Lung Disease in Humans

• What is ventilation rate?

  The volume of air entering the lungs in a minute
• What is tidal volume?

  The volume of air in each breath
• What is residual volume?

  The volume of air that remains in the lungs to make sure they never fully deflate
• What is breathing rate?

  The number of breaths per minute
• A device called a spirometer can measure breathing rate, tidal volume and ventilation rate
• The results from a spirometer trace can show the volume changes in the lungs
• How can the health and function of a persons lungs be measure?

  By looking at their forced expiratory volume and forced vital capacity
• What is forced expiratory volume?

  The maximum volume of air that can be exhaled in one second
• What is forced vital capacity?

  The maximum volume of air that can possibly be forcefully exhaled from the lungs
• How is ventilation rate calculated?

  Ventilation rate = tidal volume x breathing rate
• Lung disease can affect both ventilation and gas exchange
• All lung diseases reduce the rate of gas exchange in the alveoli
• Why do lung disease patients often suffer from tiredness and weak muscles?

  The rate of gas exchange in the alveoli is reduced, meaning that less oxygen diffuses into the bloodstream, less oxygen is received by body cells and thus the rate of aerobic respiration is decreased
• What are the two types of lung diseases?

  Obstructive and restrictive.
• Restrictive diseases make it difficult to fully breathe in as they typically affect elastic tissue
• Restricted diseases severely reduce forced vital capacity as inhaling is difficult, but forced expiratory volume is less affected as exhaling is normal
• Obstructive diseases make it difficult to breathe out as the airways are blocked
• Obstructive diseases cause the forced vital capacity and forced expiratory volume to be much lower than normal
• What is the cause of tuberculosis?

  Inhaled bacteria by droplet infection
• How is tuberculosis formed?

  The macrophages build a wall around the bacteria in the alveoli, forming small hard lumps, eventually the infected tissue dies, which damages the alveoli
• What are the effects of tuberculosis?

  Reduced gas exchange as the damaged alveoli have a smaller surface area, thick scar tissue (causing a larger diffusion pathway) and the elasticity in the lungs is reduced, so they cannot hold as much air as normal
• Tidal volume is decreased and ventilation rate is increased when an individual has tuberculosis
• What are the symptoms of tuberculosis?

  Persistent cough, potentially coughing up mucus and blood, shortness of breath and fatigue
• What is the cause of pulmonary fibrosis?

  Formation of scar tissue in the lungs after an infection or as a result of breathing in substances like asbestos
• Pulmonary fibrosis reduces gas exchange as:

  Scar tissue is thick, so diffusion rate is reduced as there is a larger diffusion pathway, and elasticity is reduced so the lungs cannot expand and hold as much air as normal
• Tidal volume decreases and ventilation rate increases when an individual has pulmonary fibrosis