7.4 Ventilation & Gas Exchange in Other Organisms Flashcards
Insects have evolved a gaseous exchange system which delivers + removes gases DIRECTLY from the cells. Why?
Insects do not have components which carry oxygen in haemolymph,
TOUGH EXOSKELETON prevents diffusion
What are the components of the gaseous exchange system in insects?
spiracles, tracheae, tracheoles, tracheal fluid
What are spiracles?
small OPENINGS along the ABDOMEN
which OPEN + CLOSE to regulate gas exchange + water loss
How are spiracles opened and closed?
using a sphincter
What are tracheae?
largest tubes of the insect respiratory system
What are tracheoles?
narrow tubes branching from tracheae.
site of gas exchange
What happens when oxygen demand/CO2 level is high in an insect respiratory system?
sphincter opens spiracles
air moves in but some water lost
Air travels through the spiracles into the tracheae. What are the features of tracheae?
CHITIN SPIRALS
provide support during air pressure changes
Does gas exchange occur in the tracheae?
no
lined by chitin spirals, which are IMPERMEABLE to O2 + CO2
Where are chitin spirals found?
tracheae only
Why is it important that tracheoles are not lined with chitin spirals?
chitin is impermeable to O2 + Co2
so gas exchange could not occur
What is the function of spiracles?
open + close to regulate gases in/out
How does gas exchange occur in insects?
spiracle is opened using sphincter,
air moves into trachea through spiracle,
air travels into tracheoles which have high total surface area + run between cells,
O2 diffuses into respiring cell + CO2 diffuses out
air outside ⟶ _____ ⟶ _____ ⟶ _____ ⟶ respiring cell
spiracle ⟶ tracheae ⟶ tracheole
What is the function of tracheal fluid?
LIMITS PENETRATION of air into tracheole.
as O2 demand ￪, more LACTIC ACID is produced,
decreases water potential of tracheal cell,
tracheal fluid moves into cell by osmosis,
air can penetrate further so more surface area for gas exchange
What is the structure of a tracheole?
each tracheole = 1 greatly ELONGATED cell without chitin lining
What are alternative methods for increasing the rate of gas exchange during times of high demand?
mechanical ventilation
collapsible tracheae
What is the mechanical ventilation and what is its purpose?
muscular pumping movement of abdomen/thorax
draws more air into tracheae
What is the purpose of collapsible tracheae?
increase volume of gas moving through gas exchange system
What is the operculum?
flap which MAINTAINS constant water flow over gills
which means bony fish do not have to be moving for gas exchange
What are gill filaments?
Thin flesh sheets
providing large surface area for diffusion
What are gill lamellae?
small folds on gill filaments
increase surface area + are site of gas exchange
What are gill plates?
stacks of gill filaments
How does the water flow in relation to the blood flow during gas exchange in a bony fish? What effect does this have?
countercurrent
prevents blood + water reaching equilibrium (from flowing in same direction), where no net diffusion occurs
