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Lung Disease

Applied Science: BTEC Level 3 National Extended Diploma, topic 4.6.5

Overview of Lung Disease

Lung disease affects the ability of the lungs to exchange gases over their surface. This can be direct tissue damage or a reduced ability to ventilate.

Diseases

Diseases

  • Lung diseases can cause issues with gas exchange and ventilation. Diseases include:
  • Asthma.
  • Pulmonary fibrosis.
  • Tuberculosis.
  • Emphysema.
Causes

Causes

  • Gas exchange problems are caused when the exchange system is damaged.
  • The causes of these problems can include:
  • Decreased surface area.
  • Increased diffusion distance.
  • Decreased concentration gradient.
Symptoms

Symptoms

  • Symptoms of gas exchange or ventilation issues include:
  • Coughing mucus or blood.
  • Faster, shallower breathing.
  • Blood oxygen saturation readings below 90%.
  • Fatigue.

Effects of Lung Disease

Different lung diseases have different effects on gas exchange and/or ventilation in the respiratory system. These effects include:

Emphysema

Emphysema

  • Emphysema is caused by smoking or air pollution.
  • Dirt and bacteria become trapped in the alveoli which damages the alveoli walls.
  • The alveoli provide a large surface area for gas exchange.
  • Damage to the walls decreases the surface area and rate of gas exchange declines.
Asthma

Asthma

  • Asthma increases the production of mucus by the epithelial cells.
  • The increased mucus increases the length of the diffusion distance.
  • The greater diffusion distance decreases the rate of gas exchange.
  • An asthma attack also causes the smooth muscle in the bronchioles to contract. This makes it difficult to breathe.
Tuberculosis

Tuberculosis

  • Tuberculosis bacteria can infect the lungs, damaging the lung tissue.
  • The cells of the immune system can also damage the lungs.
  • The damaged lungs lead to a decreased tidal volume.

Test yourself on Lung Disease

  • What are the problems caused when the lungs are damaged?

  • Which of these is NOT a disease caused by issues with gas exchange and ventilation?

  • Which of the following statements about emphysema are true?

  • Which of these is NOT an effect of asthma on lung function?

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