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Reading Assignment:
Chapter 5: Buoyancy and Thermal
Regulationbigeye jackend
Hemoglobin--molecule of O2 transport
• Structure– protein– monomer in Myxini & Cephalasipdomorphi– tetramer in Gnathostomata (4 polypeptide chains)
chain similar in coelacanth and tadpole
end
Hemoglobin (Hg) cont.• Occurrence: erythrocytes (RBCs)
– up to 4M RBC/mm3 of blood
• RBC’s nucleated in fish• Hg Absent in some species (Channichthyidae)
Antarctic ice fish
endfish human
• Some species have more than one type of hemoglobin
• Catostomus clarki -- desert sucker has an additional form of pH insensitive Hg
end
end
Factors affecting blood oxygen affinity
• pH
• pCO2 (partial pressure of carbon dioxide)
end
0 80 1600
100
50
pO2 mm Mercury
% S
atur
atio
n of
Hg
pH 8.02
pH 7.47
Air saturation
1.affinity
2. capacity
Bohr
Root
Effect of pH on Hg--two components
end
data for winter flounder
• Bohr effect--decrease in affinity of hemoglobin for O2 due to decreasing pH or increasing PCO2
affinity: strength of attraction of Hg for O2
• Root effect--decrease in capacity of Hg for O2 due to decreasing pH or increasing PCO2
(extreme Bohr effect)
capacity: total quantity O2 of that Hg can carry
end
• more active species tend to have greater Bohr & Root effects
• red versus white muscle
• myoglobin
endperciform skipjack tuna lamnid shark
Advantage of Bohr Effect
TissuesGills
blood circulation
pH lowerpH higher
pCO2 higherpCO2 lowerlactic acidno lactic acid
end
pH?
pCO2?
lactic acid?
Teleost Heart:
sinus venosusatrium
ventricle
bulbus arteriosus
end
Teleost Heart:
sinus venosusatrium
ventricle
bulbus arteriosus
endrelax
Teleost Heart:
sinus venosusatrium
ventricle
bulbus arteriosus
endcontract
Conus arteriosus--Myxini, Ceph., elasmobranchs, gar
heartto gills
end
time
Pre
ssur
e (m
m m
erc.
)
0
60
ventricle
bulbus arteriosus
end
end
Buoyancy strategies
1. Low density compounds
2. Lift generated by swimming
3. Reduction of heavy tissues
4. Swim bladder (air bladder)
end
1. Low density compounds:
Advantages/disadvantages
Substance Specific GravityBone 2.0Muscle 1.05Cartilage 1.1Freshwater 1.002 @20CSaltwater 1.072 @20CLipids 0.9-0.92Squalene 0.86
end
2. Lift generated by swimming:
lift
lift
thrust
sharks Advantages/disadvantagesend
hammerhead shark
end
nurse shark
end
sandbar shark
end
3. Reduction of heavy tissues
Eurypharynx pelecanoides
deepwater fishes
Advantages/disadvantagesend
umbrella mouth gulper
end
umbrella mouth gulper
end
4. Swim bladder
• low density
• adjustable
• most osteichthians
• lost secondarily in some species
end
Two types of swim bladders:
• Physostomous– pneumatic duct– soft-rayed teleosts--herrings, salmonids,
catfishes, cyprinids, eels, etc.
• Physoclistous– blood/circulatory system– spiney-rayed teleosts--Acanthopterygii,
sunfishes, perch, most marine fishes
end
Effects of depth on swim bladder volume
• pressure increases 1 ATM/10m
• swim bladder must be adjustable
• Physostomous fishes adjust volume by gulping or spitting air.– mostly shallow water species– gas-spitting reflex– gulp air at surface
end
Physoclistous inflation/deflation
• circulatory system--source of gases
• rete mirabile (wonderful net) --inflation
• oval window--deflation
• Problem: fish need greater pressure in swim bladder than is achieved by equilibrium with blood gases
end
Oxygen equilibrium—swim bladder inflation
water
hemoglobin
plasma swim bladder
gills swim bladder
O2 O2
O2
end
Counter-current multiplication system
afferent blood
efferent blood
O2hemepO2
O2heme pO2
pO2
swim
bla
dder
O2heme pO2
lactic acid
1
Diagram of basic functional unit(inflation)
end
Function of Rete Mirabile
1. Hemoglobin saturated with O2 (O2 heme)
plasma O2 low (p O2)
end
Counter-current multiplication system
afferent blood
efferent blood
O2hemepO2
O2heme pO2
pO2
swim
bla
dder
O2heme pO2
1 2
lactic acid
end
Function of Rete Mirabile
2. Lactic Acid Secretions heme dumps O2 to plasma pO2 diffuses into swim bladder to equil.
end
Counter-current multiplication system
afferent blood
efferent blood
O2hemepO2
O2heme pO2
pO2
swim
bla
dder
O2heme pO2
lactic acid
1 2
3
end
Function of Rete Mirabile
3. Multiplying effect: pO2 diffuses from efferent capillary to afferent cap. Longer capillaries yield more efficient exchange of oxygen, higher pressures
end
Physoclistous swim bladder
• Pressures up to 300 ATM in some deep sea fishes
• Gases mostly O2, some CO2 and N2
• Guanine crystals in SB wall reduce permeability• Deflation occurs at oval window
– dense bed of capillaries on SB wall
– gasses diffuse into blood
– mucus layer covers window during inflation
end
Summary:• Diffusion of O2; controlled by structure & function
• Relationship O2 bound to hemoglobin versus O2 in plasma
• Effect of pH on affinity/capacity of hemoglobin for O2
• Counter-current multiplier– length of capillaries
– counter-current flow of blood
end
• End
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Grand Forks
Inkster
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Manvel
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y 18
Hwy 1 to Johnstown
I29
Hw
y 18
UND Biol. Area
0.5
mi
3 mi
tree line
Turn right on gravel road
just past tree line, go north
for 0.5 mi, turn right on
two-track road just before
Farm house, pass ravine
on left and turn left following
Ravine on the left, stop by chain
link fence compound.
stop here
farm house
I29
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