Insect Gas Exchange

• What is the function of the strengthened rings in the trachea of insects?

  To prevent the trachea from collapsing
• What are tracheoles in the insect tracheal system?

  Tracheoles are smaller dead-end tubes that extend throughout all body tissues
• How does the tracheal system facilitate oxygen delivery to insect tissues?

  It provides a short diffusion pathway from the tracheoles to any body cell
• What is the process of gas exchange in insects when they are at rest?

  • Cells respire, using up oxygen, lowering its concentration at the ends of tracheoles.
  • Oxygen enters through spiracles, diffusing from the atmosphere into tracheae and tracheoles.
  • Oxygen dissolves in fluid in tracheoles and diffuses down the concentration gradient into cells.
  • CO2 travels down the concentration gradient in the opposite direction.
• What happens to the pressure inside the insect's body when muscles contract during gas exchange?

  The pressure inside increases, forcing CO2 out down a pressure gradient
• Why does mass movement of air occur in insects when they need more air?

  Because the spiracles are closed momentarily, creating a higher pressure of oxygen outside
• How does gas exchange change during vigorous activities in insects?

  • Muscle cells may respire anaerobically, producing lactic acid.
  • Lactic acid lowers water potential in muscles, creating a higher water potential at the tip of tracheoles.
  • Water moves from tracheoles to muscle cells by osmosis, decreasing tracheole volume and drawing air in.
  • Oxygen can then diffuse more rapidly as it doesn't need to dissolve in liquid first.
• Why doesn't the rapid gas exchange occur all the time in insects?

  Because there isn't enough energy to sustain this process continuously
• What are the limits of the insect tracheal system?

  • It relies mostly on diffusion for gas exchange.
  • The diffusion pathway needs to be short.
  • Insects need to be small to maintain effective gas exchange.