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fish > midterm 1 > Flashcards

midterm 1 Flashcards

1
Q

jawless fish are called

A

agnathans

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2
Q

cartilaginous fish are called

A

chondrichthyes

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3
Q

bony fish are called

A

osteoichthyes

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4
Q

fish taxonomy is based on:

A
  • anatomical characteristics
  • meristic characters
  • morphometrics
  • differences in DNA
  • behaviour/physiology
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5
Q

mouth positioned on bottom of head

A

inferior

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6
Q

mouth positioned around chin

A

subterminal

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7
Q

mouth positioned at front of head

A

terminal

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8
Q

mouth positioned above head

A

superior

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9
Q

upper and lower portions of tail ~same size

A

homocercal

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10
Q

homocercal tail without defined lobes

A

isocercal

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11
Q

one lobe longer than the other lobe

A

heterocercal

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12
Q

tail looks homocercal but vertebrae are heterocercal

A

abbreviate heterocercal

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13
Q

segmented, branched rays

A

soft rays

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14
Q

undivided, solid rays

A

spinous rays

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15
Q

thick bony plates that occur in one to a few rows and cover a limited amount of the body ex. sturgeon

A

scutes

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16
Q

consists of a basal plate buried in the dermis and a raised spiny process. comprised of bone, similar to a tooth, outer layer of enamel ex. sharks

A

placoid

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17
Q

thick rhomboid shaped bony scales like a suit of armour. enamel composed of ganoine ex. gar

A

ganoid

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18
Q

round flat and thin scales found on bony fish ex. trout, minnows, herring

A

cycloid

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19
Q

similar to cycloid but with comb-like projections (ctenii) on posterior (exposed) part of the scale. found in spiny-finned teleosts

A

ctenoid

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20
Q

what are ptergiophores

A

bone structure that supports and articulates unpaired fin rays

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21
Q

what are the pelvic and pectoral girdle

A

bone structures that support paired fins

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22
Q

all fish are in phylum:

A

chordata

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23
Q

all fish are in subphylum:

A

craniata

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24
Q

hagfish are in infraphylum, class, and order:

A

myxinomorphi, myxini, myxiniformes

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25
Q

lamprey are in infraphylum, superclass, class, order:

A

vertebrata, petromyzontimorphi, petromyzontida, petromyzontiformes

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26
Q

hagfish and lamprey characteristics

A
  • jawless
  • lack paired fins
  • no scales
  • cartilaginous skeleton
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27
Q

hagfish characteristics

A
  • no vertebrae
  • burrow
  • detritivore
  • produce mucous
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28
Q

lamprey characteristics

A
  • some parasitic
  • rudimentary vertebrae
  • complete braincase
  • eat living organisms
  • migrate from ocean to river to spawn
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29
Q

superclass and class of cartilaginous fish:

A

gnathostomata, chondrichthyes

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30
Q

6 unique features of chondrichthyes

A
  • cartilaginous skeleton
  • internal fertilization
  • well developed electrosensory systems
  • unsegmented fin rays
  • teeth not embedded in jaws
  • spiral valve in intestine
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31
Q

what does the spiral valve do

A

increase surface area for absorption

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32
Q

chimaera superorder and order

A

holocephalimorpha, chimaeriformes

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33
Q

chimaera characteristics

A
  • long slender tail
  • pointed head
  • fleshy operculum covering gilles
  • upper jaw fused to cranium
  • no scales
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34
Q

shark rays and skates infraclass

A

elasmobranchii

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35
Q

elasmobranchii characteristics

A
  • heterocercal tail
  • 5-7 fill slits
  • upper jaw not fused to cranium
  • placoid scales
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36
Q

bony fish class

A

osteichthyes

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37
Q

lobe-finned fish subclass

A

sarcopterygii

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38
Q

coelacanth subclass, infraclass, and order

A

sarcopterygii, actinistia, coelocanthiformes

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39
Q

lungfish subclass, infraclass, order, 3 families

A

sarcopterygii, dipnomorpha, ceratodontiformes, [neoceratodontidae, lepidosirenidae, protopteridae]

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40
Q

australian lungfish family

A

neoceratodontidae

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41
Q

south american lungfish family

A

lepidosirenidae

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42
Q

african lungfish family

A

protopteridae

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43
Q

lungfish characteristics

A
  • freshwater
  • breathe air
  • have a true lung
  • live in ephemeral areas
  • estivate
  • drown if they can’t use lung
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44
Q

ray-finned fish subclass

A

actinopterygii

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45
Q

bichir and reedfish subclass, infraclass, and order

A

actinopterygii, cladistia, polypteriformes

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46
Q

bichir and reedfish characteristics

A
  • dorsal fin a series of finlets
  • pectoral fin lobate
  • ganoid scales
  • modified swim bladder lung
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47
Q

sturgeon and paddlefish subclass, infraclass, and order

A

actinopterygii, chondrostei, ascipenseriformes

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48
Q

sturgeons and paddlefish characteristics

A
  • cartilaginous skeleton
  • 5 rows of bony scutes
  • heterocercal tail
  • spiral valve
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49
Q

amia calva infraclass, division, and order

A

neopterygii, halecomorphi, amiiformes

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50
Q

amia calva characteristics

A
  • abbreviate heterocercal
  • gular plate made of bone on underside of head
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51
Q

gar infraclass, division, and order

A

neopterygii, ginglymodi, lepisosteiformes

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52
Q

gar characteristics

A
  • ganoid scales
  • abbreviate heterocercal tail
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53
Q

advanced bony fish infraclass and division

A

neopterygii, teleosteomorpha

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54
Q

improvements that contributed to telostean success

A
  • reduction of bony elements
  • dorsal fin becomes elongate and diversified
  • pectoral fins move up to side of body
  • pelvic fins move forward to thoracic or jugular
  • increase in symmetry
  • added control over gas bladder function
  • more protrusible mouth
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55
Q

defining feature of teleosts

A

development of hypural and uroneural bones in the caudal fin

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56
Q

4 ways fish move

A
  • passive drift
  • walk or crawl
  • aerial locomotion
  • swimming
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57
Q

what is passive drift

A
  • simplest form of movement
  • mostly used by larvae and during migration
  • follow current
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58
Q

how do fish walk or crawl?

A
  • use pectoral and/or pelvic fins to pull themselves
  • fins with strong spines
  • ex. walking catfish, mudskippers
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59
Q

how do fish fly?

A
  • jumping up waterfalls
  • gliding/flapping flight
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60
Q

how do fish swim?

A
  • sides of body and fins exert force on water through muscular contraction
  • muscular contraction bends the body
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61
Q

what do fish have to overcome to swim?

A
  • frictional (viscous) drag: between fish body and water
  • pressure/inertial drag: pressure differences from displacement of water as fish swims
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62
Q

7 types of median and paired fin propulsion

A
  • tetraodontiform
  • balistiform
  • diodontiform
  • rajiform
  • amiiform
  • gymnotiform
  • labriform
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63
Q

tetradontiform propulsion

A

anal and dorsal fins moved simultaneously in one direction, oscillatory

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64
Q

balistiform/diodontiform propulsion

A

use of median fins intermediate between oscillation and undulation. diodontiform also use pectoral fins

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65
Q

rajiform propulsion

A

undulation of pectoral fins

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66
Q

amiform propulsion

A

undulation of dorsal fin

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67
Q

gymnotiform propulsion

A

undulation of anal fin

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68
Q

labriform propulsion

A

oscillation of pectoral fins

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69
Q

5 types of body and caudal fin propulsion

A
  • anguilliform
  • subcarangiform
  • carnagiform
  • thunniform
  • ostraciform
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70
Q

anguilliform propulsion

A

all but the head contributes to propulsion

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71
Q

subcarangiform propulsion

A

undulations restricted to posterior half of the body

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72
Q

carangiform propulsion

A

undulation restricted to posterior third of the body

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73
Q

thunniform propulsion

A

only caudal peduncle and caudal fin involved

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74
Q

ostraciform propulsion

A

all thrust from caudal fin, oscillatory propulsion

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75
Q

body and caudal fin propulsion is powered by what

A

trunk musculature

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76
Q

trunk musculature consists of a series of:

A

vertical muscle blocks called myomeres or myotomes separated by sheets of connective tissue called myosepta

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77
Q

general location of red muscle

A

along the lateral line parallel to the body’s axis

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78
Q

general location of white muscle

A

comprises most of the muscle, “bent” by as much as 45 degrees

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79
Q

explain length tension curve

A

tension increases as sarcomere length shortens until it reaches the area in the middle with no myosin heads and stays constant. after this the interference in the extremely short muscle causes filament interaction and attachment to wrong spots which causes loss of tension

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80
Q

explain a muscle contraction

A

myosin heads attach, ratchet, reattach, pulling sarcomeres together and shortening muscle

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81
Q

what is the functional unit of the muscle

A

sarcomeres

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82
Q

why is the trunk white muscle in a helical pattern?

A

bent muscles can be longer in a compact area. white muscle needs to be long so they can contract less while still generating a lot of force but stay in the peak force zone of sarcomere length curve

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83
Q

what powers slow swimming

A

red muscles - low amplitude contractions

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84
Q

what powers escape responses

A

white muscle - high amplitude

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85
Q

explain the length-tension curve in regards to red and white muscle

A

red muscle is shorter and contracts more often so it may not always be in the peak force zone but white muscle is long enough that even a full contraction leaves it still long enough to remain in the peak force zone

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86
Q

what are the higher performance muscle recruitment patterns

A
  • mostly BCF propulsion done with white fibres
  • sprints, escape, fast starts, burst swims, some fast steady swimming
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87
Q

what are lower performance muscle recruitment patterns

A
  • mostly MPF or combo MPF/BCF propulsion
  • mostly red fibres
  • lowest is MPF undulatory
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88
Q

physical characteristics of red muscle

A
  • slow oxidative fibres (require O2 to make ATP)
  • 60-150um fibre diameter
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89
Q

metabolic properties of red muscle

A
  • aerobic
  • 1.9-2.5 capillaries/fibre
  • 15-35% of fibre volume is mitochondria
  • lipid and glycogen stores
  • usually high myoglobin
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90
Q

electromechanical coupling of red muscle

A
  • phasic
  • multiterminal distributed innervation
  • sarcoplasmic reticulum 0.1-0.6% fibre volume
  • t-tubule system 3-5% fibre volume
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91
Q

physical characteristics of white muscle

A
  • FG (fast glycolytic fibres)
  • fatigues quickly
  • up to about 300um in diametre - larger than red, more force
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92
Q

metabolic properties of white muscle

A
  • anaerobic
  • 0.2-0.9 capillaries/fibre
  • 0.5-4% fibre volume is mitochondria
  • mostly glycogen stores
  • low myoglobin
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93
Q

electromechanical coupling of white muscle

A
  • phasic
  • focal innervation in less derived species
  • polyneural innervation in more derived
  • sarcoplasmic reticulum 0.3-0.9% fibre volume
  • t-tubule system 5-14% fibre volume
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94
Q

what is the t-tubule system?

A

brings electric signal from surface of muscle to sarcomere

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95
Q

major differences between red and white muscle

A
  • red: slower, aerobic, smaller capillaries for easier diffusion, more mitochondria, lipid and glycogen stores, high myoglobin to deliver more O2
  • white: faster, anaerobic, less mitochondria leaves more space for actin and myosin = more force, glycogen stores, higher volume of sarcoplasmic reticulum and t-tubule system for faster contractions
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96
Q

type of innervation used in white muscle of less advanced teleosts (herring)

A
  • focal innervation
  • all or none contraction of white muscle
  • only for bursts/sprints
  • 1 neuron going to each muscle at the end
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97
Q

type of innervation used in white muscle of advanced teleost (carp)

A
  • polyneural distributed innervation
  • graded concentration of white muscle
  • can support red muscle in sustained swimming
  • pink muscle present
  • multiple nerves innervating each muscle
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98
Q

what is phasic in muscles

A

contracting and relaxing on and off

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99
Q

what is tonic in muscles

A

maintaining force constantly

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100
Q

what are Beamish (1979)’s categories of swimming?

A
  • sustained
  • prolonged. subcategory: critical swimming speed
  • burst swimming
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101
Q

sustained swimming:

A
  • swimming speeds that can be maintained for long periods (>200min) without resulting in muscle fatigue
  • ranges from 0.5 - 2 lengths/second
  • slow but can go forever
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102
Q

prolonged swimming:

A

swimming speeds that can be maintained for a shorter duration (>20sec to <200min) and end in fatigue
- 2-5 lengths/second

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103
Q

critical swimming speed:

A
  • Brett (1964)
  • subcategory of prolonged
  • maximum velocity a fish can maintain for a given period
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104
Q

burst swimming:

A
  • high speeds that can only be maintained for brief periods < 20sec
  • initial acceleration phase then a period of steady swimming called the sprint
  • usually predator-prey interaction
  • up to 20 lengths/second
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105
Q

how is burst swimming measured?

A
  • laser beam detection system
  • fish stimulated and swims across chamber
  • s-start: straight fast start
  • c-start: change in direction then speed off
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106
Q

how is prolonged/sustained swimming measured?

A
  • critical swimming speed test
  • speed slowly increased until fish becomes exhausted
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107
Q

how is swimming speed energetics measured?

A
  • swim-tunnel respirometry
  • Brett-type: large, hard to transport
  • blatzka: small, easily transported, harder to access fish
  • fish swims at different speeds and oxygen consumption is measured
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108
Q

how does oxygen change during swimming?

A
  • increases in an exponential fashion with swimming speed until a maximum value
  • drag is proportional to velocity squared
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109
Q

why is cost of transport u-shaped?

A
  • slower swimming takes longer so more O2 is used by basal metabolism
  • faster swimming drag starts to overcome benefit saved by BM
  • optimal speed in middle
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110
Q

what is aerobic scope?

A
  • energy used above that needed to maintain essential life processes
  • aerobic scope = MMR - SMR
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111
Q

why do larval fish use passive drift or short bursts?

A
  • larvae are so small they can’t continuously swim fast enough to energetically overcome viscosity of water
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112
Q

what is reynold’s number?

A
  • ratio of momentum (inertial force) to viscous forces
  • R = (fish length)(velocity)/(kinematic viscosity)
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113
Q

what are the densities of freshwater and seawater?

A

1000kg/m3 and 1026kg/m3

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114
Q

why do most fish naturally sink?

A

the density of most of their tissues is greater than the density of water

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115
Q

how do sharks/sturgeons maintain their position in the water column using their fins?

A
  • large pectoral fins, heterocercal tail, and/or broad head provide dynamic lift
  • must constantly swim so very expensive
  • use pectoral fins to steer
116
Q

how do elasmobranchs maintain their position in the water column using liver?

A
  • many have large livers
  • 90% of liver may be oil
  • large proportion of oil is squalene - density only 856
  • other fish use wax esters in various locations
117
Q

how can tissue changes be used to maintain buoyancy?

A
  • decrease density of tissues
  • watery tissues (decreased protein content)
  • poorly ossified bone
  • some species have a gelatinous layer under their skin (lumpsucker)
118
Q

how do bony fish usually maintain buoyancy?

A
  • use of a gas bladder
  • needs to occupy ~7% and 5% of body volume in fresh water and salt water for fish to be neutrally bouyant
119
Q

what are the types of swim bladders?

A
  • physostomous
  • physoclistous
120
Q

what is a physostomous swim bladder?

A
  • has a connection (pneumatic duct) between the oesophagus or anus and the swim bladder
  • innervated sphincter muscles guard entrance to duct and are relaxed to expel gas as muscles in bladder and body wall contract
  • fish gulps air to fill - have to go to surface
  • crude but fast
  • ecologically constrictive
121
Q

what is a physoclistous swim bladder?

A
  • no connection between gas bladder and digestive tract
  • changes in volume can only be achieved by secreting gases in and out
  • 2/3 of all teleosts
  • in some fish resorption and secretion take place in different chambers, in others there’s only one chamber
122
Q

what is the oval?

A
  • patch of densely packed capillaries on dorsal wall of swimbladder or posterior lining of swimbladder
  • vessels dilate when gas resorbed
  • passive process
  • functional area controlled by diaphragm or sphincter
  • movement across rest of bladder wall prevented by 4 tissue layers and layer of guanine crystals
123
Q

what is the gas gland?

A
  • organ/tissue made of specialized epithelial cells that can produce protons and lactate through glycolysis and CO2 by dehydration of bicarbonate and the TCA cycle and pentose phosphate shunt
  • shallow fish have gas composition close to atmosphere
  • deep sea fish contain higher proportions of O2
124
Q

how does the gas gland fill the bladder?

A
  • lactate leads to salting out of gases in blood
  • CO2 and H+ that enter blood release O2 from Hb through root and bohr shifts
  • provides partial pressure gradient for diffusion of gases into swimbladder
  • under parasympathetic (cholinergic) control - gas secretion goes up when stimulated
125
Q

what is the rete mirable?

A
  • consists of thousands of small vessels
  • vessels running to the gas gland (afferant) and those returning (efferent)
  • flow under alpha-adrenergic control
126
Q

how does the rete mirable work?

A
  • vessels only separated by 1um
  • very efficient countercurrent exchange system
  • transfer of blood gases, lactate, HCO3-, and H+ from efferent to afferent blood
  • amplifies secretion in gas gland and is required to secrete gas at depth
  • deeper the fish longer the rete
127
Q

advantages of physostomus

A
  • volume of bladder (therefore buoyancy) can be changed rapidly
128
Q

disadvantages of physostomus

A
  • fish has to return to surface to increase volume if rete/gland are poorly developed
  • bladder gases become compressed if fish wants to go deep
  • cannot submerge if inflation too much for particular depth
129
Q

advantages of physoclistous

A
  • fine control
  • can live at depth
130
Q

disadvantages of physoclistous

A
  • changes in volume slow
  • energetically expensive
131
Q

what is described as the ecological master factor by brett 1971

A

temperature

132
Q

what ranges can aquatic habitat temperatures be

A

-1.5C - 45C

133
Q

what categories can fish be classified into based on how they regulate body temperature?

A
  • ectotherm
  • regional heterotherm
134
Q

what are the two categories of ectotherms?

A
  • stenothermal
  • eurythermal
135
Q

what is an ectotherm?

A
  • do not produce enough heat through metabolism to elevate their body temperature
  • body temperature dependent on heat lost or gained from the environment
  • most fish
136
Q

why do most fish have a body temperature close to their environment?

A
  • extreme heat loss at skin and gills
137
Q

what is stenothermal?

A

organisms that can only tolerate a narrow range of temperatures

138
Q

what is eurythermal?

A

organisms that can tolerate a wide range of environmental temperatures

139
Q

what are regional heterotherms?

A
  • fish that maintain regions of their body above ambient temperature
  • tunas, sharks, billfishes
140
Q

why do tunas and some sharks use regional heterothermy?

A
  • need warm muscles to support high levels of activity - high routine swimming speeds
  • arterial blood generally cold due to large surface area of gills
  • cool temperatures reduce force production and efficiency of muscle contraction
141
Q

how do tunas and sharks use regional heterothermy on their muscles?

A
  • cold blood leaving gills doesn’t go down the core of the fish via dorsal aorta - goes to large peripheral vessels (cutaneous arteries)
  • red muscle moved centrally to reduce heat loss
  • muscles warmed using counter-current heat exchanger (rete mirable) - warm venuous blood leaving muscles transfers heat to cool arterial blood entering from cutaneous artery
  • heat exchange 90-95% efficient
  • muscle temperature as much as 10-20C above water temperature
142
Q

why do billfishes use regional heterothermy?

A
  • dive to depths of 600m or more for prey during the day and face temperature decreases of up to 20C
  • feed on squid and other prey at these depths so they need to maintain visual acuity and brain/nervous function
143
Q

how do billfish warm their eyes?

A
  • pair of eye muscles (superior rectus muscles) are modified for heat production - called brain heater organs
  • no longer have contractile function but are packed with mitochondria and SR
  • stimulation of these muscles causes release of Ca2+ into myoplasm, and SR Ca2+ - ATPase pumps on the SR pump it back in - ‘futile cycle’
  • futile cycle consumes a lot of ATP to release and absorb Ca2+ and heat is generated by inefficiency
144
Q

what are the steps billfish muscles use to generate futile cycle

A
  1. Ca2+ released into the myoplasm
  2. SR Ca2+-ATPase pumps pump Ca2+ back in to SR
  3. uses a lot of ATP so mitochondria make too much which gets released as heat
145
Q

how do most fish control their body temperature?

A

behavioural thermoregulation

146
Q

why do fish select certain temperatures?

A
  • conserve energy
  • increase rate of digestion
  • optimize physiological processes
147
Q

what causes fish to initiate thermoregulatory behaviour?

A

response to sensory input from both peripheral and central thermoceptors

148
Q

where are the thermoceptors in fish?

A
  • hypothalamus
  • important for adjustments in ventilation
  • anticipate changes in oxygen supply and demand as a result of temperature changes
149
Q

how do fish respond to changes in the hypothalamus?

A
  • when hypothalamus is cooled they become thermophilic (heat seeking)
  • when hypothalamus is warmed they become thermophobic (heat avoiding)
150
Q

what factors modify fish’s temperature setpoint?

A
  • preferred temperature can vary with time of day
  • acclimation temperature (physiological processes optimized for acclimated temperature)
  • selected temperature decreases with age in striped bass and rainbow trout
  • hypoxia-induced hypothermia
151
Q

what is hypoxia-induced hypothermia?

A
  • resetting of thermostatic setpoint
  • allows fish to avoid oxygen limiting conditions
  • if environment is hypoxic move to colder water
152
Q

why do fish move to cold water when hypoxic?

A
  • colder water holds more dissolved O2
  • higher Hb affinity for O2
  • slower metabolic processes conserve O2
153
Q

what happens when a fish is exposed to prolonged cold or warm?

A
  • elicits compensatory changes in physiology which permit the animal to adapt to its new thermal environment
154
Q

what is acclimatization?

A
  • changes in physiological processes in natural environment as exposed to seasonal changes in photoperiod, temperature, etc
  • ex. fish acclimated to cold temperatures can maintain higher metabolic rates at low water temp than fish acclimated to warm temp like 25C
155
Q

how do fish physiologically cope with temperature change?

A
  • alteration in enzyme activity/protein structure: 2 mechanisms
  • alterations in the fluidity (viscosity) of biological membranes: homeoviscous adaptation - stabilization of membrane function
156
Q

what are the 2 mechanisms used to alter enzyme activity/protein structure?

A
  1. change in the molecular structure of the protein/enzyme = production of different isoforms/isozymes
  2. change in the concentration of proteins/enzymes, production of new proteins
157
Q

how do fish alter fluidity of biological membranes?

A
  1. changing the degree to which membrane lipids are saturated - more unsaturated lipids = greater fluidity
  2. alter the concentration of cholesterol in the membrane - increased cholesterol = decreased fluidity
158
Q

two strategies for dealing with the cold

A
  1. metabolic depression
  2. freezing point depression: glycerol and antifreeze proteins
159
Q

what is metabolic depression?

A
  • some fish respond to seasonal extremes in temperature by entering a state of dormancy
  • often called torpor
  • associated with a decrease in cellular metabolism
  • considerable energetic savings and benefits outweigh those of acclimatization
160
Q

examples of fish that use metabolic depression

A
  • at temperatures below 8C american eel ceases feeding and burrows into the mud
  • in winter the cunner finds a rock crevice, produced a mucous cocoon, and becomes unresponsive
161
Q

why is freezing point depression used?

A
  • seawater doesn’t freeze until -1.9C but serum freezes at -0.7C
  • fish need to survive in waters permanently or seasonally below -0.7C
162
Q

how do fish do freezing point depression?

A
  • increase concentration of solutes in blood:
    1. glycerol production: compound accumulates to high levels in species such as rainbow smelt (up to 600mmol)
    2. produce anti-freeze proteins: prevent ice crystal formation and can be as high as 10mg/ml (account for as much as 3% of total plasma protein) - several types
163
Q

steps of gas exchange model

A
  1. convection - water moved over gills
  2. diffusion - O2 diffused across epithelium
  3. convection - O2 carried to tissues by blood
  4. diffusion - O2 leaves Hb and diffuses into tissues
164
Q

what are the two types of fish ventilation?

A
  1. buccal pumping
  2. ram ventilation
165
Q

what is buccal pumping?

A
  • associated with synchronous expansion and contraction of the buccal and opercular cavities
  • expanding buccal cavity creates suction
  • ~10-15% of total metabolism
  • can vary frequency and amount of water
166
Q

what factors affect volume of water pumped over gills?

A
  • fish size
  • temperature
  • water O2 content
  • activity
  • respiratory volume usually ranges from 100-300ml/min/kg at rest but can increase 15-20 times
167
Q

how does respiration frequency and volume change with temperature increase

A
  • metabolism goes up
  • O2 in water goes down
  • more O2 needs to be moved more quickly across gills
168
Q

what is ram ventilation?

A
  • used when swimming
  • fish keeps mouth open and lets water flow over gills
  • doesn’t take much energy
169
Q

physical characteristics of fish gills

A
  • teleosts have 4 pairs of gill arches in opercular cavity
  • each gill composed of gill filaments (primary lamellae, 2 rows per arch) and secondary lamellae (2 rows per filament)
  • gas exchange occurs at filaments
  • for most fish gill surface area ranges from 2-4cm2/g mass but tunas can be as high as 14cm2/g mass
170
Q

how does gas exchange occur over the gills?

A
  • water flows through slit-like channels between neighbouring lamaellae
  • gas exchange occurs between water and surface of secondary lamellae
  • blood flow and water flow are countercurrent
  • near constant gradient between water and gas partial pressures is maintained due to countercurrent - results in ~1.6x O2
171
Q

why are gills efficient at gas exchange?

A
  • high surface area
  • thin membrane
  • countercurrent flow of blood and water
172
Q

what specially modified gill structures do walking catfish have that allows them to breathe air?

A
  • respiratory fan
  • arborescent organ
173
Q

what is the arborescent organ

A
  • gill structure used by walking catfish to breathe air
  • rigid and maintain their surface area out of water unlike gills which collapse
174
Q

types of extrabranchial oxygen uptake

A
  • cutaneous respiration
  • mouth
  • gut
  • swimbladders
  • lungs
175
Q

what is cutaneous respiration

A
  • most fish capable of absorbing oxygen through highly vascularized skin
  • diffusion an important role in larval fish
  • skin can comprise up to 96% of respiratory surface
  • in adult fish ranges from 5-30% but in most species only enough to meet metabolic demands of the skin
  • more important in amphibious species
176
Q

what is mouth respiration

A
  • ex. electric eels have a vascularized area in their buccal cavity and gulp air
177
Q

what is gut respiration

A
  • several groups of tropical fish have specialized gut parts for oxygen uptake from swallowed air
  • CO2 eliminated at another site
178
Q

what are swimbladders

A
  • fish gulp air into modified swim-bladder for gas exchange
  • connection between swimbladder and oesophagus required (physostomous)
  • gars, bowfin, bichir
179
Q

what are lungs

A
  • 2 separate circulatory systems like mammals
  • only present in lungfish
  • obligate airbreathers
180
Q

what types of cells are blood made of

A
  • leukocytes
  • red blood cells
181
Q

what are leukocytes

A
  • white blood cells
  • usually less than 1% of blood cells
  • function in clotting and immune response
182
Q

what are red blood cells

A
  • erythrocytes
  • funciton in O2/CO2 transport
  • in most fish haematocrit 20-30% but in active ex. tuna 50%
183
Q

what is haemoglobin

A
  • carried in red blood cells
  • made of 4 protein subunits (globins)
  • each subunit has a prosthetic (heme) group with an iron Fe2+ molecule at its centre
  • each haemoglobin molecule can combine with 4 oxygen molecules
  • 1 O2 per heme
184
Q

what is the haemoglobin - oxygen dissociation curve?

A
  • the relationship between % saturation and oxygen partial pressure
  • sigmoidal shape due to cooperative binding characteristics
185
Q

what determines extent to which O2 is bound to haemoglobin?

A

the partial pressure of oxygen in the blood

186
Q

what is cooperative binding?

A

oxygen binding to the first heme group increases the ability of the other heme groups to bind O2

187
Q

why is binding of O2 reversible

A
  • allows it to perform its role as an oxygen carrier
  • load at respiratory surface then unload at tissues
188
Q

what happens to O2 bound to haemoglobin when PO2 changes?

A
  • as PO2 increases more O2 binds
  • as PO2 decreases O2 is lost
189
Q

how is the affinity of a respiratory pigment expressed?

A
  • P50 value: the PO2 at which 50% of the respiratory pigment is saturated with oxygen
  • lower P50 value = higher affinity
190
Q

what causes a decrease in Hb binding affinity

A
  • increase in temperature
  • increase in PCO2
  • decrease in pH
  • increase in RBC organic phosphates (ATP, GTP, DPG)
191
Q

what is a bohr shift?

A
  • right shift of the dissociation curve
  • decreased affinity with decrease in pH
192
Q

what is a root shift?

A
  • downward shift of dissociation curve
  • decrease in Hb O2 carrying capacity with increased CO2 or decreased pH
  • only happens in fish
193
Q

when would a fish want affinity to decrease?

A

P50 increase =
- O2 comes off Hb easier
- working muscles receive more O2 quickly
- O2 can come off to be secreted into swim bladder

194
Q

when would a fish want affinity to increase?

A

P50 decrease =
- living in a hypoxic environment
- not very active

195
Q

how can fish adjust Hb for suboptimal environments/conditions

A
  • have Hb with increased affinity
  • have more than one isoform of Hb each with a different affinity ex. trout, cod
196
Q

process of gas movement between tissues and blood

A
  • CO2 leaving tissue enters plasma and rbc
  • CO2 dissociates mostly into HCO3- with some attaching to Hb creating carbamino Hb
  • carbamino formation releases O2 from Hb so O2 can enter plasma then tissues
  • HCO3- in rbc builds up then a chloride shift through an antiport puts it into the plasma
  • HCO3- buildup in rbc causes pH to decrease, causing a right shift of the curve, allowing easier offload of O2 into tissue
197
Q

what forms are CO2 in in the blood on the way back to the gills

A
  • 5% gas
  • 10-15% carbamino
  • 80-85% HCO3-
198
Q

process of gases moving from blood through gills to water

A
  • HCO3- chloride shifts back into rbc
  • loss of CO2 and buildup of HCO3- drives reaction to produce more CO2
  • CO2 diffuses out of rbc and plasma through gills because of gradient between water and blood
  • curve shifts back to the left when CO2 leaves increasing affinity for O2
199
Q

what is a chloride shift

A
  • prevents bicarbonate from building up in rbc
  • allows reaction to continue
200
Q

what is the haldane effect

A
  • deoxygenation of Hb at the tissues reduces the change in PCO2 and pH as CO2 enters blood
201
Q

what is band III protein

A
  • the anion carrier which exchanges Cl- and HCO3-
  • passive process depending on gradient of ions
202
Q

what are the 4 chambers of the fish heart?

A
  • sinus venosus
  • atrium
  • ventricle
  • bulbus/conus arteriosus
203
Q

what is the sinus venosus

A
  • thin walled sac that collects venuous blood from circulation
  • location of pacemaker cells
  • low pressure
  • prepares blood to enter atrium
  • first at ventral end
204
Q

what is the atrium?

A
  • provides the first increase in blood pressure
  • partially fills ventricle
205
Q

what is the ventricle?

A
  • thick walled muscular chamber
  • provides main propulsive force for circulatory flow
  • contracts
206
Q

what is the bulbus/conus arteriosus

A
  • elastic chamber that dampens extremes in pressure and results in continuous flow of blood to the gills
  • lowers pressure before blood gets to gills so they don’t blow up
  • a lot of tissue and elastin
  • distensible
207
Q

difference between conus arteriosus and bulbus

A
  • conus: has muscle and valves
  • bulbus: no valves just collagen
208
Q

different shapes of ventricle and purpose

A
  • pyrimidal: high pressure, trout/tuna
  • sac-like: low pressure, flounder
  • tubular: medium pressure, cod
209
Q

how fish hearts are split into types

A

based on presence/absence of a coronary circulation and compact myocardium in the atrium and ventricle

210
Q

characteristics of compact myocardium

A
  • on the outside
  • high PO2
  • high O2
211
Q

characteristics of spongy myocardium

A
  • on the inside
  • low PO2
  • low O2
212
Q

type I of fish heart

A
  • 70% of fish
  • no compact myocardium
  • some spongy myocardium
213
Q

type II of fish heart

A
  • some compact
  • coronary vessels in compact - provide O2 to heart tissue
  • ex. trout
214
Q

type III of fish heart

A
  • thicker compact
  • coronary vessels become present in sponge
  • ex. mackeral
215
Q

type IV of fish heart

A
  • very thick compact
  • major vessels in compact
  • coronary vessels and atria in both
  • thicker = more pressure allowed
  • high performance
  • ex. tuna
216
Q

what is the pericardium

A
  • connective tissue membrane surrounding the heart
  • adhered to heart and bone and structures that form cavities
  • can be compliant or non-compliant
217
Q

purposes of pericardium

A
  • barrier to infection
  • prevents heart chambers from over-expansion
  • enhanced atrial filling and ultimately stroke volume (only for non-compliant)
218
Q

compliant pericardium

A
  • not fully closed
  • only allows heart to fill at positive pressures
  • no vis-a-fronte filling only vis-a-tergo
219
Q

noncompliant pericardium

A
  • intact
  • allows vis-a-fronte filling
  • enhances artial filling and ultimately stroke volume
  • when ventricle contracts negative pressure happens in pericardial cavity causing the atrium to expand and increase venuous return
220
Q

diastole

A

portion of the cardiac cycle that the ventricle is relaxing

221
Q

systole

A

portion of the cardiac cycle that the ventricle is contracting

222
Q

what is P in an ECG

A

atrial contraction/depolarization

223
Q

what is QRS in an ECG

A

ventricular contraction/repolarization

224
Q

what is T in an ECG

A

ventricular relaxation

225
Q

when does diastole take place

A

between T and R

226
Q

when does systole take place

A

between R and T

227
Q

relative length of systole and diastole

A

diastole = 2/3 of the cycle

228
Q

steps of changes in chamber and blood pressure during a cardiac cycle

A
  • atrial contraction
  • atrium starts to fill
  • atrial ventricular valve closes
  • atrium relaxes
  • ventricle pressure rapidly increases
  • ventricle valve opens when ventricle pressure is equal to venous pressure
  • ventricle and venous pressure increase and bulbus expanding
  • after contraction valve closes and blood flows out into circulation
229
Q

changes in ventricle volume during cardiac cycle (pressure-volume loop)

A
  • volume increases = stroke volume
  • increase in pressure with same volume
  • increase in pressure with decrease in volume until 0
  • relaxation = pressure goes all the way down
230
Q

what is cardiac output

A
  • product of heart rate and stroke volume (volume pumped per beat)
  • both important for mediating changes in cardiac output
231
Q

heart rate is determined by

A
  • intrinsic rhythm of the pacemaker cells
  • cholinergic inhibitory nervous tone: release of acetylcholine onto pacemaker cells
  • adrenergic nervous tone and circulating catecholamines - increase in HR
232
Q

why does stroke volume decrease as heart rate increases

A
  • diastole period decreases
  • less time to fill
  • edv goes down
  • stroke volume decrease
233
Q

what is stroke volume determined by

A
  • heart rate - time available for filling, SV may be limited at very high HR
  • filling (venous) pressure and frank-starling mechanism (end-diastolic volume)
  • output pressure - can affect end-systolic volume - normally close to 0
234
Q

how does pressure affect stroke volume

A

as pressure increases stroke volume increases until hitting limit

235
Q

stroke volume equation

A

stroke volume = end dyastolic volume - end systolic volume

236
Q

blood pressure equation

A

pressure = flow x resistance

237
Q

blood flow of a water breathing teleost

A
  • high pressure low O2 blood from the heart pumped through the gills
  • high O2 blood leaves gills and goes through dorsal aorta
  • some blood goes to secondary circulation through the arterio-arterial anastomosis
  • some blood goes to primary circulation to go to tissues
  • pressure increases and O2 decreases as blood moves back toward heart
238
Q

difference between artery and vein

A

artery delivers blood and vein drains it

239
Q

what are portal systems

A

veins that take blood from 1 capillary bed to another without going through the heart

240
Q

what are the 2 portal systems in fish

A
  • renal
  • hepatic
241
Q

purpose of the renal portal system

A

delivers blood to posterior tissues first then goes through kidney so it can filter buildup from the muscles

242
Q

purpose of the hepatic portal system

A

delivers blood first to digestive organs then to liver where carbs and fats from digestion are stored and processed

243
Q

why do some fish have accessory hearts

A

if a fish is really long there won’t be enough pressure through to the posterior to get blood back to the main heart quickly. accessory hearts help pump it along

244
Q

blood flow of a lungfish

A
  • separate blood flows from lung and tissues
  • O2 rich blood from lung goes through thick gill arches where O2 won’t diffuse out into hypoxic water
  • deoxygenated blood from heart goes through gills
  • if breathing air pulmonary vasomotor segment contracts closing the ductus so more blood is directed to the pulmonary artery toward the lung
  • when in water pulmonary vasomotor segment relaxes so more blood goes through ductus to dorsal aorta towards tissues
245
Q

two tests for determining minimum and maximum temperatures causing mortality

A
  1. critical thermal maxima (minima) test: CTmax and CTmin tests
  2. upper and lower incipient lethal temperatures (UILT and LILT)
246
Q

what is the critical thermal maxima (minima) test

A
  • protocol where temperature is acutely increased from the acclimation temperature at a steady rate
  • temperature at which the fish loses equilibrium is recorded because nervous system is first to be disrupted
247
Q

what is the upper and lower incipient lethal temperature test

A
  • temperature at which 50% of fish acclimated to a certain temperature die after being rapidly transferred to a new temperature for a defined period
  • usually 96 hours
  • most common test used to assess thermal tolerance and define thermal niche
248
Q

why might thermal tests not be ecologically relevant

A
  • do not allow fish to behaviourally thermoregulate
  • thermal tolerance is related to the time spent at an acclimation temperature
  • thermal tolerance is related to time of exposure
  • fish are often exposed to fluctuating thermal environments irl
249
Q

what happens to a fish tolerance after acclimation

A
  • tolerance limit will shift in the direction it acclimated to
  • ex. from 10-25C fish will be able to stand higher temperatures but be damaged by lower
250
Q

what is the zone of resistance

A
  • the period where an animal can tolerate high temperatures if the change is quick
  • shorter the exposure time the higher temperature it can stand
251
Q

why does oxygen demand increase with temperature?

A
  • elevated temperature increase the kinetic energy of molecules and alter the interaction between substrates and enzyme catalysts pushing them over their activation energy = faster rates of reaction = increased metabolism
  • if an organism can’t maintain/control their body temperature small changes in temperature can have a major influence on metabolic rate
252
Q

what is Q10

A
  • Q10 = MR2/MR1^10/(t2-t1)
  • change in metabolic rate after drop or increase in temperature
  • normally ranges from 2-3
  • Q10 of a particular parameter depends on range of temperatures being considered
253
Q

what is OCLTT

A
  • oxygen and capacity limited thermal tolerance
  • originally developed by H.O. Portner
  • generally applies to aquatic organisms but not universal
  • relates thermal tolerance to physiology, and its consequences for aquatic organisms at the animal and ecosystem level
254
Q

what is Tp in OCLTT

A
  • pejus (getting worse) temperature
  • limit for growth and reproduction
255
Q

what is Tc in OCLTT

A
  • critical temperature
  • limit for activity
256
Q

what is Td in OCLTT

A
  • temperature limit for survival
257
Q

why are temperature-induced increased in oxygen demand a problem

A

limitation in aerobic scope

258
Q

what happens to cardiac function as temperature increases

A
  • increased heart rate
  • lowered stroke volume due to shorter filling time
  • HR starts to get arrythmic and pump less blood
  • the temp is going up so the fish needs more O2 but the heart can’t keep up
259
Q

what limits cardiac output?

A
  • maximum heart rate
  • appearance of arrhthymias
260
Q

can the OCLTT explain inter-specific differences in upper thermal tolerance?

A
  • sometimes but doesn’t always fit
  • many other factors to consider ex. mito function
  • some fish with lesser metabolic scope have a smaller thermal tolerance
261
Q
A
261
Q

explain multiple performances - multiple optima

A
  • thermal tolerance depends on priority limiting factor
  • each physiological process has an optimal temperature
262
Q

how does temperature affect mitochondrial function?

A
  • NADH + H+ and FADH2 from krebs cycle drop off H+ and electrons to I and II of the ETC
  • H+ crosses into membrane from matrix creating a buildup which makes an electrochemical gradient
  • when H+ moves down its electrochemical gradient through ATP synthase it creates energy to make ATP from ADP + Pi
  • as temperature rises more H+ leaks back into matrix and O2 is consumed by uncoupled rxns
263
Q

what is state 3 of mitochondrial function?

A

normal consumption of O2 when mito is provided with NADH and FADH2

264
Q

what is state 4 of mitochondrial function?

A
  • O2 consumed after no krebs cycle product are left
  • shows how much O2 is consumed by proton leak
265
Q

what is the RCR

A
  • respiratory coupling ratio
  • RCR = state 3/state 4
  • mitochondrial efficiency
  • lower = worse
266
Q

what is an ROS

A
  • reactive oxygen species
  • highly reactive chemical species due to the presence of unpaired electrons in the outermost valence shell
  • ex. superoxide, hydrogen peroxide, hydroxyl radical
267
Q

what causes ROS to be produced

A
  • normal consequence of mitochondrial respiration
  • electrons leak from complexes I and III mostly
  • usually able to be broken down by enzymes
  • can be produced in excessive amounts under certain conditions ex. high temp
  • if too many can cause cell damage, contribute to proton leak, and damage proteins
268
Q

what is SOD

A
  • superoxide dismutase
  • breaks superoxide down into hydrogen peroxide (H2O2)
269
Q

what is GPx

A
  • glutathione peroxidase
  • breaks hydrogen peroxide down into water
270
Q

what is NO

A
  • nitric oxide
  • reactive oxygen species
  • when combined with hydrogen peroxide causes protein nitration (damage)
271
Q

why are high temps bad for making ROS

A
  • movement in the ETC is fast so superoxide production overwhelms the system
  • can’t break down ROS fast enough
  • ROS cause damage and eventually animal succumbs
272
Q

what do ROS damage

A
  • proteins
  • membranes
  • DNA
273
Q

what is superoxide broken down into by enzymes

A
  • H2O (good)
  • H2O + O2 (good)
  • H2O2 (damage)
  • OH- (damage)
  • superoxide itself causes damage
274
Q

what is hypoxia

A
  • shortage of O2
  • water PO2 when physiological function is first compromised
275
Q

what is anoxia

A
  • complete absence of oxygen
  • some fish have special adaptations to survive
276
Q

where does most hypoxia occur globally

A
  • near major cities
  • caused by runoff, human waste
  • algal blooms = eutrophication = respiration = O2 used up = bacteria using O2 when algae dies
277
Q

why is there no longer a cod fishery in areas of the gulf of st lawrence

A
  • areas became hypoxic at depth
  • cod are demersal (live close to bottom)
  • cod could no longer live in hypoxic areas
278
Q

how do most fish deal with hypoxia

A
  • most are oxygen regulators
  • can maintain oxygen consumption down to a specific PO2 before oxygen consumption fails
279
Q

what is the critical oxygen partial pressure (Pcrit)

A
  • PO2 where fish can no longer maintain normal oxygen consumption
  • at a fish’s Pcrit O2 consumption goes from being independent of environmental O2 levels to dependent on water O2
  • species-specific and dependent on temperature and metabolic activity
280
Q

what is required to survive hypoxia below the Pcrit

A

rapid reorganization of cellular metabolism to suppress ATP consumption to match the limited capacity for O2-dependent and O2-independent ATP production

281
Q

what is hypoxemia

A

the point where fish can’t saturate Hb to a good extent

282
Q

water PO2 vs O2 consumption curve

A
  • at normoxic maximal, routine, basal, locomotion, reproduction, and growth O2 consumption can be supported
  • after water becomes hypoxic metabolic activities slowly decline and use less O2 until hitting Pcrit
  • after Pcrit all activities go down rapidly and fish dies
283
Q

behavioural strategies to survive hypoxia

A
  • aerial respiration: spend more time at surface gulping air
  • swimming activity: decrease activity so less O2 is consumed
284
Q

physiological/biochemical mechanisms to survive hypoxia

A
  • hypoxic bradycardia
  • ethanol production
  • increase ventilation
  • increase in gill surface area
  • increase in hemoglobin levels
  • alter Hb isoforms
  • decrease basal MO2
  • decrease cellular energy consumption
285
Q

how does hypoxic bradycardia help?

A
  • slows the heart rate
  • slower heart rate = more time for heart to fill with blood (diastole time increase)
  • more time and volume of blood for O2 to diffuse
286
Q

how does ethanol production help survive hypoxia?

A
  • turns pyruvate into ethanol instead of lactate
  • lactate presence decreases pH which lowers Hb affinity to O2
  • ethanol can easily diffuse through cells and be excreted

fish (2 decks)

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