Gas Exchange in Insects Flashcards
What is the exoskeleton of an insect made up of?
Chitin
What does chitin do?
It is a hard, fibrous material that protects the insect.
How is water loss prevented in chitin?
The chitin has a lipid layer to prevent water loss.
What do insects have instead of lungs?
The tracheal system.
What does terrestrial mean?
Living on land.
What 3 adaptations do insects have to reduce water loss?
Small surface area to volume ratio
Spiracles
Exoskeleton
How does the exoskeleton reduce water loss?
The exoskeleton is waterproof as it is made up of chitin which has a lipid layer that prevents the water loss.
What are spiracles?
Spiracles are tiny holes on the abdomen that can open and close to allow diffusion.
How do spiracles reduce water loss?
They’re small and can open and close to reduce water loss.
How does a small surface area to volume ratio reduce to water loss?
The small surface on the side of the spiracle has a tiny little hole where water can evaporate from.
What 3 things make up the tracheal system?
Trachea
Tracheoles
Spiracles
Describe spiracles in detail.
Round valve-like openings running along the length of the abdomen. They lead into the tracheal tube system. Oxygen diffuses into the spiracles, carbon dioxide diffuses out. The trachea attach to the spiracles.
What are trachea?
Large tubes full of air that allow diffusion.
What is an adaptation of the trachea?
They have rings within them to strengthen the tubes and to keep them open.
What are the tracheoles?
Smaller branches from tracheae. They are permeable to allow gas exchange with cells.
What do the tracheoles do?
They reach every single tissue within the insect to deliver oxygen to the respiring cells.
How do gases exchange by diffusion in insects?
When cells respire, they use up the oxygen and produce carbon dioxide. This creates a concentration gradient from the tracheoles to the atmosphere.
How do gases exchange by mass transport in insects?
The insect contracts and relaxes their abdominal muscles to move gases on mass in and out of the insects tracheal system.
What happens when the insects are flying?
The muscle cells respire anaerobically to produce lactic acid. This lowers the water potential of the cells and thus water moves from the tracheoles into the cells by osmosis. This decreases the volume in the tracheoles and as a result more air from the atmosphere is drawn in.
What provides a large surface area in insects?
Large number of tracheoles and spiracles.
What provides a short diffusion pathway in insects?
The walls of the tracheoles are thin.
Short distance between spiracles and tracheoles.
What provides a maintained concentration gradient in insects?
Use of oxygen and production of carbon dioxide.
How is an insect’s tracheal system adapted for gas exchange? (5)
1)Tracheoles have thin walls so short diffusion distance to cells.
2)High numbers of highly branched tracheoles provides a large surface area.
3)Tracheae provide tubes full of air for fast diffusion.
4)Contraction of abdominal muscles changes pressure in body causing air to move in/out which maintains a conc gradient.
5)Fluid in the end of tracheoles are drawn into tissues by osmosis during exercise. Thus diffusion is faster through air rather than fluid to gas exchange surface.
Explain structural and functional compromises in terrestrial insects that allow efficient gas exchange while limiting water loss.
Spiracles can open to allow gas exchange and close to reduce water loss by evaporation.
Hairs around spiracles trap moist air reducing water potential gradient so less water loss by evaporation.
Thick waxy cuticle increases diffusion distance so less water loss by evaporation.
