Nicotine
"If it were not for the nicotine in tobacco smoke, people would be little more inclined to smoke than they are to blow bubbles or to light sparklers."
So what is nicotine, and how does it effect the human body and produce this tremendous dependency? Nicotine is poisonous alkaloid, which at high dosages has been used in everything from insecticides to darts designed to bring down elephants.
Vegetable derivatives like morphine, nicotine and cocaine are potent drugs. At high doses, nicotine can cause high blood pressure, distress in the respiratory and gastrointestinal systems, and an increase in susceptibility to seizures and hypothermia. Inhaled nicotine directly effects the brain and the circulatory system. Studies have shown that a smoker's first cigarette of the day can increase his or her heart rate by as much as 10 to 20 beats a minute.
First isolated as a chemical compound in 1828, nicotine is a clear, naturally occurring liquid that turns brown when burned and smells like tobacco when exposed to air. It is found in several species of plants, including tobacco and, perhaps surprisingly, in tomatoes, potatoes, and eggplant (though in extremely low quantities that are pharmacologically insignificant for humans). In tobacco, the highest concentration of nicotine appears in the plant's topmost leaves.
As simple as it looks, the cigarette is a highly engineered nicotine-delivery device. For instance, when tobacco researchers found that much of the nicotine in a cigarette wasn't released when burned but rather remained chemically bound within the tobacco leaf, they began adding substances such as ammonia to cigarette tobacco to release more nicotine. Ammonia helps keep nicotine in its basic form, which is more readily vaporized by the intense heat of the burning cigarette than the acidic form. Most cigarettes for sale in the U.S. today contain 10 milligrams or more of nicotine. By inhaling smoke from a lighted cigarette, the average smoker takes in one to two milligrams of vaporized nicotine per cigarette.
When a smoker puffs on a lighted cigarette, smoke, including vaporized nicotine, is drawn into the mouth. The skin and mucosal lining of the mouth absorb some nicotine, but the remainder flows straight down into the lungs, where it easily diffuses into the blood vessels lining the lung walls. The blood vessels carry the nicotine to the heart, which then pumps it directly to the brain.
Scientists have found that a smoked substance reaches the brain more quickly than one swallowed, snorted (such as cocaine powder), or even injected. Indeed, a nicotine molecule inhaled in smoke will reach the brain within 10 seconds. The nicotine travels through blood vessels, which branch out into capillaries within the brain. Capillaries normally carry nutrients, but they readily accommodate nicotine molecules as well. Once inside the brain, nicotine, like most addictive drugs, triggers the release of chemicals associated with euphoria and pleasure.
Once in the bloodstream, nicotine molecules easily diffuses through capillary walls where they migrate to the spaces surrounding your neurons. Neurons are gangly cells that transmit nerve impulses throughout the nervous system. They release chemical messengers known as neurotransmitters. Like nicotine molecules, the neurotransmitters drift into the so-called synaptic space between neurons, ready to latch onto the receiving neuron and thus deliver a chemical "message" that triggers an electrical impulse.
An accomplished mimic, nicotine competes with neurotransmitters to bind to the body's receptors and in doing so opens ion channels that let sodium ions into the cells. This allows a much larger current to spread across the membrane. This bigger current causes increased electrical impulses to travel along certain neurons. With repeated smoking, the neurons adapt to this increased electrical activity, and the smoker becomes dependent upon the nicotine.
Extracted from:-
Nicotine the Addiction
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The nicotine timeline below shows the age and knowledge of this addictive substance. It's interesting to note that it was first synthesized over 100 years ago.
1527:- Tobacco recorded as addictive by Bartolomé de Las Casas. |
| 1805-1807:- CERIOLI isolates nicotine, the "essential oil" or "essence of tobacco" |
| 1809:- Louis Nicolas Vanquelin isolates nicotine from tobacco smoke. |
| 1822:- Hermbstdt isolates nicotine and calls the causa efficiens of nicotianas Nicotianin. |
| 1828:- Heidelberg students Ludwig Reimann and Wilhelm Heinrich Posselt are credited with first isolating nicotine in a pure form; write exhaustive dissertations on the pharmacology of nicotine, concluding it is a "dangerous poison." |
| 1843:- The correct molecular formula of nicotine is established. |
| 1889:- Nicotine and nerve cells reported on. Langley and Dickinson publish landmark studies on the effects of nicotine on the ganglia; they hypothesize that there are receptors and transmitters that respond to stimulation by specific chemicals. |
| 1893:- Pure nicotine is first synthesized by Pictet and Crepieux. |
| 1904:- The first US laboratory synthesis of nicotine is reported. |
| 1942:- British researcher L.M. Johnston successfully substituted nicotine injections for smoking. |
1967:- Federal Trade Commission releases the first tar and nicotine report.
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