Gas exchange

• What is the trachea ?


  a tube where air passes through into the lungs
• What are the rings of cartilage for?

  prevents the trachea from collapsing when you inhale
• What is the bronchi ?

  trachea splits into two smaller tubes , each passing into the lungs
• What is bronchioles ?

  bronchi subdivides into many smaller tubes
• There are tiny sac in the bronchioles called the alveoli
• What is an alveoli ?

  Where gases diffuse in and out of the bloodstream
• How are alveolis adapted to gas exchange ?

  • have a huge surface area
  • very thin walls so diffusion path is short
  • good blood supply
• How does alveoli work ?

  • oxygen in the air diffuses into the bloodstream
  • carbon dioxide diffuses out of the bloodstream into the air
• What happens when oxygen diffuses into the blood ?


  its rapidly removed to keep the concentration gradient steep
• What are key points about breathing ?

  • breathing increases the rate of diffusion
  • brings in fresh oxygen into alveoli and takes away the carbon dioxide
  • increase the concentration gradient and increasing the rate of diffusion