3.3.2 - The Effects of Lung Disease

Tuesday 5th March ‘24

What are the types of lung disease?

How do airway disease affect a person?

• Reduction of the rate of gas echange in alveoli.

• Less oxygen diffuses into bloodstream, body cells receice less oxyfen and rate of aerobic respiration reduced. Lung disease patients often suffer with tiredness or muscle weakness.

• Can affect both ventiilation and gas exchange. Two types of lung diseas which affect ventilation in different ways.

  • Restrictive diseases - makes it difficult to fully breathe in (affects elastic tissue).

    • Severely reduces FVC as breathing in is difficult (FEV₁ is less affected because breathing out is still normal).

    • EG fibrosis.

  • Obstructive diseases - make it difficult to breathe out as airways are blocked.

    • FVC and FEV₁ are both much lower than normal. 

    • EG asthma.

What is tuberculosis?

• Caused by inhalation of bacteria by droplet infection.

• Macrophages in the alveoli build a wall around the bacteria forming a tubercule.

• The bacteria remains alive but dormant. Eventually the infected tissue dies, but damages the alveoli.

• Also causes fibrosis.

• Reduction of tidal volume.

What is pulmonary fibrosis?

• Formation of scar tissue after an infection (e.g. tuberculosis) or from inhaling substances like asbestos.

• Scar tissue is thicker and less elastic than normal lung tissue so lungs are less able to expand and can’t hold as much air as normal.

• Reduction of tidal volume and forced vital capacity.

What is asthma?

• Airways become inflamed because of an allergic reaction.

• Smooth muscle in bronchiole contracts and lots of mucus produced.

• Reduction of FEV1.

What is emphysema?

• Foreign particles (eg from smoking or pollution) trapped in alveoli.

• Causes inflammation, atteacts phagocytes which release an enzyme that can break down the elastin in the walls of alveoli.

• Reduction of alveoli SA.