Gas Exchange In Insects Flashcards
What is the internal network of tubes called and why have insects developed it?
Tracheae, evolved for gas exchange to reduce water loss.
What is the structure of the tracheae?
Supported by strengthened rings of cartilage to prevent them collapsing. Divided into smaller dead-end tubes called tracheoles.
What is the role of the tracheoles?
Extend throughout body tissue of insect to ensure atmospheric air is brought directly to the respiring tissues to create a small diffusion pathway.
How is oxygen moved in and out of the tracheal system along a diffusion gradient?
Oxygen is used up in cell respiration, so concentration towards end of tracheoles falls, creating a diffusion gradient for oxygen to diffuse into cells from tracheoles.
How is carbon dioxide moved in and out of the tracheal system along a diffusion gradient?
Produced by cells during respiration, creating a diffusion gradient where it diffuses out of cells, into tracheoles and out.
How is Mass Movement important in moving gases in and out of the tracheal system?
Contraction of muscles in insects can squeeze the trachea, enabling mass movements of air in and out, to further speed up exchange of respiratory gases.
How is respiratory gas exchange made more effective by filling the ends of tracheoles with water?
Anaerobic respiration produces lactate which is soluble and lowers water potential of muscle cells. Water therefore moves into the cells by osmosis, water in tracheoles decreases in volume and so draws more air in.
What is the final diffusion pathway feature in the tracheal system?
In a gas rather than liquid phase, therefore diffusion is more rapid, increasing rate air moves into tracheoles but leads to greater water evaporation.
What are spiracles?
Tin y pores in the tracheae that gases enter and leave through.
How are Spiracles operated?
They are opened and closed by a valve.
Why are spiracles kept closed?
Insects keep spiracles closed to prevent water vapour evaporating through, and therefore preventing water loss. Spiracles are only opened to allow exchange.
What are the limitations of the insects tracheal system?
Relies mostly on diffusion to exchange gases between environment and cells. Diffusion pathway needs to be short, which is why insects are of a small size.
