Human Gas Exchange

• Hierarchy of Human Gas Exhange

  • Lungs
  • Trachea
  • Brochi
  • Bronchioles
  • Alveoli
• Ventiliation is using the diaphragm and an antagonistic interaction between internal and external intercostal muscles
• External Intercostal Muscles contract leading to inspiration
• Internal Intercostal Muscles contract leading to inhilation
• Inspiration Process:

  • External contract, pulls ribs up and out, Internal relax
  • Diaphragm contracts and flattens
  • Air pressure initially drops, air moves down the atmospheric pressure gradient as it is higher on the outside
  • Lung volume increases
• Expiration Proces:

  • Internal contract, pulls ribs down and in, External relax
  • Diaphragm relaxes, moves up and domes
  • Air pressure initially is greater, air moves out of the lungs due to atmospheric pressure gradient being higher in lungs
  • Lung volume decreases
• Pulmonary Ventilation (dm3 min-1) = Tidal Volume (dm3) x Ventilation Rate (min-1)
• Alveolar Epithelium increase surface area, cells are very thin to minimise diffusion distance, networks of capillaries to remove gas maintaining a concentration gradient