insects

• gases enter and exit insects by spiracles in their skin
• spiracles are closed when not breathing so water loss is reduced
• the walls of tracheal system are thin so gases diffuse easily across them
• Insects use muscles to increase rate of breathing processes
• spiracles (insects)= holes on the surface of the body which can be opened and closed by a valve for gas or water exchange
• tracheal tubes (insects)= large tubes extending through all body tissues , supported by rings of chitin
• tracheoles (insects)= smaller branches from the tracheal tubes
• tracheoles have fluid at the ends to make gas exchange more efficient - Fluid in the end of the tracheoles moves out into tissues during exercise so larger surface area
• explain gas exchange in insects:

  • gases move in/out of the tracheal tubes through spicicles
  • a diffusion gradient allows O2 to diffuse into body tissue while co2 diffuses out
  • the contraction of the muscles in the tracheal tubes allows the movement of air in and out