The effect of lifestyle on some non-communicable diseases: The effect of smoking on lung disease and lung cancer.

The idea

Smoking introduces harmful substances into the respiratory system. Tar coats the lining of the airways and destroys cilia, so mucus and pathogens are not swept away; this causes coughing and increases infection risk. Tar also irritates the bronchi and bronchioles, causing them to narrow and produce excess mucus, which restricts airflow and leads to diseases such as chronic bronchitis. Chemicals in cigarette smoke can trigger uncontrolled cell division in the lungs, forming a malignant tumour, so smoking is a major risk factor for lung cancer. Emphysema damages alveoli, reducing the surface area for gas exchange, so less oxygen enters the blood. Because these diseases are non-communicable, they cannot be passed from person to person, but smoking greatly increases the chance of developing them.

What earns the marks

• Tar in cigarette smoke paralyses and destroys the cilia lining the airways, so mucus is not removed and airways become blocked.
• Tar irritates the bronchi and bronchioles, causing them to narrow and produce excess mucus, which reduces airflow and contributes to chronic bronchitis.
• Cigarette smoke contains carcinogens that can cause mutations leading to uncontrolled cell division and the formation of a malignant lung tumour.
• Emphysema damages the walls of the alveoli, reducing the surface area for gas exchange so less oxygen diffuses into the blood.
• Smoking increases the risk of infections such as pneumonia because mucus and pathogens are trapped in the airways.
• Lung cancer and chronic lung diseases are non-communicable, so they are not spread between people but are linked to lifestyle risk factors.

Common mistakes and how to put them right

• Thinking that smoking only affects the lungs.

  Put it right: It also increases the risk of other cancers and cardiovascular disease, but this statement focuses on lung disease and lung cancer.

• Confusing tar with nicotine.

  Put it right: Tar damages cilia and alveoli and contains carcinogens, while nicotine is the addictive substance.

• Stating that lung cancer is infectious.

  Put it right: It is non-communicable and cannot be passed from person to person.

Exam tips

• Link each harmful substance to a specific effect, for example tar to cilia damage and carcinogens to mutations.
• Use the terms cilia, alveoli, surface area and gas exchange accurately when explaining emphysema.
• When asked to compare, refer to risk factors rather than claiming that smoking always causes the disease.