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Biology - mr ellis > module 3 - 7.4 ventilation and gas exchange in other organisms > Flashcards

module 3 - 7.4 ventilation and gas exchange in other organisms Flashcards

1
Q

what is the top part of an insects anatomy called?

A

head

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2
Q

what is the middle part of an insects anatomy called?

A

thorax - (legs and wings attached to thorax)

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3
Q

what is the end part of an insects anatomy called?

A

abdomen

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4
Q

where are the tracheal tubes located in an insect?

A

the thorax

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5
Q

why does an insect have a problem overcoming losing water with their gas exchange organs?

A
  • they are land dwelling with high demand of O2 and CO2 removal
  • SA:V too small for diffusion for removal
  • hard exoskeleton prevents diffusion to outer surface
  • separate circulatory and gas exchange systems
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6
Q

what are spiracles?

A
  • holes in the thorax and abdomen walls - a pair for each segment of body
  • often with valves
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7
Q

what are tracheae?

A

tubes that lead into the body from the spiracles, form branching pattern of smaller diameter tubes

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8
Q

what are tracheae strengthened by?

A

hoops or spiracles of chitin called taenidia

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9
Q

what are tracheoles?

A
  • single, greatly elongated cells that form minute tubes
  • found at ends of smallest tracheae
  • site of gas exchange with body cells
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10
Q

what is tracheal fluid?

A

fluid in the very end of tracheoles

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11
Q

what are valves?

A

they have control over gas exchange surfaces

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12
Q

what is the movement of air in insects?

A
  • air enters & leaves insects through spiracles
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13
Q

why can spiracles be opened/closed?

A

to reduce water loss by contracting muscles surrounding spiracle that opens valves in the spiracle

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14
Q

why are spiracles surrounded by hairs?

A

to minimise bulk air movement around the opening to reduce water loss

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15
Q

when are spiracles opened/closed?

A

depending on metabolic demands of the insect
- when inactive, spiracles are mainly closed as demand for oxygen is lower

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16
Q

what happens after the air has passed through the spiracles?

A

it enters an air complex, branching network of tracheal tubes that divides into smaller diameters - reaches every part of the body

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17
Q

what prevents collapse of trachea under pressure?

A

a thin, reinforcing ‘wire’ of chitin winds spirally through wall or hoops in wall

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18
Q

what does the spiral of chitin allow for the tracheal tubes?

A

gives ability to flex and stretch without developing kinks that may restrict air flow

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19
Q

why do tracheoles penetrate into the spaces between body cells?

A

creates large SA so gas exchange can meet metabolic demands

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20
Q

why do tracheoles have no chitin and thin walls?

A

to create a smaller diffusion distance

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21
Q

why is the inside wall of tracheoles moist with water?

A

so oxygen can dissolve into liquid phase along moist lining & diffuse into body cells, CO2 follows reverse path

22
Q

where does tracheal fluid fill and what happens to the air because of this?

A

fills very ends of tracheoles, air cannot penetrate further, gas exchange by diffusion still occurs in body cells

23
Q

what do small insects entirely rely on to ventilate the tracheal system?

A
  • passive diffusion of gases
  • physical movement of the insects body
24
Q

what do larger insects require to ventilate the tracheal system?

A
  • active ventilation
  • done by opening some spiracles and closing others while using abdominal muscles to expand/contract body volume
25
Q

what does the opening of some spiracles and closing others while using abdominal muscles create?

A

creates pulsating movements that fresh air from one end of the body to the other through the tracheal system

26
Q

what are the main limiting factors affecting ventilation?

A
  • rate of gas diffusion
  • weight of exoskeleton (limits size of insects)
27
Q

what do the air sacs in some insects act as?

A

reservoirs of air and conserve water during drought period
- aquatic insects use them to regulate buoyancy

28
Q

when do discontinuous gas exchange cycles occur?

A

when insects are at rest and may help insects by preventing entry of pathogens through spiracles

29
Q

what are the 3 phases of discontinuous gas exchange cycles that reflect the behaviour of spiracles?

A
  • closed phase
  • open phase
  • flutter phase
30
Q

what is the closed phase (CP)?

A
  • spiracles shut tight
  • reduces ventilation with external environment
  • O2 consumed, concentration decreases
  • CO2 buffered at haemolymph - leads to negative pressure and starts flutter phase
31
Q

what is the flutter phase (FP)?

A
  • spiracles open slightly & close rapidly
  • negative pressure in CP causes little air from environment to enter respiratory system when spiracles open
  • fresh air brought into tracheal system to increase conc. of O2 & release CO2 (still buffered by lymph)
32
Q

what is the open phase (OP)?

A
  • flutter phase continues until CO2 production surpasses buffering capacity of haemolyph (builds up within tracheal system)
  • rapid release of CO2
  • complete exchange of gases with environment by diffusion
33
Q

why do insects have discontinuous gas exchange cycles?

A

to stop them losing water

34
Q

how many gills do fish typically have?

A

5

35
Q

why do bony fish have no difficulty losing water with their gas exchange organs?

A

because they are in water

36
Q

why is the SA:V too small in fish?

A

they tend to be large, active animals, SA:V too small to allow to supply their need of O2 & removal of CO2

37
Q

what do fish scales and their outer slime layer prevent?

A
  • diffusion
  • slime layer adds protection, allows faster movement
38
Q

what type of flow do fish gills employ?

A

counter current flow

39
Q

what are 3 evolutionary strategies to gas exchange in fish?

A
  • obligate air breathers (have to breathe)
  • facultative air breathers (mainly use gills but can breathe air)
  • gills (cannot breathe air)
40
Q

what is the operculum (gill cover)?

A
  • a series of bones that act as facial support and protective gill covers
  • it adjusts pressure of water inside pharynx to allow ventilation
41
Q

what is the buccal cavity?

A
  • bony fish inhale water through their mouth by lowering floor of buccal cavity & closing opercular valves
  • exhale by closing mouth, raising floor of buccal cavity, and open opercular valves to get water out
42
Q

what are gill arches?

A

series of bony loops that support gills

43
Q

what are gill rakers?

A

bony or cartilaginous processes that project from the branchial arch

44
Q

what are gill filaments?

A

occurs in large stacks, each stack is a gill plate

45
Q

what are gill lamellae?

A
  • main site of gas exchange in gills
  • very large SA
  • good blood supply
  • thin, moist walls
46
Q

what are the standard exchange surface features of fish?

A
  • large SA to allow enough O2 & CO2 exchanged with water
  • good blood supply to maintain concentration gradients of O2 & CO2
  • thin walls so diffusion pathway is short
47
Q

what 2 extra features allow gills to overcome problems of gas exchange in water?

A
  • tips of adjacent gill filaments overlap to slow flow of water, allows more time for gas exchange
  • water moving across and through gills & blood flowing in gill filaments go in opposite directions
48
Q

what is counter current flow?

A

when water moving across and through gills & blood flowing in gill filaments go in opposite directions

49
Q

what is the parallel system?

A
  • occurs in cartilaginous fish
  • blood in gill filaments and water across & through gills move in same direction
  • oxygen diffuses down steep conc. gradient, equilibrium reached at some point
  • surface area of gill filaments not being fully utilised for O2 exchange between water and blood
  • less efficient than counter current flow
50
Q

what is the counter current flow system?

A
  • occurs in bony fish
  • blood in gill filaments and water moving across gills goes in opposite directions
  • oxygen diffuses down conc. gradient along whole length of gill filaments, equilibrium never reached
  • entire surface of gill filaments fully utilised

Biology - mr ellis (76 decks)

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