Ventilation and gas exchange in other organisms Flashcards
(41 cards)
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.
