August 07, 2007

Tobacco Trouble ?

cigarette smokeFor centuries this substance, obtained from the plant Nicotiana tabacum has entertained (or rather haunted) the human race. After Colombus's introduction of this habit into the new world, a tobacco epidemic has gripped the entire world. The addictive ingredient in tobacco is mostly nicotine, while its adverse effects on human bodies are largely attributable to its tar content. When smoked, about 4,000 different molecules are released and this includes the radioactive substance Polonium 210.

Not only the active smoker inhales it but also the 'sidestream smoke' it generates, makes passive smoking a reality. Nicotine is then rapidly absorbed from the lungs. The vast capillary networks surrounding the pulmonary alveoli aid its absorption directly into the blood stream. The onset of its action is very quick, since it takes only a few seconds to pass across the blood brain barrier. The blood-brain barrier acts as a frontier of defense in the brain, against many molecules thus protecting the brain.

Nicotine then liberates a long list of neurotransmitters including, noradrenaline, adrenaline (they make the heart race, pump more blood into the circulation, makes you alert, increases the blood glucose level and many related actions responsible for 'fight or flight reaction'), beta endorphin (a pleasure chemical in the brain, which binds to the opioid/morphine receptors), dopamine (a substance released from the 'reward center' of the brain ) and many others. These substances make smokers feel alert, cool and all the effects a smoker feels. These are the same chemicals that cause the serious cravings when one tries to kick the habit.

Nicotine, in addition, stimulates nicotinic cholinergic receptors in small doses, but depresses them in larger amounts. Tobacco causes a plethora of diseases. Cardiovascular diseases including peripheral arterial diseases; pulmonary diseases like emphysema, chronic bronchitis and cancers are just a few of them. It also decreases the sperm count, and even causes impotency (due to its vasoconstricting action).

But not all of us know that it guards against some diseases too. The frequency of ulcerative colitis, Alzheimer's disease, Parkinson's disease, and even breast cancers (in women harboring the BRCA gene =BReast CAncer) are statistically less in smokers than in non smokers. But the risks far outweigh the benefits it offers. Hence, kicking the habit is a more sensible option than to carry on smoking.
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