Insects

• Insects

  • Insects on land have obtain oxygen from air without dying of dehydration; two conflicting needs:
  • Exchange of respiratory gases
  • Reduce water loss
  • Although tracheal system is highly effective for gaseous exchange, most insects it relies on diffusion of O_2 through body
  • Have no transport system, like blood, to move oxygen or carbon dioxide around body
  • For larger, more active insects:
  • Expiration
  • Flight muscles contract and flatten body
  • Tracheal system volume decreases
  • Air forced out
  • Inspiration
  • Achieved passively as elastic nature returns them to original shape
• Gas Exchange

  • Insects can close spiracles with valves in cuticle
  • Reduce water loss
  • Some even have hairs
  • Prevents excess oxygen

  Inactivity and activity

  • When insect is less active, tracheoles ends contain fluid
  • As activity increases, fluid is removed
  • Muscle cells produce lactic acid
  • Lowers cell’s water potential
  • Gas exchange is near cells, quicker
  • When cells actively respire
  • O_2 is used up
  • So its concentration at tracheoles end falls
  • Creating diffusion gradient for O_2 towards cells
  • CO_2 produced by respiring cells
  • Creates diffusion gradient with atmosphere, it move out
• Insect Adaptations

  Fill in Table

  A) O_2

  B) CO_2

  C) valves

  D) water loss

  E) Chitin

  F) trachea

  G) Gaseous

  H) tracheal

  I) Narrower

  J) Thin

  K) Short