Gas exchange in insects

Exoskeleton of chitin Lipid layer - prevents water by evaporation

Diffusion and is only possible due to a short diffusion pathway

Maintain the perfect balance of oxygen uptake and minimising water loss

Round valve-like openings along abdomen ( Can close and open to stop water loss evaporating) Oxygen can diffuse in down its concentration gradient Carbon dioxide can diffuse out along up the concentration gradient

Network of internal air filled tracheae Extend throughout into tissues Delivered oxygen to respiring cells Branches off into tracheoles

Simple diffusion Mass transport Insect in flight

Oxygen diffuses in down concentration gradient Carbon dioxide diffuse out along concentration gradient Large SA:V ratio

Contracts and relaxed abdomen muscles Compresses tracheae Raises pressure in the body and forces air out the body down the pressure gradient Increases removal of carbon dioxide Energy demand and respiration levels are highest

Respire anaerobically This produced lactic acid Lactic acid lowers water potential of cells Water at the end of tracheoles moves into cells by osmosis More air at the end of tracheoles and less pressure Oxygen and carbon dioxide diffuse in and out faster, This is because air travels faster in gas then liquid and the volume decreases in tracheoles

Tracheoles have thin walls - This shortens diffusion pathway Tracheoles are highly branched - Increases SA : V ratio