Smoking & its impact on health

Tobacco smoke is a mixture of thousands of chemicals, and in this lesson we follow four of the most harmful into the body. First we see what tar and the carcinogens do to the gas exchange system: tar paralyses the cilia and floods the airways with mucus, leading to chronic bronchitis, while enzymes destroy the walls of the alveoli, causing emphysema — together these make up chronic obstructive pulmonary disease, COPD. Carcinogens cause mutations in the DNA of lung cells, so the cells divide uncontrollably to form a tumour, which is lung cancer. Then we turn to the cardiovascular system and the short-term effects of nicotine — a faster heart rate, higher blood pressure, vasoconstriction and sticky platelets — and of carbon monoxide, which binds haemoglobin as carboxyhaemoglobin so the blood carries less oxygen and the heart must work harder. Finally we learn to conduct a questionnaire survey on the incidence of a breathing condition such as asthma or hay fever, and to present the data clearly. This is a health lesson: our aim is to understand, in proper biological detail, exactly how smoking harms the lungs and the heart.