Smoking and DiseaseAN IN-DEPTH LOOK AT THE CORRELATION BETWEEN SMOKING AND DISEASE

Why is it such a big deal?

▪WHO considers smoking to be a disease.▪ It became popular among European men during First World War.▪ Eventually in the 1940s lots of women also started smoking.▪ In Pakistan, 40% of men and 12% of women smoke.▪ Each day, more than 1200 young people take up smoking.

How do cigarettes adversely affect our health?

▪ 3 main components of cigarette smoke that threaten our health:▪ Tar: Settles on the lining of the airways in the lungs. Leads to

obstructive lung diseases and lung cancer.▪ Carbon monoxide: Substitutes O2, diffuses into red blood cells

to form carboxyhaemoglobin which is stable. Less O2 in blood. Less O2 supply to the heart muscle. Also damages lining of arteries.▪ Nicotine: Stimulates nervous system to reduce diameter of

arterioles and to release adrenaline. Results in reduction of O2 supply in far ends of body and increase in heart rate and blood pressure. Also makes platelets more sticky, thus increasing risk of blood clotting.

Why are our lungs susceptible to diseases?

▪ We are constantly exposed to moving air streams which may carry potentially harmful gases and particles.▪ Despite our sophisticated filtering system, very small

particles can pass through and settle in the alveoli.▪ These particles make our lungs vulnerable to air-borne

infections such as influenza and pneumonia and, in some people, can cause an allergic reaction.▪ Chronic (long-term) diseases such as asthma, chronic

bronchitis, and emphysema prevail as a result of atmospheric pollution.

How do allergies happen?

▪ Some particles can be allergic to some people. They trigger a defense mechanism in our airways. If this is bad enough, it may cause asthmatic attack in which the smooth muscles in the airways contract.▪ The body’s defense mechanisms may react with the

production of more mucus and the collection of white blood cells in the airways. This can block the airways and cause severe coughing, which can damage the alveoli.▪ Continuous damage can lead to the alveolar surface

being replayed by scar tissue. This reduces surface area for diffusion.

How do allergies happen?

Are these diseases significant enough?

▪Lung diseases are the third most common cause of illness and death in the UK.▪One in seven children in the UK has asthma.▪To further aggravate this problem, there are no legal controls in the UK regarding tobacco smoke.

You mentioned chronic bronchitis. What is it?

▪ Tar in cigarette smoke stimulates secretion of mucus.▪ It destroys many cilia and weakens sweeping action of those

that remain.▪ Mucus accumulates in the bronchioles.▪ Dirt, bacteria and viruses block the bronchioles as well.▪ Eventually the damaged epithalia are replaced by scar tissue

and the smooth muscles surrounding the bronchioles and bronchi become thicker, making it more difficult for air to move in/out the lungs.▪ Infections can easily build up in the mucus. When this happens

the linings become inflamed, further narrowing the airways. = CHRONIC BRONCHITIS

What about emphysema?

▪ Inflammation of infected lungs causes phagocytes to line the airways.▪ Phagocytes release elastase which destroys elastin in the walls of alveoli so as

to make way for them to reach the surface and remove bacteria. Elastin is responsible for the recoil of the alveoli when we breathe out.

▪ As a result, the bronchioles become “flabby” and some of the alveoli burst and form fewer larger ones. This reduces surface area for gaseous exchange.

Chronic obstructive pulmonary disease

▪ Chronic bronchitis and emphysema often occur together and are collectively called chronic obstructive pulmonary disease which is a progressively disabling disease.

Lung cancer?

▪ Tar in tobacco smoke contains carcinogens▪ These react with DNA in epithelial cells to produce

mutations; malignant tumor is developed.▪ As the first cancer develops, it spreads through the

bronchial epithelium and enters the lymphatic tissues in the lung.▪ Cells may break away and spread to other organs so

that secondary tumors become established.