Carbon monoxide is the same odorless,
colorless gas that comes out the tailpipe of your car or a faulty gas
heater. In high enough concentrations it is deadly; in lower doses it
causes shortness of breath and increased heart rate.
Normally red blood cells carry oxygen
through out the body by binding it to a molecule called hemoglobin.
Carbon monoxide attaches itself to hemoglobin instead of oxygen and
deactivates these red blood cells for extended periods of time.
Eventually the carbon monoxide falls off or the red blood cells are
replaced; in the mean time, however, this carbon monoxide can be
replaced by continued smoking. This is one of the key reasons athletes
almost never smoke as over 10% of the body's hemoglobin can be
inactivated at any one time.
The body is able to eliminate most of
the carbon monoxide fairly quickly. Most people who quit feel more
energetic and less short of breath within a few days of quitting.
Although only one of many dangerous
substances in cigarettes, nicotine is the drug responsible for making
cigarettes so addictive. Studies have shown nicotine to be as
addictive as heroin and cocaine.
Within 7 seconds of inhaling on a
cigarette, the nicotine has reached your brain. The drug acts upon
receptor cells providing the "hit" that your body expects.
This triggers various responses in your body; your heartbeat and
breathing rate go up and blood vessels constrict.
By the time you have extinguished the
cigarette, the nicotine level in your blood will have peaked; within a
half-hour your body will have cleaned it out of the blood stream. This
spiking is part of what makes cigarettes so addictive. The method of
delivery --direct to the lungs and then to the brain -- and the
intensity of its effects, help to make nicotine extremely addictive.
In the morning most smokers inhale
deeply on their first cigarettes as the nicotine content in the blood
has dropped overnight and they are quite practically in withdrawal. In
reality smokers spend much of their time in withdrawal; stress,
anxiety and boredom are all heightened by daily withdrawal in
between cigarettes. In between cigarettes every smoker goes
through a small scale version of what the quitter does. Over the day
the smoker smokes enough cigarettes to maintain a sufficient nicotine
blood level to prevent these withdrawal symptoms. Usually the minimum
number to achieve this (regardless of nicotine content of the
cigarette) is 10-12 cigarettes spaced over the day. Generally this
explains why people who smoke less than half a pack a day are
Nicotine also acts as a
vasoconstrictor, meaning it decreases the diameter of your blood
vessels making it more difficult for blood to flow through the body.
This can lead to higher blood pressure and forces the heart to work
harder. It may be one of the reasons for increased heart disease in
long time smokers. More obvious indications are cold or clammy hands,
as the extremities do not receive as much blood.
Just how and why nicotine affects the
brain the way it does is poorly understood. While we know that it can
act as both a stimulant (giving smokers a lift) or a depressant
(relaxing smokers when they feel tense, or stressed.) Much of this
seems dependent upon dosage and current levels of nicotine in the
blood. For the moment we will just accept that it acts the way it does
without stressing about it.