Ventilation and gas exchange in other organisms 7.4 Flashcards
what about an insects anatomy/physiology provides a challenge to gasesous exchange and how has it evolved to overcome this
- have a tough exoskeleton, no gaseous exchange can take place here
- They don’t have any blood pigments that can carry oxygen
- has evolved to deliver the oxygen directly to the cells and to remove the carbon dioxide in the same way
- where are spircales found on the anatomy
- what is there function
- small openings along thorax and abdomen of insect
- respiratory openings where air can diffuse into and out of body of insect
How is water loss minimised by the insect related to spiracles
- sphincters at the end of the spiracles can open and close
^ allows water loss to be minimised and gas exchange to be maximised
When would the spiracles on an insect be open and when would they be closed
- during periods of high metabolic activity they will be open
^open when CO2 levels rise - during periods of low metabolic demand they are closed
along what does air travel as it makes it way past the spircales and into the body of the insect
brief description of structure and function
- tracheae
^ the largest tubes in insect respiratory system
^ carry air into the body.
Where would you find the tracheae in an insect
They run both into and along the body of the insect
what is the structure of tracheae in insects
- tubes lined with spirals of chitin (chitin makes up the cuctile)
^keep it open if bent or pressed. - relatively impermeable to gases (little gaseous exchange takes)
What does the tracheae divide into further into the respiratory system
- tracheoles (narrower tubes)
What is the structure of tracheoles and how does this aid there function
- narrow tubes
- single, greatly elongated cells
- no chitin lining so they are freely permeable to gases.
- due to small size they spread throughout the tissues/cells of the insects
Where does the majority of gas exchange actually take place in the insect
Most gas exchange takes place in the tracheoles that run throughout the insects tissues, along each cell
How does air usually move into the insects body for gas exchange
In most insects, for most of the time air moves along the tracheae and tracheoles by diffusion alone, reaching all the tissues
What can be done within the tracheoles in order to satisfy a high oxygen demand
At stable metabolic demand tracheal fluid limits surface area in tracheoles for gasesous exchange
At high metabolic demand, the presence of lactic acid causes fluid to move out via osmosis freeing up surface area to allow for greater gaseous exchange
How is the extent of gas exchange controlled in most insects
the extent of gas exchange in most insects is controlled by the opening and closing of the spiracles by the sphincters
What alternative methods of increasing the level of gaseous exchange have evolved in insects
air is pumped into tracheae via movements of the thorax and/or the abdomen.
These change the volume and so presusre of the respiratory system.
Air is drawn into the tracheae and tracheoles, or forced out as the pressure changes
This only evolved in insects with high energy demands such as bees and grasshoppers
what does DGC stand for
Discontinuous gas exchange cycles
they are relativly common for many species of insect
What are the 3 states of spircales in DGC
Open
Closed
Fluttering
what occurs in the closed state of the DGC
no gases move in or out of the insect.
Oxygen moves into the cells by diffusion from the tracheae and carbon dioxide diffuses into the body fluids of the insect (buffereing)
What occurs in the fluttering state of DGC
When the spiracles flutter, they open and close rapidly. This moves fresh air into the tracheae to renew the supply of oxygen, while minimising water loss.
what happens in the open state of DGC
When carbon dioxide levels build up really high in the body fluids of the insect, the spiracles open widely and carbon dioxide diffuses out rapidly. There may also be pumping movements of the Thorax and abdomen when the spiracles are open to maximise gaseous exchange
what do fish not need to worry about with there respiratory system
water loss since they live in water
what are the organs of gaseous exchange in fish
gills
in how many directions does water flow over the gills
water only goes in 1 direction over the gills
what adaptions do gills have that make them good exchange surfaces
brief
- large surface area
- good blood supply ( as to maintain a high concentration gradient)
- thin layers
- counter current system
- mucus coating to help trap oxygen
Where are the gills in most bony fish
In bony fish they are contained in a gill cavity
covered by a protective operculum (a bony flap)
What do fish need to do in order to allow efficient gas exchange at all time
maintain a continuous flow of water over the gills
what is ram ventilation
maintaining a constant flow of water over the gills to allow for the most efficent gas exchange in water via constant moving forward with your mouth open
what type of fish has to keep moving and cannot do the alternative method of water flow
The more primitive cartilaginous fish such as sharks and rays
what is the process of the alternative method of gill ventilation
part 1
mouth is opened and the floor of the buccal cavity (mouth) is lowered.
increasing volumemdecreasing pressure
water moves in
opercular valve is shut and the opercular cavity containing the gills expands.
This lowers the pressure in the opercular cavity containing the gills.
The floor of the buccal cavity starts to move up
increasing pressure so water moves over the gills
what is the process of the alternative method of gill ventilation
part 2
The mouth closes, the operculum opens and the sides of the opercular cavity move inwards. All of these actions increase the pressure in the opercular cavity and force water over the gills and out of the operculum. The floor of the buccal cavity is steadily moved up, maintaining a flow of water over the gills.
what unique adaptaions do gills have that allow them to best complete their function
Gill tips
tips of adjacent gill filaments overlap.
increasing resistance to flow of water over the gill surfaces so there is more time for gas exchange to occur
explain the countercurrent system and why it works
blood and water flow In opposite directions so an oxygen concentration gradient between the water and the blood is maintained all along the gill
allows frish to remove 80% of oxygen from water
what is the parallel system
opposite of current count system, blood and water move in same way so uptake of oxygen is less as concentration gradient is not maintained for long time are eventually is equalled
