Transcript Vertebrate Respiration

Vertebrate
Respiration
Bi 150/150.1
Functions
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Intake and distribution of oxygen, elimination of carbon
dioxide
Passive diffusion: simplest form
Dependent on surface area and difference in partial
pressures
Ventilation – passage of air or water over respiratory
surface
Perfusion – driving of blood through capillaries
Differ with regard to habitat
Unidirectional vs. bidirectional
Basic: Origins of the Organs
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Gills: from pharyngeal slits
Lungs: endodermal outpocketings from the gut
Gas bladders: may be homologous to lungs
Ventilatory Mechanisms
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Ciliatory mechanisms
Muscular mechanisms
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Dual Pump (water ventilation) – in most fishes
Buccal Pump (air ventilation)
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Two-stroke – in air-breathing fishes and most
amphibians
Four-stroke – in some salamanders
Aspiration Pump (air ventilation) – in amniotes
http://ars.els-cdn.com/content/image/1-s2.0-S1095643310000838-gr2.jpg
http://upload.wikimedia.org/wikipedia/commons/thumb/3/35/Two_stroke_buc
cal_pumping.jpg/400px-Two_stroke_buccal_pumping.jpg
http://upload.wikimedia.org/wikipedia/commons/thumb/f/f4/Four_stroke_buccal_pumping.jpg/800px-Four_stroke_buccal_pumping.jpg
http://www.cvphysiology.com/Cardiac%20Function/abdominothoracic%20pump%20animated.gif
Phylogeny of the System
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Elasmobranchii
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Countercurrent flow across gills
Ram ventilation (obligate in some)
First gill slit reduced to spiracle
http://www.shark-info.com/images/respiration.jpg
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Osteichthyes
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Operculum covers the gills
Some use gas bladders (sometimes connected to the
buccal cavity via the pneumatic duct)
http://www.goldfishworld.com/images/gill_gross_view.jpg
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Amphibia
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Gill ventilation as juveniles
Cutaneous respiration and lung ventilation as adults
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Reptilia
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Single central air chamber with faveoli
(compartments that increase surface area and are
sites of gas exchange)
Aspiration (exhalation sometimes passive)
Snake lungs singular and divided into respiratory and
saccular portions
Crocodile livers act as pistons.
Limb movement important in turtles
Journal Article*
Farmer CG, Sanders K. 2010. Unidirectional
airflow in the lungs of alligators. Science
327:338-340.
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Birds
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Passageways branch off into parabronchi
(unidirectional)
With 6-12 (usually nine) avascular air sacs, which
extend into the cores of large bones
Crosscurrent flow
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Mammals
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Extensive use of diaphragm and intercostals
With alveoli (bidirectional)
Viscera also assist in respiration.
Functional considerations
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Types of flow
Ventilation and perfusion rates should be
balanced (ratios depend on ecology)
Metabolic costs of living in water vs. air
Regulation of blood pH levels