OCR AS Bio Chapter 11: Health and Disease (P189-P191)

Smoking and Health

In the 21st century death is much more likely to be due to heart diseases or diseases of the gaseous exchange system rather than infectious diseases. These common causes of death can be related to lifestyle - specifically smoking.

Tobacco smoke chemicals include; 1. Tar- mixture of substances, some of which cause cancer 2. Nicotine- addictive substance in cigarette smoke; affects brain, other parts of nervous system and cardiovascular system. 3. Carbon Monoxide- gas produced by incomplete oxidation of some substances in tobacco; reduces oxygen-carrying capacity in blood (affects haemoglobin) 4. Particulates- tiny particles, mostly of carbon, cause irritation in lungs and airways (affects cilia hairs)

Each substance is potentially harmful to health. Compounds in cigarette smoke are the direct cause of serious lung diseases and also increase risk of developing CHD or suffering a stroke. These health problems can even be significantly increased by breathing in second-hand smoke i.e. passive smoking.

Lung diseases

These are a major cause of illness/death and include;

Chronic obstructive pulmonary disease (COPD); includes many related diseases, such as, ephysema, that prevent normal airflow through gaseous exchange system. Lung cancer; cells divide uncontrollably forming a tumour. Illnesses; caused by infectious organisms (pathogens) e.g. bronchitis, tuberculosis.

Acute illnesses- happen quickly, last for a short time. e.g. flu (influenza)

Chronic illnesses- e.g. COPD, last over long period of time, sufferer has to learn to live with disease

Chronic obstructive pulmonary disease (COPD)

An illness in which airflow into and out of lungs gradually (and progressively) becomes more and more obstructed. COPD happens to everyone to a certain extent as they get older, but smoking increases its effect dramatically. Around 600 million people suffer from COPD worldwide with 300 million dying each year. Between 80-90% of these cases are caused by smoking cigarettes.

Cigarette smoke contains a wide range of different chemicals, many of which stimulate neutrophils (type of white blood cell). Neutrophils are important for defending the body against infectious disease however in this case they cause illness.

The neutrophils secrete an enzyme called neutrophil elastase. This enzyme is a protease and it breaks down elastin which forms the elastic fibres in the tissues of the airways. Usually, inhibitors prevent the enzyme from being harmful. In a smoker, however, the balance between concentrations of the protease enzymes and inhibitors…