Tobacco contains the drug nicotine, a powerful and naturally occuring nerve stimulant. It is extremely toxic and has been classified as the most addictive drug in existence.
60mg of pure nicotine placed on a person's tongue would kill within minutes.
Tobacco has an immediate effect on the body. The pulse increases, breathing becomes faster and more shallow, and blood flow through small blood vessels is reduced due to their constriction.
More than 3,700 substances, some carcinogenic, reach the lungs. Poisonous compounds like carbon monoxide, hydrogen cyanide, and ammonia gas enter the bloodstream.
Carbon monoxide binds to haemoglobin in the blood stream more easily than oxygen, reducing the blood's capacity to carry oxygen to the muscles, heart, and brain.
The oxygen-carrying capacity of a smoker's blood can be cut by up to 15%. This means that the heart has to work much harder to get enough oxygen around the body.
Meanwhile, nicotine begins to feed the cycle of addiction. It stimulates the nervous system and this leads to an increase in heart rate and causes blood vessels to narrow, putting added strain on the heart.
Nicotine also makes blood 'sticky' (more likely to clot), and blocks blood vessels.
Effects of nicotine
Nicotine is a drug found naturally in tobacco. It is as addictive as heroin and cocaine. The body becomes physically and psychologically dependent on it. Once inhaled, it is carried deep into the lungs, absorbed into the bloodstream, and carried to the heart, brain, liver, and spleen.
The initial effect of nicotine is to cause increased alertness, while later a calm, relaxed feeling is induced. Larger amounts lead to dizziness and nausea.
It lowers skin temperature and reduces blood flow to the limbs. It affects many other parts of the body, including the heart, the hormonal system, metabolism, and brain.
Nicotine increases cholesterol levels in the blood, which may cause arteries to clog up with fatty tissue called atheroma. It is metabolised by the liver and lungs and a small amount is excreted by the kidneys. It is broken down into cotinine and nicotine-N'-oxide. In general, a regular smoker will have nicotine or its metabolite (cotinine) present in the body for 3 to 4 days.
Nicotine produces pleasurable feelings that justify the smoker's decision to continue smoking. A tolerance to nicotine builds up over time and more is required to achieve the same effects. This level of nicotine is maintained by further smoking.
The risks to health
Smoking can kill you in over 20 different ways, and there are more than 50 ways in which the habit can make life a misery through illness.
In younger people, smoking can cause fertility problems. Smoking during pregancy severely risks the health of the unborn child.
Smokers are generally of poorer health than non-smokers. Most die from one of the three main ailments associated - diseases of the cardiovascular system, the respiratory tract, and cancer.
03/06/2009