Gas Exchange in Fish and Insects Flashcards
Do small organisms have a small or large SA to volume ratio?
large
How does an increased SA (needed for gas exchange) impact water loss?
Water will be lost/evaporate more easily due to the high SA
What are the internal tubes that insects have for gas exchange?
tracheae
What are tracheoles?
smaller dead-ended tubes that come off of the tracheae and extend to all the tissues in the insect
What 3 ways can respiratory gases move in and out of the tracheal system of insects?
- along a diffusion gradient
- mass transport
- tracheoles ends are filled with water
How does water in the tracheoles’ ends allow for respiratory gases to be exchanged?
- major activity –> anaerobic respiration –> lactate is produced
- lactate lowers water potential of muscle cells
- water moves into cells from tracheoles by osmosis
- volume of water in tracheoles decreases, which draws in more air
What are gills made up of?
gill fillaments, which are stacked up, and made up of gill lamellae (which are perpendicular)
What is the essential feature of the counter-current exchange system?
water flows over surface in opposite direction to the flow of blood
How does the counter-current exchange principle allow for efficient gas exchange?
maintains a concentration gradient, which allows for oxygen to diffuse from water into the blood
Give 3 ways insects limit water loss
- small SA to volume ratio
- waterproof coverings (chitin)
- spiracles (can be closed if insect is at rest)
Why might some insects have gills?
- higher metabolic rate
- uses more
oxygen
Why would reduction in movement reduce water loss in insects?
- less respiration so less gas exchange
- so spiracles open less so less water loss
How is the gaseous exchange system of an insect adapted for gas exchange?
- tracheole has thin wall: short diffusion pathway
- tracheoles enter tissues: short diffusion pathway
