Comparative Respiratory
Systems
The function of animal respiratory systems is to…
AND to…
It’s all about DIFFUSION!!!
Skin Diffusion
(in Invertebrates)
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Thin layer of skin cells
Moist/wet for gas diffusion
Blood vessels close to the skin
Gas exchange by diffusion
• Oxygen in
• Carbon Dioxide out
• Example Organisms:
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Flat worms
Round worms
Segmented worms
Jellies
Sponges
Mollusks
• Bivalves
• Snails
• Cephalopods
Gills (in Annelids)
• Small thin branches
• Lined with blood vessels
• Gas exchange by diffusion
• Oxygen in
• Carbon Dioxide out
• Example Organisms:
• segmented worms
• leaches
• earthworms
• Feathery structure just under
the mantle (under the shell)
• Lined with blood vessels
• Gas exchange by diffusion
• Oxygen in
• Carbon Dioxide out
• Example organisms:
• Mollusks:
• Bivalves (clams, mussels, etc.)
• Gastropods (snails, slugs)
• Cephalopods (octopus, squid, etc.)
Mantle Cavity Gills
(in Mollusks)
• Spiracles
• Holes along abdomen
• How air gets into the body
• Tracheal Tubes/Tracheoles
• Tubes that carry air throughout body
• Air Sacs
• Reservoirs of air; push air through
tracheal tubes when contracted
• Gases are moved, to a large extent,
by pumping actions of the body
segments; no blood flow needed.
Respiratory System
(of Insects)
Respiratory System (of Insects)
• Hemolymph (i.e. arthropod blood)
seeps into tracheoles in periods of
low activity.
• Fluid/gas interface gas exchange
• Hemolymph pulled out of
tracheoles in high activity
• Gas exchange is nearer to cells
• Respiratory system of insects is what restricts their body size.
(i.e. this system is only efficient for small sizes up to diameter of 3 cm.
Book Lung (in Arachnids)
• Found inside an air-filled
cavity (atrium) in underside
of the abdomen.
• Hemolymph (i.e. arthropod
blood) flows between the
layers of air pockets
(lamellae) for gas exchange.
• Stacks of alternating
lamellae and tissue filled
with hemolymph look
similar to a folded book.
Gills (in Fish)
The Gills of a Tuna fish
Gills (in Fish)
• Gills have a highly-folded feathery structure
• Gill filaments are hair-like projections
• Filaments extend off 3-7 gill arches
• Lined with capillaries (smallest blood vessels)
• Counter current for efficient gas exchange
• Operculum
• Flap that covers/protects gills
• Opens when water is pushed through gills
• Buccal cavity (mouth)
• Forces water past gills
Amphibian Skin (only in water) & Gills (sometimes)
Skin: similar to invertebrate
structure and function
Gills: similar to fish in
structure and function
Amphibian Lungs
• Lungs
• modified air sacs
• Folded inner surface to…
• Lined with small blood vessels
• Gas exchange
Avian (bird) Respiratory System
• The Avian respiratory system is
similar to that of Mammals, with
two key differences:
1. Air sacs (9 of them) which
expand on inhalation and
contract on exhalation,
allowing for…
Avian (bird) Respiratory System
2. One-way flow:
air moving
through lungs is
constant “fresh”
air with higher
O2 content.
• Avian lungs are the
only site of gas
exchange, air sacs
just move the air
through the system.
Mammalian
Respiratory System
• The nasal cavity is lined with
hair to filter inhaled air; also
warms and humidifies air.
• Air is directed to alveoli (air
sacs in the lungs) through
branching network of tubes
• Trachea, Bronchi, Bronchioles
• Alveoli have very thin layer
of cells (1 or 2 deep) with
capillaries all around for
maximized gas exchange.
References
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http://www.bozemanscience.com/respiratory-system
http://spice.duit.uwa.edu.au/samples/ast0842/specific/images/diving_animals/anatomy/snake_03.png
http://aibara.tripod.com/rdiag.jpg
https://www.youtube.com/watch?v=W7Efjt6UC1g
http://media-2.web.britannica.com/eb-media/14/55014-004-B80B2BEF.jpg
http://classconnection.s3.amazonaws.com/38/flashcards/1293038/png/fish_gills1336075212422.png
http://www.amentsoc.org/insects/fact-files/respiration.html
http://www.loganaskwhy.com/notes_reviews_handouts/Bio%20PPT%20Files/Chapter30LoganBio_files/slide
0052_image074.jpg
http://www.brown.edu/Departments/Engineering/Courses/En123/MuscleExp/ImgSource/frog_gas_exchang
e.gif
http://www.paulnoll.com/Oregon/Birds/Avian-Respiratory.jpg
http://science.kennesaw.edu/~jdirnber/Bio2108/Lecture/LecPhysio/42-25-BirdRespiratorySys-CL.jpg
http://people.eku.edu/ritchisong/birdrespiration.html