to skin as an agent having antiseptic properties.
The men who accompanied Columbus encountered many users of tobacco, but early European explorers showed little interest in the plant until they acquired an awareness that it might be used to treat diseases. Europeans at first forbade tobacco use, but tobacco gradually gained a reputation among court physicians as a medicine. For many Europeans, tobacco was suddenly a valuable New World commodity.
Nicotine is the active ingredient of tobacco. Nicotine is soluble in water and in nonpolar solvents. It can be absorbed by the body from smoke that has been taken into the lungs, or through the skin. It rapidly crosses the blood-brain barrier, appearing in brain tissue minutes after its absorption into capillaries lining the alveoli of the lungs. The presence of nicotine in the body stimulates nicotinic-cholinergic receptors of the nervous system, resulting in increased attention span, increased heart rate and blood pressure, and increases in the concentrations of some hormones. Habitual users have a feeling of well-being after intake of nicotine, ascribed to the increased concentrations of dopamine in the brain. The increased metabolic rate that is associated with nicotine use may be what is in back of the common belief that it is easier to lose weight when using nicotine.
Nicotinic-cholinergic receptors that are part of the autonomic nervous system may be stimulated at low concentrations of nicotine, but blocked at higher concentrations. The repeated use of nicotine-containing products (which includes chewing tobacco, chewing nicotine-containing gum, or the use of therapeutic patches that release nicotine for skin absorption) promotes the formation of (new) nicotinic-cholinergic receptors. The tolerance and eventual addiction that go along with repeated use may result in increased craving for nicotine.
Many environmentally hazardous substances, such as asbestos and radon, are much more hazardous when they become mixed with cigarette smoke, probably because the particulate matter in smoke in the atmosphere may adsorb these dangerous substances and carry them into the alveoli of lungs. Many cancers may be caused by substances or materials associated with nicotine use, such as tobacco smoke or the tobacco plant itself (as in chewing tobacco). Nicotine itself, although not known to cause cancer directly, causes proliferation of both healthy and neoplastic cells, and may further the development of cancer by stimulating angiogenesis (the growth of new blood vessels) and thus providing cancerous tissues with increased blood supplies. The effect of nicotine on cell growth is especially strong in tissue environments having low concentrations of carbon dioxide, for example, in damaged lungs; thus, the effect would be greater in persons whose breathing was already impaired. Nicotine's stimulation of cell growth may account for the observation that atherosclerotic plaques (which are intracellular accumulations of lipids ) grow more rapidly in the presence of this alkaloid substance. This effect may actually become the basis of medical treatments intended to improve blood flow to tissues damaged by atherosclerosis.
Single exposure to nicotine in quantities as small as 50 mg (0.0018 oz) may result in vomiting and seizures; the average cigarette yields about 3 mg(0.00011 oz). As nicotine can be absorbed through skin, accidental exposures in persons working with nicotine-containing pesticide preparations may be fatal. Extracts of chewing tobacco are effective insecticides; commercial insecticide products contain much higher amounts of nicotine than products intended for human consumption.
Biosynthesis Of Nicotine

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Levels of nicotine ON TOBACCO

Nicotine in tobacco as a central nervous system stimulant, tobacco as a major component in cigarettes is a stimulant of the central nervous system. Tobacco made up of thousands of components, wherein the main component consists of nicotine, tar and carbon monoxide. Nicotine quickly enter the brain so a person smokes. Levels of nicotine that is inhaled to be capable of causing death if the levels are over 30 mg. Each cigarette contains nicotine average 0.1-1.2 mg nicotine. Of these, the levels of nicotine in the blood circulation is 25%, but a small amount is able to reach the brain within 15 seconds Tar is not a single substance, composed of hundreds of chemicals dark and sticky, and classified as a poison maker of cancer. Often, many do not include the tobacco tar and nicotine in cigarette packaging production. For example, Sampoerna A Mild is claimed as a cigarette lighter, has a level of 1.5 mg tar per stem. Carbon monoxide is a poison that expel oxygen from binding to hemoglobin in red blood grains. CO bonds with hemoglobin (COHb) will make HB can not break the bonds CO and consequently function as an oxygen-carrying hemoglobin decreased function and this causes the heart work more.
Nicotine as a substance most widely associated with addiction to cigarettes received by the nicotinic acetylcholine receptor-adrenergic pathway that then to make smokers feel more calm, pleasure, stimulate the dopaminergic system, and feel the power of thought more brilliant. While in the adrenergic pathway, this substance will turn on the adrenergic system that secrete the neurotransmitter serotonin. Increased incidence of serotonin is what causes the stimulation of pleasure to find another cigarette. The process is no different from burning cigarettes different from the process of burning other solid materials. Cigarettes are made from dried tobacco leaves, paper, flavorings substances that can be formed by the elements carbon (C), the element hydrogen (H), the element oxygen (O), the elements Nitrogen (N), the element sulfur (S) and elements Another small amounts.  Cigarette overall chemistry can be formulated as CvHwOtNySzSi. This will cause dangerous reactions cigarettes for health include:

a) Reaction cigarette with oxygen to form compounds such as CO2, H2O, NOx, SOx, and CO. This reaction is called combustion reactions that occur at high temperatures are above 800 degrees Celsius which occurs at the end of a cigarette or surface in contact with air.
The process of burning cigarettes can be explained by chemical reactions CvHwOtNySzSi + + O2 combustion to CO2 above 800 C + + NOx SOx + SiO2 (ash).

b) The reaction solution to the chemical structure of chemical compounds cigarette chemicals. The reaction is due to the high heating and absence of oxygen in this reaction. This reaction known as pyrolysis reaction. Pyrolysis occurs at lower combustion than 800 degrees Celsius (about 400-800 degrees Celsius). Characteristic of the pyrolysis reaction is the formation of thousands of chemical compounds that are complex. This process can be explained by the chemical reaction combustion CvHwOtNySzSi + 400-800 C into other chemical compounds (3000 complex molecules). Although the pyrolysis reaction is not dominant in the process of smoking, but many belonging to the compounds produced toxic compounds that have the ability to diffuse in the blood. Pyrolysis reaction is a reaction that is the most dangerous in the process of smoking. Actually this can be burnt pyrolysis products when the product through high temperature and sufficient oxygen, which did not occur in this process because of the inhaled smoke and gas products in the area of ​​400-800 degrees Celsius temperatures flow directly toward the mouth of the temperature around 37 degrees Celsius.

c) The reaction of the evaporation of water vapor and nicotine. The reaction takes place at a temperature of 100-400 degrees Celsius where the nicotine is vaporized at this temperature region no chance with a high temperature and does not undergo combustion process. Terkondensasinya nicotine vapor in the gas depends on the temperature, the concentration of nicotine vapor in the gas and the geometry of the channels through which the gas. If the temperature is less than 100 degrees Celsius, the nicotine is condensing, so that before the gas enters the mouth, nicotine condensation has occurred and the gas enters the lungs still contain these substances, which in the lungs, nicotine will experience condensation back.