Download Comparative Physiology Part II Terrestrial Gas Exchange Terrestrial

Comparative Physiology
Aquatic and Aerial Respiration
Part II
Terrestrial respiration
Terrestrial Gas Exchange
• Some air breathing adaptations in
– Platyhelmintheyes, annelida, arthropoda, gastropoda,
vertebrata
– Flatworms, earthworms, leeches have no special respiratory
structures
– Gasses exchanged across the body wall
– Skin must remain moist – limited to moist habitats
Terrestrial Gas Exchange
• Gastropods, terrestrial arthropods, and vertebrates
have specialized respiratory structures
– Can inhabit dry and moist habitats
– Arthropods have a tracheal system
– Gastropods and arthropods also have lungs
Gas Exchange in Terrestrial Animals
• Three types of Lungs
– Ventilation lungs
• Move air in and out by a pumping mechanism
– Diffusion lungs
• Snails and slugs have a pneumostome which opens to a mantle well supplied with
circulatory fluid
– Book lungs
• Diffusion lung found in spiders shaped like pages of a book. Found in abdomen and
open to the atmosphere on the ventral surface. Ventilated by body movements and
general activity
Book lungs
Gastropod Respiration
Gas Exchange in Terrestrial Animals
• Invertebrates
– Insects
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Large surface area to volume ratio
Highly susceptible to drying
Covered by cuticle with waxy layer
Tracheal system accounts for most gas exchange
Spiracles, tracheae, tracheoles
Gas Exchange in Terrestrial Animals
• Tracheal system accounts for most gas exchange
• Air enters through spiracles
– Hydrophobic hairs prevent dust and water entry
• Spiracles open into the tracheae
• The largest tubes in the system, cuticle lining holds them open
• Trachea divide into tracheoles which end in blind, liquid filled
tubules
– As metabolites fill the fluid, water and gasses are drawn deeper
into the tracheoles, increasing gas exchange in active tissues
Gas Exchange in Terrestrial Animals
• In small insects, diffusion is sufficient
• In large insects, Air sacs located near large muscles achieve pumping in
the system
Gas Exchange in Terrestrial Animals
– Aquatic insects
• Tracheal system can extract oxygen from water or air
– Tracheal gills- dense networks of fine trachea in featherlike
extensions from the body
Insect
Tracheal
System
Gas Exchange in Terrestrial Animals
• Amphibians
Gas Exchange in Terrestrial Animals
Gas Exchange in Terrestrial Animals
• Vertebrates
– Amphibians
• Buccal pumping
• Trachea, glottis, bronchus
• Cutaneous gas exchange
Gas Exchange - Buccal pumping 1
Gas Exchange - Buccal pumping 2
Gas Exchange - Buccal pumping 3
Gas Exchange - Buccal pumping 4
Gas Exchange in Terrestrial Animals
• Vertebrates
– Mammals
• Higher metabolism requires more oxygen per unit of body weight to
maintain homeostasis
• Lungs provide efficient ventilation and greater surface area
Terrestrial vertebrates: Lungs
Terrestrial vertebrates: Lungs
• Nostrils filter air
• Nasal passages adjust temp
• Larynx
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Trachea and bronchi supported by cartilage rings
Broncus divide into bronchioles which end in clusters of alveoli
30,000,000 alveoli per 75 KG person!
15x more area than frog
Ciliary escalator to clean system
Gas Exchange in Terrestrial Animals
• Vertebrates
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Birds
Parabronchi
Air capillaries
Air sacs
Crosscurrent exchange
Breathing
Breathing ventilates the lungs
• Inhalation
– Ribcage expands, diaphragm contracts, chest expands - lungs
increase in size - air flows into the alveoli from higher
pressure outside.
• Exhalation
– Rib and diaphragm muscles relax- chest contracts, lungs
decrease in size -air forced out.
Birds have highly efficient, flow through
lungs
Birds have highly efficient, flow through
lungs
• One - way air flow through the lungs
• Air sacs ventilate respiratory surface in the lungs
• Inhalation- posterior sacs fill with fresh air- anterior sacs fill
with stale air
• Exhalation - both sacs deflate forcing air into the lungs and out
of the system
• No alveoli, parallel tubes, crosscurrent exchanger, more
efficient than mammalian lung
Control over breathing
Control over breathing
Gas Transport and Body Fluids
• Respiratory pigments
– Functions
• Hemacyanins
– Mollusca and arthropoda, based ion Copper
• Hemoglobins
• Myoglobin
Gas Transport and Body Fluids
• Respiratory pigments
– O2 binding to Hemoglobin
– Cooperativity
– Bohr effect
Quiz
• Read Withers 608-645
• Make a chart that compares the respiratory systems of
the terrestrial organisms found in this chapter
• Be thorough!
Adaptations in Diving Mammals
• Weddell seal
– 300-500M dives for up to 15 minutes
• Whales
– 500M dives for up to 1 hour
• Problems:
– Oxygen demand and the bends
Adaptations in Diving Mammals
• Bends
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N2 from air dissolves in blood
Surface too quickly
N2 bubbles in blood like carbonated soda
Capillaries blocked and ruptured, pain, brain seizures possible
• Divers must ascend slowly!
• Whales and seals come up fast?
Adaptations in Diving Mammals
• Whales and seals come up fast?
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Prevent high pressure air from contacting blood
Exhale before dive
Pressure collapses trachea and lungs, air removed
Store oxygen!
• 2x blood per unit of body weight
• Myoglobin storage
– Diving response
• Slow heart rate to ½ to 1/10 normal rate
• Anaerobic metabolism