• 100 point exam
• covers lectures, assigned readings
• 8-12 short answer questions; 4-6 pts ea
– complete, concise answer
– ex: definition; short description
• 3-5 longer questions; 10-15 pts ea
• Finish by 2:55--budget time
• Power Point lectures on blackboard
• Chapters: 1, 2, 12, 13, 3, 14, 4, 15, 5 end

• low density
• adjustable
• most bony fishes
• lost secondarily in some species end

• 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

• 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
DO water gills
O
2 hemoglobin
O
2 plasma
O
2
How are high pressures achieved?
gaseous O
2 blood rete swim bladder end

Counter-current multiplication system
Diagram of basic functional unit of rete
(inflation) lactic acid
Bohr & Root afferent blood
1
O
2 heme
 pO
2

O
2 heme
  p O
2 pO
2

O
2 heme
  pO
2
 efferent blood end

1. Hemoglobin saturated with O
2
( O
2 heme ) plasma O
2 low ( p O
2
) end

Counter-current multiplication system lactic acid afferent blood
1
O
2 heme
 pO
2

O
2 heme
  pO
2

O
2 heme
  pO
2
2 pO
2
 efferent blood end

2. Lactic Acid Secretions heme dumps O
2 pO
2 to plasma diffuses into swim bladder to equil.
end

Counter-current multiplication system lactic acid afferent blood
1
O
2 heme
 pO
2

O
2 heme
  pO
2

O
2 heme
  pO
2
2 pO
2

3 efferent blood end

3. Multiplying effect: pO
2 capillary to afferent cap. diffuses from efferent
Longer capillaries yield more efficient exchange of oxygen, higher pressures end

Summary of what happens to O
2
1.
Steady supply of oxygen in
2.
Little or none leaves
3.
PO
2 accum. in plasma
4.
Diffusion into SB end

• Pressures up to 300 ATM in some deep sea fishes
• Gases mostly O
2
, some CO
2 and N
2
• 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

• Diffusion of O
2
; controlled by structure & function
• Relationship O
2 versus O
2 bound to hemoglobin in plasma
• Effect of pH on affinity/capacity of hemoglobin for O
2
(Bohr & Root)
• Counter-current multiplier
– length of capillaries
– counter-current flow of blood end

end

• Cold-blooded -poor descriptor
• Poikilotherm (n); poikilothermic (adj)
– variable body temperature
– opposite = homeotherm
• Ectotherm (n); ectothermic (adj)
– temp. determined by environment
– opposite = endotherm end

Heat generated by metabolism skin gills body skin end

• nearly all fishes
• choose from available temperatures
• concept of temperature preference end

40 final preferendum bluegill guppy chum salmon
10
10
Acclimation temperature C
40 end

• few fishes--tunas & lamnid sharks
• fish are active --generate heat
• rete mirabile for heat exchange & conserv.
• fish are large--low surface area to mass ratio
– body surf. area increases as square of length
– body mass increases as cube of length end

rete mirabile skin gills skin body heat

Counter-current blood flow high venous blood from body heat arterial blood from gills low
Distance along capillaries (rete) end

• fluid flowing in opposite directions
• exchange of heat or gas perpendicular to flow
• efficiency versus speed end

Hypothetical Co-current blood flow: from body high counter-current venous blood arterial blood from gills low
Distance along capillaries (rete) end

• fluid flowing in same direction
• exchange of heat or gas perpendicular to flow
• speed versus efficiency end