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Comparative physiology
Lecture -3Oxygen
(Respiration )
By : Saib Al owini
P(16-25)
1
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
2
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
3
2
• 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
-6
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
5
Animals which use diffusion
•
•
-
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
8
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
9
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
15
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)
16
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
18
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
32
Oxygen transfer from the environmental medium to
the blood (Part 1)
No respiratory system is designed this way33
by cross-current exchange
34
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
37
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%
40
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
41
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
44
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
45
Buccal-opercular pump during inhalation
(Eckert, Fig. 13-40)
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13
Buccal-opercular pump during exhalation
47
14
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
51
• 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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