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BIO224 - ichthyology > respiration > Flashcards

respiration Flashcards

1
Q

what is cellular respiration

A

The chemical process by which cells obtain energy from molecules such as glucose

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2
Q

what is physiological respiration

A

Uptake of oxygen from the environment and its distribution to the tissues of the body

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3
Q

what is the biggest respiratory challenge fish face compared to humans

A

obtaining sufficient oxygen to fuel metabolism - 200 ml O2 L-1 air , 0.04 - 12 ml O2 L-1 water

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4
Q

what happens to O2 conc as Temperature or Salinity increases

A

decreases

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5
Q

what are the 2 problems face fish during respiration

A
  1. Get water to the gills (ventilation)
  2. Extract oxygen from the water
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6
Q

how do fish Extract oxygen from the water

A

by using their gills (multipurpose organs)

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7
Q

what 4 things are gills used for

A

Aquatic gas exchange
Osmotic and ionic regulation
Acid-base regulation
Excretion of nitrogenous waste

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8
Q

how do the gills mainly function

A

via diffusion (although some specialised mechanisms also exist, e.g. for osmoregulation).

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9
Q

how many gill arches do teleosts and elasmobranchs have

A
  • Normally 4 gill arches on either side of head in teleosts
  • 5 in elasmobranchs (more variable)
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10
Q

what are gill arches

A

Bony – each one carries 2 rows of filaments

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11
Q

what are gill rakers

A

Projections that act like a siv – stop damage to the filaments

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12
Q

what are gill filaments

A

Sight of gaseous exchange – filled with blood, water runs across them – stiffened with internal bony ray
- each filament carries leaf-like lamellae positioned parallel to water flow - maximises surface area

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13
Q

what is counter current flow

A

Maintains diffusion gradient for entire length of blood vessel – 100% transfer efficiency – blood always encounters water with higher O2 concentration
- Venous blood (entering) encounters water that has had most of the O2 taken out of it by the gills, but NOT all of it – still has more O2 than the blood

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14
Q

what is Concurrent flow

A

blood and water go in same direction – 50% transfer efficiency

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15
Q

2 things that maximise gas transfer

A
  • Lamellae interleaved with adjacent filaments – maxamises surface area
  • thin lamellae epithelium wall (2-4um) - short distance to maximise transfer
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16
Q

what kind of circulatory system do fish have

A

Single circulatory system - Venous blood comes into the heart, gets pumped to gill, around the body, then back to heart

17
Q

function of the bulbus Arteriosus

A

where blood pumps out of the heart
Evens out the flow – allows consistant pressure

18
Q

what part of the heart collects the blood

A

sinus venosus

19
Q

why is getting water into the gills a problem

A

water = more viscous

20
Q

what are the 2 types of ventilation

A

Ram ventilation (passive)
Buccal ventilation (active)

21
Q

what is ram ventilation

A
  • Forward swimming that forces water through the mouth, exits at operculum (gill-slits in sharks) - Usually for fish that swim all the time
  • Creates some drag, otherwise doesn’t require any muscular work (passive)
  • Superb mechanism – the faster you go, the greater your oxygen demand but the more efficient you are at extraction
22
Q

what is Buccal ventilation

A
  • Actively pumping water over the gills – muscular contraction costs energy
  • Sharks can use this method of ventilation
  • Some fish ram ventilate AND buccal ventilate (many sharks and some larger teleosts e.g. mackeral)
23
Q

explain the buccal ventilation process

A
  1. Buccal cavity (BC) increases, water drawn in through mouth
  2. Fraction later opercular cavity (OC) increases but opercular valve (OV) stays closed, so OC acts like suction pump and draws water across gill
  3. Mouth closes, buccal cavity (BC) contracts and acts like pressure pump forcing water over gills
  4. Fraction later opercular cavity (OC) contracts forcing water out of opercular valve (OV) (or gill slits in sharks)
  5. Cycle starts again
    **A pressure gradient is maintained across gills, keeping a UNIDIRECTIONAL flow of water aka there is no backflow of water across the gills
24
Q

explain Aerial respiration (air breathing)

A
  • Done by lots of freshwater fish
  • Use an accessory organ – can be many different things e.g. modified gills/stomach (catfish), cheek (electric eel), rectum (loach)
  • A lot of primitive fishes that gulp air use a modified swim bladder e.g. lungfish, bowfin
  • Allow fish to leave water or live in hypoxic environments
25
Q

how does More activity ensure they require more oxygen

A

Increasing stroke volume (more water per pump)
Increasing stroke rate (more pumps per minute)
**this decreases time water in contact with gill (from 250ms at rest to 30ms at speed)

26
Q

what is the Short-term control of gill area affected by

A

release of adrenalin to accommodate different activity levels

27
Q

what long term / evolutionary physiological and morphological adaptations can highly active fish show

A
  • most obvious = dramatically increased gill surface area
  • Also can reduce thickness barrier between blood and water – faster diffusion
  • ram ventilate – the faster you go, the more contact time reduces between lamellae and a “unit” of water aka the quicker the water goes in and out of the gills – means a larger concentration gradient -> higher diffusion (rate of diffusion depends on difference in concentration)
28
Q

Adaptation for ram ventilation in teleosts

A
  • Contains filament fusions too – enhances strength
  • Also decreases surface area – used by really fast fish - don’t need the large surface area as thy rely on ram ventilation completely
29
Q

respiration features for low aerobic fish

A
  • thick blood barrier
  • small gill SA
  • buccal ventilation
30
Q

heat characteristics of fish

A
  • Ectothermic - rely on external heat source
  • Poikilothermic - variable body temperature
  • but regional ENDOthermy has evolved independently in several lineages of marine fishes, including lamnid sharks, tunas and billfishes
31
Q

heat characteristics of mammals

A
  • Endothermic use an internal heat source
  • Homiothermic maintain a constant body temperature
32
Q

what is The rete mirabile

A
  • “Wonderful net”
  • Based on principal of maintaining the concentration gradient between contents of adjacent capillaries (arterioles and venules)
  • It utilises principal of countercurrent flow
  • Gills are NOT a rete mirabile
33
Q

what does A rete mirabile rely on

A

Small diameter capillaries, with very thin walls, all packed tightly together, with arterioles and venules adjacent to one another
- There may be over 200,000 capillaries in a rete mirabile - That’s equivalent to 1,000 m2 diffusional area (17 times larger diffusional area than in a human lung)

34
Q

what does Retia mirabilia in fish entail

A
  • Oxygen multiplication in the retina + swimbladder
  • Heat multiplication in scombrid + lamnid shark muscle
  • Fish can’t be truly endothermic – can’t control heat loss across gills – but can keep the heat somewhere
35
Q

explain Retia mirabilia in fish

A
  1. Blood going across the gills gets cooled by water around it
  2. Blood goes across postcardinal vein – makes whole body cold
  3. Endothermic fish also have lateral blood vessels (on the side) - these run through retina mirabilia before getting to the swimming muscles
  4. Warm blood going into swimming muscles runs next to the cold blood running in, warming the blood up – maintains a warm part of the body
    - need to move the swimming muscle for this to work – swimming muscles are moved into the body away from the surrounding water in endotherms e.g. all tuna
36
Q

examples of what Retia mirabilia is used for in other animals

A
  • To reduce heat loss in legs of wading birds, arctic wolves, caribou and other cold climate homiotherms
  • Reduce heat loss in flippers of marine mammals
  • Prevent overheating in brain of some hoofed mammals and small carnivores (e.g. cats and dogs)
  • Prevent overheating in mammalian testes (used as cooling device rather than heating)
37
Q

Advantages of endothermy

A
  • Mammal like muscle power - red muscle of tuna is stenothermic (better stamina + strength)
  • Increased digestive efficiency (enzyme activity dependent on temperature)
  • Increased ability to see in the deep-dark ocean (Orbital rete miribile e.g. big-eye thresher, swordfish
  • Allow niche expansion

BIO224 - ichthyology (13 decks)

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