Ventilation and gas exchange in other organisms Flashcards
Do insects have a high or low metabolic rate?
High
Do insects usually have blood pigments?
No
What does the insects tough exoskeleton prevent?
Gaseous exchange
What are along the thorax and abdomen of most insects?
small openings called spiracles
What do the spiracles do?
Air enters and leaves the system through the spiracles.
How can the spiracles be opened and close?
Via sphincters
Why are the spiracle sphincters kept closed as much as possible?
To minimise water loss.
What happens to the spiracles when the insect is inactive and oxygen demands are low?
They are kept closed.
What happens to the spiracles when the oxygen demand is raised or the carbon dioxide levels build up?
More of the spiracles open.
What is extended after the spiracles?
The trachea
How big is an insects trachea?
1mm in diameter
What does the trachea do?
Carry air into the body
What is the trachea lined with?
Spirals of chitin
What is chitin?
The material that makes up the cuticle. It is relatively impermeable to gases and so little gaseous exchange takes place in the trachea.
What does the trachea divide into?
Narrow tubes called tracheoles.
How large are tracheoles?
0.6-0.8 m
What is the structure of the trancheoles?
Each trancheole is a single, greatly elongated cell with no chitin lining so they are freely permeable to gases.
Were does most of the gaseous exchange take place?
Between the air and the respiring cells.
What does the vast number of the tracheoles give the insect?
A very large surface area.
What is towards the end of the tracheole?
The tracheal fluid!
What does the tracheal fluid do?
The tracheal fluid limits air diffusion.
Large insects such as bees, wasps and flies have high energy demands. To increase the level of gaseous exchange, these insects have special techniques. What are they?
Mechanical ventilation of the tracheal system Collapsible enlarged trachea or air sacs
How does mechanically ventilating the tracheal system provide a higher level of gaseous exchange?
Air is pumped into the system via muscular pumping movements of the thorax and/or the abdomen. This changes the volume of the body and thus the pressure in the trachea and trancheoles. As the pressure changes in the insects body, the air is drawn into the trachea and tracheoles, or out.
How does collapsing enlarged trachea or air sacs provide a higher level of gaseous exchange?
They act as air reservoirs and are used to increase the amount of air moved through the gas exchange system. They are usually inflated and deflated by the ventilating movements of the thorax and abdomen.
What are the fishes organs for gaseous exchange?
The gills
Where are the gills located in bony fish?
In the gill cavity
What are the gills covered by?
Operculum (a bony flap that you cut of during dissection) :)
What does the operculum do?
Maintains a flow of water over the gills
Is diffusion faster in water or air?
Air
How do the gills increase the rate of gaseous exchange?
They contain… A good blood supply A large surface area Thin layers
In order to ventilate the gills, some fish (such as sharks) rely on continual movement. What is this known as?
Ram ventilation (They just ram the water past the gills)!
In order to ventilate the gills, some fish (such as sharks) rely on continual movement. What is this known as?
Ram ventilation (They just ram the water past the gills)!
Most bony fish rely on what to keep water flowing over the gills?
The operculum
Describes the steps for inhalation for a fish
The fish opens the mouth and the floor of the buccal cavity is lowered. This increase the volume of the buccal cavity, and thus the pressure is lowered which causes the water to rush into the buccal cavity. The opercular valve shuts and the opercular cavity containing the gills expands. This lowers the pressure the the opercular cavity containing the gills. The floor of the buccal cavity moves up and the mouth closes. This increases the pressure in the buccal cavity and the water rushes over the gills.
Describe the steps of exhalation for a fish
When the mouth closes the operculum opens and the sides of the opercular cavity move inwards. This increases the pressure in the opercular cavity and thus forces the water out and over the gills.
What are the two extra adaptions that fish have for an even more efficient gaseous exchange?
The tips of the gill filaments overlap. The water moving over the gills and the blood in the gill filaments flow in a different direction.
Why is it good that the gill filaments overlap?
It increases the resistance to the flow of water so that it slows down, so that there is more time for gaseous exchange.
Why is it important that the the water moving over the gills and the blood in the gill filaments flow in a different direction?
Because a steep concentration gradient is needed for for fast and efficient gas diffusion. When the water and the blood flow in different directions a countercurrent exchange system is created which maintains a high concentration gradient. As a result more gaseous exchange can take place.
Why is it important that the the water moving over the gills and the blood in the gill filaments flow in a different direction?
Because a steep concentration gradient is needed for for fast and efficient gas diffusion. When the water and the blood flow in different directions a countercurrent exchange system is created which maintains a high concentration gradient. As a result more gaseous exchange can take place.
What percentage of oxygen is removed from the water with fish with countercurrent systems?
80%
What percentage of oxygen is removed from the water with fish with parallel systems?
50%
