Smoking
Biology: Cambridge International A Level, topic 9.1.2
Smoking and the Respiratory System
Smoking can causes a range of very serious diseases. Cigarette smoke contains harmful chemical such as nicotine, carbon monoxide and carcinogens (cancer-causing chemicals).
Bronchitis
- When smoke is breathed in, it damages the cilia cells of the airways.
- This means the cilia can't waft away the mucus produced by goblet cells, and the mucus builds up.
- This can leads to bronchitis, where the airways are partly blocked with mucus.
Emphysema
- Smoking damages the elastic fibres in the alveoli. This prevents elastic recoil and causes overinnflation of the lungs.
- This can cause emphysema, where gas exchange can't happen efficiently, causing shortness of breath.
- Together bronchitis and emphysema form a condition called chronic obtrusive pulmonary disease (COPD).
- Symptoms include a cough, breathlessness, and wheezing.
Cancers
- The carcinogens in the tar in cigarettes can cause tumours to form in the airways.
- Smoking can cause mouth, throat and lung cancers.
Heart disease and strokes
- Nicotine is very addictive and puts strain on the heart.
- Nicotine acts as a stimulant and causes the heart to beat faster at with greater force. This can increase blood pressure.
- Carbon monoxide reduces the ability of red blood cells to carry oxygen, which can also put strain on the heart. Carbon monoxide binds to haemaglobin with 200x the affinity of oxygen.
- Both of these substances can cause heart disease and strokes.
Test yourself on Smoking
Which disease is not caused by smoking?