Gas Exchange In Single Celled Organisms And Insects Flashcards
What do the tracheae divide into
They are supported by strengthened rings to prevent them from collapsing. They divide into smaller dead end tubes called tracheoles
What do the tracheoles do
They extend through all the body tissues if the insect. In this way atmospheric air, with the oxygen. It contains is brought directly to the respiring tissues, as there is a short diffusion pathway from a tracheole to any body cell
In what way do respiratory gases move in and out of the tracheal system using a diffusion gradient
Along a diffusion gradient- when cells are respiring oxygen is used up and so it’s conc towards the ends of the tracheoles falls. Creating a diffusion gradient that causes gaseous oxygen to diffuse from the atmosphere along the trachea and tracheoles to the cells. Co2 is produced by cells during respiration, this creates a diffusion gradient in the opposite direction, this causes gaseous co2 to diffuse along the tracheoles and tracheae from the cells to the atmosphere
In what way do respiratory gases move in and out of the tracheal system using mass transport
The contraction of muscles in insects can squeeze the trachea enabling mass movements of air in and out
In what way do respiratory gases move in and out of the tracheal system using the ends of the tracheoles that are filled with water
Muscle cells around tracheoles respire carry out some anaerobic respiration. This produces lactate, it’s soluble and lowers water potential of the muscle cells. Water moves into the cells from the tracheoles by osmosis. The water in the ends of the tracheoles decrease in volume and in doing so draws air further into them - meaning the final diffusion pathway is in a gas rather then liquid phase and therefore diffusion is more rapid
How do gases enter and leave tracheae?
Through tiny pores called spiracles on the body surface
Why do insects keep spiracles closed
To prevent water loss, periodically they open the spiracles to allow gas exchange
What’s the limitations of the tracheal system
It relies mostly on diffusion to exchange gases, for it to be effective the pathway needs to be short, that’s why insects are smalll
Explain how the tracheal system limits the size of insects
As it relies on diffusion to bring oxygen to the respiring tissues. If insects were large it would take too long for Oxygen to reach the tissues rapidly enough to supply their needs
