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Comparative physiology

Lecture -3-

Oxygen

(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 -1st- Term 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 * R2

/ 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• K =11*10

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• 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 • 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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• 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 -1st- Term lung used if meida is air or water• 4. Tracheae- Spiracles and trachea - Blood dosnt transport system

Animals with respiratory organs

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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 filamentsTips 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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31Scheid and Piiper (1997)

eff.

aff.

filamentwater

counter-current flow is key to oxygen extraction efficiency in aquatic respiration

gillarch

secondarylamella

filament

efferent & afferent arteries

secondarylamella

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Oxygen transfer from the environmental medium to the blood (Part 1)

No respiratory system is designed this way

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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)13

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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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