Gas exchange in insects Flashcards
Where does air enter insects?
Through pore in their side called spiracles into their trachea
How does oxygen move in the trachea?
Down their concentration gradient toward body cells into tracheoles which branch of the trachea
How does oxygen diffuse into body cells?
Down the tracheoles and diffuses into the body cells (respiring) because they have thin permeable walls
How does carbon dioxide move out of the insect?
Diffuses down its concentration gradient out the cell into tracheole, then out through spiracles
What do insects do to move air in an out of spiracles?
Rhythmic abdominal pumping to increase pressure
Adaptation of insects to increase gas exchange?
The trachea and tracheoles provide a large surface area for gas exchange
Thin walls = shirt diffusion pathway
How do insects reduce water loss?
Impermeable cuticle
Spiracles have hair to trap water to reduce water potential gradient
Closing valves of spiracles using muscles so water doesn’t leave
Why is water loss by evaporation a problem for TERRESTRIAL insets?
Live on land so not near water
Relatively small so high surface area: volume ratio + short diffusion distances = high rates of water loss by evaporation
Impermeable cuticle on insects
Impermeable to gases so gas exchange can only occur through open spiracles
INSECT vs XEROPHYTE gas exchange
Both occur through pores (stomata in leaves/spiracles in insects)
These pores can be closed to reduce water loss
Gas diffuses direct to cells from the atmosphere e.g. oxygen via tracheae/tracheoles in insects; carbon dioxide via air spaces in leaf spongy mesophyll
