Alveoli, Capillaries and Gas Exchange

• The alveoli are well adapted to exchange gases because:

  • they are only one cell thick
  • they have a large surface area
  • they are surrounded by a capillary network (i.e. the bloodstream)
• Gas exchange happens in the alveoli.
• What does this diagram show?

  Gas exchange happening in an alveolus.

  
• Oxygen - the unreactive gas that makes up most of the air around us.
• Carbon dioxide - this gas is a waste product of respiration.
• Alveoli - the air sacs where oxygen enters and carbon dioxide leaves the blood.
• Blood capillary - the tiny blood vessel that surrounds the alveoli.
• Deoxygenated blood - blood that contains less oxygen and is deep red (represented as blue in diagrams)
• Oxygenated blood - blood that contains oxygen gas (represented as red in diagrams)
• Nitrogen - that gas that is used in the body to release energy from food.