3.2.8

Lung Disease

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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.

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Diseases

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

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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.
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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.
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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.

Jump to other topics

1Biological Molecules

2Cells

3Substance Exchange

4Genetic Information & Variation

5Energy Transfers (A2 only)

6Responding to Change (A2 only)

7Genetics & Ecosystems (A2 only)

8The Control of Gene Expression (A2 only)

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