6.6 - Human gas exchange system

• 2 reasons why mammals have an internal gas exchange system ?

  Air isn't dense enough to support delicate structures (alveoli), body would lose too much water via evaporation so organs would dry out
• What is the gross structure of the human gas exchange system ?

  lungs, trachea, bronchi, bronchioles, alveoli
• What are the tracheal walls made of and lined with ?

  Made of muscle and lined with ciliated epithelium and goblet cells
• What is the trachea supported by ?

  Rings of cartilage to prevent it collapsing as the air pressure falls
• What are alveoli lined with ?

  Squamous epithelium
• What 2 things are between alveolus and how do they give an advantage ?

  Collagen and elastic fibre, allow them to stretch and spring back
• Across what surface does gas exchange take place ?

  Alveolar epithelium
• What feature does the bronchi have that moves dirty mucus to throat ?

  Cilia
• What are the bronchiole walls made of and lined with ?

  Muscle and lined with epithelial cells
• How is bronchioles being made of muscles help ?

  Allows them to constrict and control air flow