ventilation and gas exchange in insects Flashcards
what does an insects circulatory system rely on
diffusion (not blood)
what does it mean if an insects circulatory system relys on diffusion
-it will be slow
-as a decreased diffusion rate as distance increases
what are the openings called to allow gas exchange and where are they found
-called spiracles
-found on the surface of the exoskeleton
what is the opening/closing of the spiracles controlled by and why
-muscular sphincters
-to minimise water loss
what are the tubes that the air moves through called (bigger and smaller ones)
-big tubes= tracheae
-smaller tubes= tracheoles
what are tracheoles
-single, elongated cells freely permeable to gases
-large surface area for gas exchange
-open ended
what is found at the ends of the tracheoles
tracheal fluid
what does gas exchange occur between
-the air in the tracheole and the insects respiring cells
-via diffusion
what is the tracheae reinforced with and why
-chitin
-to prevent collapsing during movement
what happens if the insects oxygen demand increases due to activity/ if lactic acid builds up from cellular anaerobic respiration
-lactic acid lowers the water potential of cells
-water in tracheal fluid moves into cells
-reduces volume in tracheae
-draws air into tracheae
-more surface area available for gas exchange
what methods do larger insects use for gas exchange
-air sacs with flexible walls
-altering volume of thorax using wing movement
-specialised breathing movements to alter volume of abdomen
how do larger insects use air sacs with flexible walls
-act as reservoirs
-can inflate/deflate
-regular muscle contractions of flight muscles can increase air moving in/out of air sacs so increasing rate of diffusion and supply of oxygen to respiring tissues via air moving into tracheoles
how do insects alter volume of thorax using wing movement
-contract flight muscles, volume of thorax decreases, air under higher pressure, air pushed out of tracheal system
-flight muscles relax, volume of thorax increases, air under lower pressure, air drawn into tracheal system
how do specialised breathing movements alter the volume of the abdomen
-as the abdomen expands the spiracles at the front of the body open and air enters tracheal system (mass transport of air)
-as the abdomen volume decreases: spiracles at the rear of body open air leaves the tracheal system
how do specialised breathing movements alter the volume of the abdomen (what are they coordinated with)
the opening/closing of valves in the spiracles
what happens when tracheal fluid withdraws due to lactic acid/higher respiration rates
-more of tracheole is exposed
-increased surface area available for gas exchange of o2 and co2 with surrounding cells
what type of process is the ventilation and gas exchange in insects
-mainly a passive process
-as oxygen and carbon dioxide diffuse down concentration gradients
what do the spiracles connect
-the tubes with the outside world
what prevents unwanted loss of water vapour
-muscular sphincters
how are tracheoles different from tracheae
they don’t have any spiral thickenings of chitin
what does the tracheal fluid at the end of tracheoles do
-slow down rate of oxygen uptake
-oxygen has to dissolve in the fluid before diffusing through it to reach respiring tissues
-during periods of relative inactivity
how does the use of air sacs increase rate of diffusion of oxygen
-increasing the oxygen concentration gradient between tracheole air space and respiring tissues
how does a one way flow occur
-opening front spiracles whilst keeping rear spiracles closed during intake of air
-opening rear spiracles and closing as air sacs empty
