gas exchange in lungs

• the heart..

  pumps blood into the lungs where the blood collects oxygen
• the blood is then...

  returned to the heart and is pumped around the whole body delivering oxygen to body cells
• The long tube passing air into the lungs

  trachea
• the trachea is adapted how?

  rings of cartilage preventing the trachea from collapsing during inhalation
• the trachea divides into two tubes called..

  bronchi
• the bronchi subdivides further into...

  bronchiholes
• the bronchiholes contain..

  alveoli
• what are alveoli?

  air sacs that are sites of gas exchange
• how are alveoli adapted to increase rate of gas exchange?

  • millions of them for increased surface area
  • very thin walls for short diffusion path
  • good blood supply
• breathing also does what?

  increase rate of diffusion
• breathing

  breathing brings fresh oxygen into alveoli and takes away carbon dioxide