Gas Exchange- Insects

Gas Exchange- Insects

1. Active

   • Movements of abdomen ventilate the tracheae
   • Ends of tracheoles fluid-filled and close to muscle fibres
   • Interface where gas exchange takes place
   • Oxygen dissoles in fluid and diffues directly in muscle cells
   • No respiratory pigment or blood circulation need
   • CO2 diffuses reverse

2. Resting

   • Diffusion through spiracles, tracheae and tracheoles
   • Same method for O2 and CO2

3. Problems

   • Live in arid so water evaporates from body risking dehydration
   • Gas exchange need thin permeable surface conflicts with water conservation
     • Insects therefore have waterproof layer (e.g. exoskeleton with thin waxy layer over thick layer of chitin and protein

4. Structure

   • Paired holes:spiracles
     • Branches chitin lined tubes:tracheae
       • Smalles tubes: tracheoles
     • Can open and close: reduces water loss
     • Hairs on spiracles: reduces water loss and prevents solid particles entering