exchange surfaces- ventilation and gas exchange in other organisms Flashcards
what are spiracles?
small openings along the thorax and abdomen of most insects.
How does gas exchange take place in insects?
air enters and leaves the system through spiracles. Water is also lost through spiracles therefore to minimise water loss but maximise efficiency of gas exchanges sphincters are closed as much as possible.
What are sphincters?
spiracles can be open or closed by sphincters
what occurs to the spiracles when the insect is inactive?
oxygen demands are low and the spiracles will be closed most of the time.
what occurs the spiracles when the oxygen demand is raised or the carbon dioxide levels build up?
spiracles open
Describe the trachea of the gas exchange system in insects?
spiracles lead to trachea which carry air to the body which are lined with spirals of chitin. These keep the tubes open if they are bent or pressed. Chitin makes up the cuticle. It is impermeable to gases so little gas exchange happens in the trachea.
what does trachea branch into?
trachea branches into narrower tubes called tracheoles. Each tracheole is a single greatly elongated cell with no chitin lining so it is freely permeable to gases. Because of their small size, they can spread through cells of tissue where most gas exchange takes place.
How has the gas exchange system adapted?
-vast numbers of tiny tracheoles create great surface area for gas exchange
-oxygen dissolves in moisture on walls of tracheoles and diffuses to surrounding cells.
-tracheal fluid at the end of tracheoles limit penetration of air for diffusion.
what happens to maximise surface area when oxygen demands increase (e.g when flying)?
water moves out tracheoles through osmosis which provides more surface area for gaseous exchange.
extend of gaseous exchange in most insects is controlled by?
the opening and closing of spiracles
how does mechanical ventilation increase levels of gaseous exchange in insects with high oxygen demand?
-mechanical ventilation of the tracheal system: muscular pumping movements of thorax and abdomen actively pump air into system. These movements changes volume of body and changes pressure in trachea and tracheoles causing air to be drawn in or forced out.
How do insects with high energy demand, needing extra oxygen, increase their levels of gaseous exchange?
mechanical ventilation and collapsible enlarged trachea or air sacs which act as air reservoirs.
How does collapsible enlarged trachea or air sacs which acts as air reservoirs increase levels of gaseous exchange in insects with high oxygen demand?
these are used to increase the amount of air moved through the gaseous exchange system. They are usually inflated and deflated by the ventilating movements of the thorax and abdomen
why do spiracles flutter, open and close rapidly?
this moves fresh air into the trachea to renew the supply of oxygen while minimising water loss-discontinuous gas exchange
how have the gills adapted to provide efficient gaseous exchange?
-bony fish maintain a flow of water in one direction over the gills.
-larg surface area
-good blood supply
-thin layers
-gill cavity covered by operculum which is active in maintaining a flow of water over the gills.