breathing and lung disease

• Inhalation:

  • diaphragm contracts
  • external intercostal muscles contract pulling ribcage moves up and out
  • increases the volume of the thoracic cavity which reduces the air pressure because there is more space
  • air moves into the trachea down the pressure gradient
  • its an active process (requires energy)
• exhalation:

  • diaphragm relaxes
  • external intercostal muscles relax, ribcage moves in and down
  • decrease the volume of the thoracic cavity which increases the air pressure because there's less space
  • air moves out the trachea down the pressure gradient
  • normal expiration is a passive process (no energy)
• the human chest cavity is always at a lower pressure than the outside environment
• ventilation rate - volume of air entering the lungs in a minute
• tidal volume - volume of air in each breath
• breathing rate is a number of breaths per minute
• forced expiratory volume - maximum volume of air that can be breathed out in 1 second
• forced vital capacity - maximum volume of air thats possible to breath out forcefully
• restrictive diseases:

  • make it difficult to breathe in
  • severely reduces FVC as breathing is difficult but FEV is less effected
• obstructive diseases:

  • make it difficult to breathe out as airways are blocked
  • FVC and FEV are both much lower than normal
• lung disease effects both gas exchange and ventilation
• the diaphragm moves to lower the pressure in the chest cavity and pull air into the lungs