Gaseous exchange in other organisms Flashcards
Why do insects need a different gas exchange system?
Tough exoskeleton –>little exchange can take place
No blood pigments that carry O2
What is a spiracle?
Allows gases/water vapour to leave/enter.
Controlled by sphincters
Open when active (allows O2)
Closes at rest (prevent water loss)
Function of the tracheae?
Carries air into the thorax
Lined with chitin
~~~> impermeable to gases
~~~> structural support for tracheae
Function of tracheoles?
Individual elongated cells
No chitin –> permeable to gas exchange
Increase SA
What happens when insect is at rest?
Tracheoles lined with tracheal fluid.
~~> Limits air penetration.
High water potential
What happens when insect is active?
More anaerobic respiration.
More lactic acid
Tracheal fluid moves out of tracheoles via osmosis
More SA for diffusion
What are some features in larger insects?
*Mechanical ventilation in tracheal system
~~>air actively pumped by muscular pumping of thorax/abdomen.
Changes volume .:pressure
Air drawn in/forced out.
*Collapsible enlarged tracheae/air sacs
~~> act as reservoirs.
–> increase amount of air moved through exchange system.
Why do fish have a different gas exchange system?
Water = more viscous + dense than air
Slow rate of diffusion.
Too much energy to move water in/out
Counter current system.
Where does gas exchange occur?
Gill lamellae –> rich blood supply + large SA.
For efficient gas exchange –> continuous flow of water over the gills.
What happens when mouth of fish opens.
Buccal cavity lowered
Increases volume of buccal cavity.
Decreases pressure
Water moves in.
Opercular valve = shut
Opercular cavity with gills expands.
Lowers pressures in opercular cavity
Water moves from opercular cavity across gills down concentration gradient.
What happens when mouth of the fish closes?
Buccal cavity raised.
Volume decreases
Pressure increases
Water flows out of buccal cavity and flows over gills.
Pushes operculum open.
Describe the counter current system in gas exchange?
Water moving over gills and blood in gill filaments move in different directions.
Steep concentration gradient.
More gas exchange can take place.
Why is the tips of adjacent gill filaments overlapping an adaptation?
Increases resistance to flow of water over gill surface.
Slows down movement of water.
More time for gas exchange to take place.
