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Tobacco was first found and cultivated, perhaps as early as 6000 B.C. and for
thousands of years, people have smoked or chewed the leaves of the tobacco
plant. Following the discovery and
colonization of North and South America, the tobacco plant was exported widely,
to continental Europe and the rest of the world.
Smoking or chewing tobacco makes you feel good, even
mildly euphoric. While there are thousands of chemicals in the tobacco plant
(not to mention those added by cigarette manufacturers), one, nicotine, produces
all the good feelings that draws you back for another cigarette.
Nicotine is a naturally occurring liquid alkaloid.
Alkaloids are an organic compound made out of carbon, hydrogen, nitrogen and
sometimes oxygen. These chemicals have potent effects on your body. Another
alkaloid is caffeine. A
toxin to your body.
Nicotine normally makes up about 5 percent of a tobacco
plant, by weight. Cigarettes contain 8 to 20 milligrams (mg) of nicotine
(depending on the brand), but only approximately 1 mg is actually absorbed by
your body when you smoke a cigarette
As with most addictive substances, you have devised a number
of ways of delivering nicotine to your bodies. Nicotine readily diffuses
through, your skin, Lungs and Mucous membranes (such as the lining of your nose
or your gums)
Nicotine
moves right into the small blood vessels that line the tissues listed above.
From there, nicotine travels through your bloodstream to your brain, and then is
delivered to the rest of your body. The most common and quickest way to get
nicotine and other drugs into your bloodstream is by smoking it. Your lungs are
lined by millions of alveoli, the tiny air sacs where gas exchange occurs. These
alveoli provide an enormous surface area -- 90 times greater than that of your
skin -- and thus provide ample access for nicotine and other compounds. Once in
your bloodstream, nicotine flows almost immediately to your brain. Although
nicotine takes a lot of different actions throughout your body, what it does in
the brain is responsible for both the good feelings you get from smoking, as
well as the irritability you feel if you try to quit. Within 10 to 15 seconds of
inhaling, most smokers are in the throes of nicotine's effects.
Nicotine
doesn't stick around your body for too long. It has a half-life of about 60
minutes, meaning that six hours after a cigarette, only about 0.031 mg of the 1
mg of nicotine you inhaled remains in your body.
Your
body get rid of nicotine by,
-
About 80 percent of nicotine is broken down to cotinine by
enzymes in your liver.
Nicotine is also metabolized in your lungs to cotinine and
nicotine oxide.
Cotinine and other metabolites are excreted in your urine.
Cotinine has a 24-hour half-life, so you can test whether or not someone has
been smoking in the past day or two by screening their urine for cotinine.
The remaining nicotine is filtered from the blood by your
kidneys and excreted in the urine.
Nicotine changes how your brain and body functions. The net
results are somewhat of a paradox: Nicotine can both invigorate and relax you,
depending on how much and how often you smoke.
Nicotine
initially causes a rapid release of adrenaline, the fight-or-flight hormone. You
may be familiar with adrenaline's effects, rapid heartbeat, Increased blood
pressure and rapid shallow breathing.
Adrenaline
also tells your body to dump some of its glucose stores into your blood. This
makes sense if you remind yourself that the fight-or-flight response is meant to
help you either defend yourself from a hungry predator or run away from a
dangerous situation -- running or fighting both require plenty of energy to fuel
your muscles.
Nicotine
itself may also block the release of the hormone insulin. Insulin tells your
cells to take up excess glucose from your blood. This means that nicotine makes
people somewhat hyperglycaemic, having more sugar than usual in their blood.
Some people think that nicotine also curbs their appetite so that they eat less.
This hyperglycaemia could be one explanation why: Your bodies and brain may see
the excess sugar and down-regulate the hormones and other signals that are
perceived as hunger.
Nicotine
may also increase your basal metabolic rate. This means that you burn more
calories than you usually would when you are just sitting around. However,
losing weight by smoking doesn't give you any of the health benefits that you'd
get if you were losing weight by exercising.
It actually does the opposite! Over the long haul, nicotine can increase
the level of your bad cholesterol, LDL that damages your arteries. This makes it
more likely that you could have a heart attack or a stroke.
Nicotine's
effects are short-lived, lasting only 40 minutes to a couple of hours. This
leads people to smoke throughout the day. Add
to this the fact that you can become tolerant to nicotine's effects and need to
use more and more nicotine to reach the same degree of stimulation or
relaxation, and you can see how you can go from smoking one cigarette a day to a
pack a day habit.
Like
any addiction
stopping
is not always easy.
While you're using nicotine, your body adapts the way it works to
compensate for the effects of the nicotine. For example, neurons in your brain
might increase or decrease the number of receptors or the amount of different
neurotransmitters affected by the presence of nicotine. When you no longer have
nicotine in your body, these physiological adaptations for nicotine remain. The
net result is that your body can't function the same way in the absence of the
drug as it did before, at least in the short term. People trying to quit
nicotine experience this as, Irritability, Anxiety, Depression and have a
craving for nicotine
Over
a period of about a month, these symptoms and the physiological changes subside.
But for many smokers, even a day without nicotine is excruciating. Every year,
millions of people try to break the nicotine habit; only 10 percent of them
succeed. Most will throw in the towel after less than a week of trying, because
the way that nicotine rewires the reward system of your brain making nicotine's
pull irresistible.
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