Gas exchange in insects Flashcards
What is the mechanism of gas exchange in insects
abdomen movement
fluid movement
what are the 3 sections, in order, of an insect
Head
Thorax
Abdomen
components of the insect tracheal system
Spiracles, thracheae, tracheoles
Spiracles?
Openings in the side of insects
Tracheae
Air tubes following on from spiracles
Tracheoles
smaller air tubes following on from tracheae
How many spiracles are on the abdomen
6-8
How many spiracles on thorax
2-4
how does the tracheal system affect SA
Increases SA for efficient gas exchange
By what mechanism do small insects exchange gases throught spiracles
simple diffusion
Through what mechanism do large insects exchange gases throught the spiracles
Ventilation of their tracheal system by rhythmical body movements
Described the process of ventilation
Abdomen expands andd thoracic spiracles open
Air enters thoracic spiracles
Abdomen contracts and forces air out through the open abdominal spiracles
Why do insects have valves over their spiracles
To reduce water loss
When do spiracles open in relation to concentration of gases in the body
When there is a high conc of CO2
Why do spiracles open when CO2 conc is high
So CO2 diffuses out and O2 in quickly bc of the steep conc gradients created
What do tracheoles branch into
Into cell (muscle) or on their surface
What lines the tracheae
chitin
Why are tracheae chitin lined 2x
Strengthen them, makes them impermeable to gas so gas exchange doesnt happen here
At what point in the tracheal system do gases cross into the cells
At the tracheoles which lead into cells
Does O2 diffuse faster through liquid or gas
Gas
What are the conditions of the tracheoles when the insect is at rest
Full of water
What is the condition of the tracheoles when the insect is active
Water is withdrawn into the surrounding cells
Why does water withdraw into cells from tracheoles when insect is active
Production of lactic acid via anaerobic respiration reduces the water potential of the cells
How does the water being withdrawn from he tracheoles affect the rate of diffusion
Increases it
How do insects reduce water loss 2
Spiracles have valves
Exoskeleton made of a thin waxy layer over chitin and protein
Limitation of tracheal system
Diffusion is only efficient over short distances, limits insect size
How do earth worms do gas exchange
Through the skin though they have a circulatory system to deliver oxygen to the tissues-
Benefit of having an impermeable external cuticle layer?
Reduces moisture loss
Why cant insects be larger
Trachea would need to be longer, increases diff distance
Diffusion would be too slow to provide sufficient O2 to repairing cells
Would req more tracheoles, more chitin, more mass: too heavy
why dont insects have respiratory pigments
bc the blood doesnt transport the O2 so there is no need.
Purpose of air sacks in insects tracheal system
Provide a store of air for when spiracles are closed
