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Comparative physiology
Lecture -3Oxygen
(Respiration )
By : Saib Al owini
P(16-25)
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Four basic respiratory systems
• 1. Diffusion across integument
• 2. Gills: evagenation ( turned out)
May be found in sac
• 3. Lungs invagenation ( turned in)
Pulmonate land snail -1stTerm lung used if meida is air or water
• 4. Tracheae
- Spiracles and trachea
- Blood dosnt transport system
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Respiratory in water
• Small animals
diffusion
• Large animals
respiratory
organs
• Animal without specialized resp organ.
- small sphere : with small respiratory surface
-enlargement by deviation on sphere: large
surface
- O2 Concentration on surface which sufficient
to animal for metabolic ( by diffusion )is
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• FO2= VO2 * R / 6K
FO2= con surface O2 ( as fraction of atm pressure)
VO2 = rateO2 consumption cm3/cm3
R2 = radius
K =diffusion constant
K= cm3 of oxygen that will diffuse /min in area 1cm3 and
1atm
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Example
•
•
•
•
•
Animal has
FO2= ?
VO2 =0.001 ml /g
R2 = 1 cm
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K =11*10
• O2 pressure required = 15 atm (not found)
• If animal 1mm ------- 0.15 atm O2 found
• Aerated Water have 0.21 atm o2
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Animals which use diffusion
•
•
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1- small as protozoa
2- very low metabolic rate as Jellyfish has
Flattened body
1% organic the other are water salts So
has low metabolic
Wide but thin body wide respiratory surface
Active cell on surface no distance diffusion
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• If the animal is larger it will have
• Flattened body
• Or increase respiratory surface
Ex , Sponges , corals
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Animal with respiratory organs
• Diffusion is not suffice.
• Then we found respiratory organs
with
- Large surface
- Thinner membrane
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Animals with respiratory organs
• Four basic respiratory systems
• 1. Diffusion across integument
• 2. Gills: evagenation ( turned out)
May be found in sac
• 3. Lungs invagenation ( turned in)
Pulmonate land snail -1stTerm lung used if meida is air or water
• 4. Tracheae
- Spiracles and trachea
- Blood dosnt transport system
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Effective respiratory organs :
-Large surface
-- thin membrane
-* Gills usually in water
-* lungs usually in air
-
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• Some lunges live in water
Sea cucumber use lung in water
-* Some gills may modified to act in air but
most fish have been Asphyxiated in air.
Water support gills , air cannot so gills tend
to stick together by surface adhesion.
Resulted in decreasing respiratory surface
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Sea Cucumbers are
the only marine
invertebrate with a
true tidal lung that
suctions water in and
then pushes it back
out the same
aperature (Anus)
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Ventilation of gills
• Water must renewal by various mechanisms
1- moving gill through water
- Small organism, some aquatic insects (may
flay larvae).
- Large Energy required to resist water
- Ex, large aquatic salamander mudpuppy
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Gill ventillation
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Ventilation of gills
• 2- moving water over respiratory surface:
More feasible
A- by ciliary's action
Mussel , clams
- Spongy move water by flagella.
B- moving water by mechanical pump like
devise
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Primitive
mollusk
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B- moving water by mechanical pump like
devise
• Fish and crabs
• Low coast
• 3 - movement of animals ( immobile gill
cover)
• Cannt survive without swimming
• Sequid ,octopus take water into mantel
cavity then eject it through siphon
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Gas exchange and water flow
• For active gas exchange :
- Highly active fish have the largest relative
gill area
ex(: fast mackerel has gill surface equal 50
times of bottom living goose fish )
- High rate of water flow
- gill cavity provide protection , permit water
to perfuse over gills.
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Counter current
• Several major gill arches on each side
From each arise two rows of gill filaments
Tips of filament arch meet
Each filament caries densely packed flat
lamella in rows
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-Water flow
between lamella
opposite to blood
flow
-What is the aim!!
-What is the
difference if they
flow together
or cross other !!!
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efferent & afferent arteries
gill
arch
secondary
lamella
filament
secondary
lamella
aff.
water
Scheid and Piiper (1997)
filament
eff.
counter-current flow is key to oxygen 31
extraction efficiency in aquatic respiration
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Oxygen transfer from the environmental medium to
the blood (Part 1)
No respiratory system is designed this way33
by cross-current exchange
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Oxygen transfer from the environmental medium to
the blood (Part 2)
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• Oxygen uptake to blood still even highest
level of o2 reach
• Water will meet blood with lower o2 even
the end
• Water leave with lost of 70 -90 %
• but mammals remove ¼ air initial o2
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Oxygen transfer from the environmental medium to
the blood in a tidally ventilated lung
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• Concurrent :
• Little o2 uptake
• More energy consuming
• Crabs : have low efficiency counter current
Because blood diffusion briar is grater
European shore crab 7-30 extraction
In other crabs 50%
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What is water resistance levels through
the gills?
• Hughes (1966) calculated that flow through
gills of a 150 g tench (Tinca) for a pressure of
5 mm water ~ 10.1 ml/s
• Normal volume of water passed through fish
gills = 1-2 ml/s.( 0.02 mm between lamella)
• Conclusion: Gill lamellae do not offer much
resistance to flow
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How do fish pump water over their
gills?
• Double set of pumps (oral cavity and opercular
cavity)
• Volume of oral cavity can be changed by lowering
jaw (pump 1)
• Volume of second pump changed by increased
movements of opercular flap (pump 2)
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• The pressure in the two cavities are
linked
• Pressure drops when mouth begins to
open; increases as mouth is closed
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Opercular pumping in fish
• Gill chamber is rigid (opercular cavity)
• Can be sealed by a flap (operculum)
• Bottom of the opercular chamber is muscular and can be
raised or lowered
• Pump cycle:
– Mouth open, operculum closed
• Bottom of chamber drops, chamber fills
– Mouth closed
• Bottom of chamber is raised, squeezing water out
through operculum
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Buccal-opercular pump during inhalation
(Eckert, Fig. 13-40)
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Buccal-opercular pump during exhalation
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Ventilation
Buccal-opercular
pumping
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Ram ventilation
• Some fish use water pumping; they survive by
swimming to pass water through gills = ram ventilation
• Some fish species only use ram ventilation (e.g.,
tunas)
• Other species use water pumping at low speeds,
switch to ram ventilation at high speeds
• Fish adjust openings of their mouths to modulate
water flow
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• Example:
• Mackerel swimming in water with less
oxygen opened their mouths more
• The lowered oxygen supply was
compensated by increased water flow
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• Ram ventilation is more economic on high
speed
• If low oxygen mouth opining increase
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Coughing
• Solid particles in water tend to caught in
gills
• Closed lips with enlargement of buccal
cavity lowering pressure
• As coughing in animal
• Crabs revers each 1-10/min
To maintain gills clear .
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