Tracheal system (insects)

• Properties of gas exchange systems:

  • large SA
  • Thin
  • Partially permeable
  • Movement of external materials
  • movement of internal materials
• Insects have holes (spiracles) in their exoskeleton/ skin
• Insects have adapted in order to conserve water by having a small SA:V ratio and having waterproof coverings
• Tracheal tubes run from the body surface directly into tissues/ cells
• Insects have a low metabolic rate
• Spiracles are holes in insects exoskeletons that can open and close. There are a pair of lip like openings called spiracles on every segment of the body
• Tracheal tubes connect spiracle branches to a series of tracheoles
• Tracheoles divide until they penetrate body cells
• Spiracles can close which prevents water loss and open when respiration is needed
• How are gases exchanged?

  • Diffusion gradient
  • Mass transport
  • Tracheole ends are filled with water
• Tracheoles are made of chitin which means they won't collapse under pressure
• Tracheole fluid enables gas exchange
• when there isn't enough oxygen, anaerobic respiration takes place which produces lactate
• The presence of lactate in the muscle cells lowers the water potential and causes the tracheole fluid to move into the cells. This creates more space in the tracheoles and allows gas exchange to happen at a faster rate