3.1.5 gas exchange in other organisms (bony fish & insects) Flashcards
(fish) buccal cavity
mouth
(fish) countercurrent flow
2 fluids flow in opposite directions
(fish) describe filaments
- what can they also be called
slim branches of tissue that make up the gill
(primary lamellae)
(fish) describe lamellae
—> what can these also be called
folds of filament to increase surface area
—> often called secondary lamellae or gill plates
(fish) operculum
bony flap that covers/protects gills
(insect) spiracle
pore that allows air in/out of tracheae
(insect) tracheal fluid
fluid found at ends of tracheoles in tracheal system
(insect) tracheal system
system of air-filled tubes
how do bony fish exchange gases
using gills to absorb oxygen dissolved in water & release carbon dioxide into water
how many pairs of gills do most bony fish have
5
what does each gill consist of
2 rows of gill filaments attached to bony arch
describe the gill filaments
- very thin
- surface folded into many secondary lamellae (gill plates) = large surface area
how does exchange occur in bony fish
capillaries carry deoxygenated blood close to surface of secondary lamellae
describe the dissection of a fish gill
- find operculum
- lift operculum to observe gills/colour
- cut away one operculum
- cut out one gill
describe the countercurrent flow in bony fish
- blood flows along gill arch & along filaments to secondary lamellae
- then blood flows through capillaries in opposite direction to flow of water over the lamellae
what does the countercurrent flow achieve
- maintains high conc. gradient
- absorbs max. amount of oxygen from water
describe the process of ventilation in a bony fish
- fish opens mouth & lowers floor of buccal cavity
- increases volume & decreases pressure in buccal cavity
- water’s drawn into mouth
- mouth closes & floor of buccal cavity is raised
- decreases volume & increases pressure in buccal cavity
- water’s pushed from buccal cavity which causes operculum to move outwards = reducses pressure in opercular cavity which helps water flow through the gills
what type of circulatory system do insects have & what does that mean
open circulatory system
= body fluid acts as both blood/tissue fluid
what do insects possess
air-filled tracheal system = supplies air directly to all respiring tissues
how does air enter the tracheal system
via a pore in each segment (spiracle)
how is air transported into the body
- through series of tubes called tracheae
- these divide into smaller tubes called tracheoles
- ends of tracheoles are open & filled with fluid (tracheal fluid)
where does gaseous exchange occur in an insect
between air in tracheole & tracheole fluid
—> some can occur across thin walls of tracheoles
what can happen when insects/the tissues are active
- tracheal fluid can be withdrawn into the body fluid —> increase surface area of tracheole wall exposed to air
= more oxygen can be absorbed when insect is active
how can larger insects also ventilate their tracheal system
- how many ways can this be achieved
movements of the body
—> 3 ways
summarise the 3 ways larger insects can ventilate their tracheal system by movements of the body
- sections of tracheal system are expanded/flexible walls - act as air sacs which can be squeezed by action of flight muscles —> repetitive expansion/contraction = ventilate tracheal system
- movements of wings alter volume of thorax - thorax vol decreases = air in tracheal system under pressure & pushed out - thorax vol increases = pressure inside drops & air pushed into tracheal system from outside
- locusts can alter vol of abdomen by specialised breathing movements - coordinated with opening/closing valves in spiracles —> as abdomen expands = spiracles at front of body open & air enters tracheal system —> abdomen reduces in vol = spiracles at rear end open & air can leave tracheal system
