Tobacco today has been proven as our most popular and most problematic drug.
In 1995 there were over 97,000 adult, smoke-related deaths. It is widely known
that smoking increases your risk of heart disease, can cause cancer and should
be avoided during pregnancy. How can we prove these claims, is there any medical
evidence for them?
There are three main components of tobacco: nicotine, carbon monoxide and
Nicotine is a very powerful, highly addictive stimulant drug. This is the
drug that most people are addicted to in the cigarette. When a smoker inhales,
nicotine is absorbed into their bloodstream and the effects are felt on the
brain seven to eight seconds later. Nicotine also effects the rest of the body
in different ways. In small amounts nicotine stimulates nerve impulses in the
central and autonomic nervous system (part of the nervous system which regulates
heart, adrenal gland, bladder etc.) while in large amounts nicotine inhibits
these nerve impulses.
The immediate effects of nicotine are:
Increase in heart rate, blood pressure and hormone production
Constriction of small blood vessels under the skin
Changes in blood composition and metabolism
Carbon monoxide is a poisonous gas found in relatively high concentrations in
cigarette smoke. It combines with the oxygen carrying substance in blood,
haemoglobin. It will replace the oxygen in the blood so that up to 15% of the
smokers blood may be carbon monoxide instead of oxygen. Oxygen is essential for
body tissues and cells to function properly. If the supply of oxygen is reduced
for long periods it can lead to problems with growth, repair and absorption of
Smoking or passive smoking is therefore particularly harmful during pregnancy
as the carbon monoxide reduces the amount of oxygen carried to the uterus and
fetus. Carbon monoxide can also encourage fatty deposits to form on the walls of
arteries. This can lead to the arteries becoming blocked and other circulation
When a smoker inhales, the cigarette smoke condenses and about 70% of the tar
contained in the smoke is deposited in the lungs. High levels of tar on the
lungs, over a period of time, can lead to cancer. Irritants in tar can also
damage the lungs by causing narrowing of the bronchioles, coughing, an increase
in bronchiole mucus and damage to the small hairs which protect the lungs from
dirt and infection.
The amount of nicotine, carbon monoxide, tar and other substances that are
absorbed into the body, from a cigarette, varies greatly, and depends on how
much the smoker inhales.
The facts and figures were obtained from - Smoking: The Facts. Published by
Health Education Authority.