Insects

• Why can't insects use their bodies as an exchange surface?

  Waterproof exoskeleton

  Small SA:V - conserve water
• Three main features of an insects gas transport system

  Spiracles

  Tracheae

  Tracheoles
• Spiracles

  Holes on the body's surface which may be opened or closed by a valve for gas or water exchange
• Tracheae

  Large tubes extending through all body tissues
• Tracheoles

  Smaller branches dividing off tracheae
• Explain the process of gas exchange in insects

  Gases move in and out of the tracheae through the spiracles

  A steep diffusion gradient allows oxygen to diffuse into the body tissue while waste CO2 diffuses out

  Contraction of muscles in the tracheae allows mass movement of air in and out