gas exchange and ventilation in insects

• Terrestrial insects


  • Have microscopic air-filled pipes called tracheae which they use for gas exchange
  • Air moves into the tracheae through pores on the surface called spiracles
• Gas exchange in terrestrial insects

  1. Oxygen travels down the concentration gradient towards the cells

  2. Carbon dioxide from the cells moves down its own concentration gradient towards the spiracles to be released into the atmosphere
• Tracheae

  • Branch off into smaller tracheoles which have thin, permeable walls and go to individual cells
  • Tracheoles also contain fluid, which oxygen dissolves in
• Oxygen and carbon dioxide movement

  1. Oxygen then diffuses from this fluid into body cells

  2. Carbon dioxide diffuses in the opposite direction
• Air movement in terrestrial insects

  1. Insects use rhythmic abdominal movements to change the volume of their bodies and move air in and out of the spiracles

  2. When larger insects are flying, they use their wing movements to pump their thoraxes too
• diagram

  A) abdomen

  B) thorax

  C) trachea

  D) trachea and tracheoles give large surface area

  E) spiracle

  F) tracheole lined with single layer of cells

  G) oxygen diffuses into respiring cells

  H) carbon dioxide diffuses into tracheoles