Insects Flashcards
(13 cards)
Why do insects need gas exchange?
Insects have high oxygen demands but their tough chitinous external skeleton (exoskeleton) prevents direct gas exchange
- To deliver oxygen to cells - This allows aerobic respiration to occur to release energy for cellular processes
- To remove carbon dioxide from cells - The build up of carbon dioxide produced as a waste product of respiration reduces pH, which can denature enzymes
What two conflicting needs have insects adapted to?
Maximising gas exchange efficiency
Minimising water loss
What is a trachea?
These are air-filled tubes branching throughout the body
What are tracheoles?
These are fine branches of tracheae that deliver gases to cells
What are spiracles?
These are external openings of the tracheal system on the exoskeleton along the abdomen and thorax
How are trachea adapted to their function?
Reinforced with spirals of chitin
- This prevents collapsing
Multiple tracheae
- This increases surface area
How are tracheoles adapted to their function?
5x
Penetrate directly into tissues
- This reduces the gas diffusion distance
Thin walls
- These reduce the gas diffusion distance
Highly branched
- This maximises the surface area.
Not reinforced with chitin
- This allows gas exchange to occur
Fluid at the ends of the tracheoles (tracheal fluid)
- This allows oxygen to dissolve to aid diffusion and reduces water loss
How are spiracles adapted to their function?
Open and close
- This allows them to control gas exchange with the atmosphere and minimise water loss
How does gas exchange occurs in insects?
6 steps
- Air enters the tracheal system through open spiracles
- Air moves into larger tracheae and diffuses into smaller tracheoles
- Tracheoles branch throughout the body, transporting air directly to cells
- Oxygen dissolves in water in tracheal fluid and diffuses down its concentration gradient from tracheoles into body cells
- Carbon dioxide diffuses down its concentration gradient out of body cells into the tracheoles
- Air is then carried back to the spiracles via the tracheae and released from the body
How is the concentration gradient between tissue and air in tracheal system maintained?
Cells using up oxygen for respiration
- This keeps oxygen concentration low in cells
Cells producing carbon dioxide in respiration
- This keeps carbon dioxide concentration high in cells
Continuous ventilation
- Fresh air is supplied to the tracheal system via spiracles.
How does gas exchange occur with wings?
They have an air reserve:
- Air can be stored when organsims needs to close its spiracles (hot day)
- When the insect jumps/moves it helps to change the volume of the body cavity
- This causes change in pressure
- Helps to draw air out
What happens when an organism switches to anaerobic respiration?
- Produces lactic acid, reduces the pH in the cells of the surrounding the muscle tissue
- Fluid moves from the tracheoles into surrounding mucsle tissues via osmosis due to lactic acid build up
- More oxygen can diffuse further into the muscle fibres and more oxygen is available for aerobic respiration
Dissection of insects and fish
- To see the spiracles, the exoskeleton needs to be carefully removed
- To see the gill filaments the operculum needs to be carefully removed
