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Gas Exchange Part 1
Begins
Tell me how I’m supposed to breathe with no air?
Got me out here in the water so deep
Tell me how you gon be without me?
If you ain’t here I just can’t breathe
There’s no air no air
You get the idea. Hi, I’m Mr. Lung and I’m here to
present the gas exchange system. Of course, I’m not the
only method of exchanging gases, but for our singers and
you too I perform a very vital function. Just think; How
long can you survive without oxygen? Can you hold your
breath even for a minute? Now consider how important I
am to you, given that I am the organ responsible for
getting that oxygen to your cells and removing the waste
carbon dioxide.
You are probably wondering what happens to the oxygen. CELLULAR
RESPIRATION is the process that actually requires the oxygen and uses it to
release the energy in foods as ATP. The waste gas produced as a result of
the energy release is carbon dioxide. Thus carbon dioxide is released by cells
as a waste gas.
Oxygen in
Carbon dioxide out
In order to conduct gas exchange,
three criteria have to be met
The membrane must:
be thin
have a large surface
area.
be moist.
Different organisms use different methods to accomplish gas
exchange. Differences in RESPIRATORY MEDIUM (the source of O2)
make certain structures more efficient.
Hi I’m Mr. Amoeba. I’m a protist and I do not have any specialized gas
exchange structures, I just use diffusion. I live in water so my membrane is
moist to allow for gas exchange and I am a single celled so I have a large
surface area to volume ratio with only the thin plasma membrane
forming the barrier. My fellow protists conduct gas exchange like I do but
I also have some friends that exchange using only diffusion also ........
flatworm
Phylum platyhelminthes
sponges
Phylum Porifera
jellyfish
hydra
Phylum cnideria
coral
In aquatic environments, gills are useful for gas exchange. Here
are some examples of organisms that are classified as having gills
you may not be aware of.
Watch this Spongebob
episode for some fun.
I have no
nose, thus
no smell. I
breath
through
projections
in my skin
Sea star
Phylum echinodermata
Papullea are tubular
projections of the skin
that conduct gas
exchange (gills)
Scallop
Marine worm
Phylum annelid
Class polychaetes
Parapodia (used for gas
exchange) are the
projections you can see
sticking out of the sides
of the segmented worm
(gills)
Phylum mollusca
Class bivalia
Scallop gills
long projecting
plates with cilia
that circulate
the water.
Crayfish
Phylum
arthopods
Class crustacea
Feathery gills
covered by
carapace
(exoskeleton)
Structures drive
water over the
gills
Since levels of O2 are low in water, ventilation is
necessary.
VENTILATION? What is ventilation Mr. Lungs?
Ventilation is increasing the respiratory medium
over the respiratory surface.
Speak English Mr. Lungs.
Oh yes. I knew that Mr. Lungs.
It means that pushing water over your
gulls increases the amount of O2 and
CO2 you can exchange through the gills.
Mr. Crabs pushes water over his gills by
using special paddle-like structures.
Water contains less than 1% oxygen (4-8 ml dissolved oxygen
per liter) and there is even less in warmer water or saltier
water. This makes ventilation necessary to move water over
the gill surface. Crabs spend considerable energy paddling
water across their gills.
In order to ventilate my gills with water, I gulp water, close my
mouth and push the water over my gills, My operculum opens to
allow the water out.
I’m a shark and I can’t ventilate my gills the same as
the other fish. I have no operculum , cannot gulp
water and must constantly swim to push water
across my gills (RAM VENTILATION).
NEWSFLASH
VIRGIN SHARKS GIVE BIRHT TO YOUNG
(PARTHENOGENESIS)
Recent studies have shown that female sharks are
capable of asexual reproduction!
Mammals, now the only group not capable of
asexual reproduction.
DID YOU KNOW?
Hey, that’s my purse.
The mermaid’s purse is an empty egg
case of the shark pups.
So how come a fish out of water cannot get oxygen. After
all, air has 21% oxygen compared to less than 1% in water.
Surely the gill should work in air given the vastly greater
oxygen.
Once the gills are out of water,
the filaments collapse. This
dramatically decreases the
surface area for gas exchange.
Normally water suspends the
filaments.
In addition, the membrane
moisture must be maintained
in order to exchange gases,
and gills dry out quickly. Fish
suffocate in air.
THE COUNTERCURRENT
EXCHANGE SYSTEM OF FISH
Lowest
oxygen
40%
25%
60%
Highest
oxygen
level
80%
100%
45%
65%
85%
Exchange ?
The fish blood more
effectively extracts O2 from
water by maintaining the
entire exchange surface with
a diffusion gradient drawing
O2 in. Efficiency allows
absorption of more than 80%
of dissolved O2
Dissolved oxygen content
Front of
gill
Blood oxygen content
Let’s get out of the water now and into a terrestrial
environment.
Spiders are not
insects and they have
book lungs often
hooked together to
tracheal systems.
Book lung air spaces
Insects use the tracheal
system of gas exchange. Air
moves directly into the
insect body by a series of
tubes called tracheae. These
tubes end at terminal ends
supplying virtually all body
cells. The terminal ends
have a moist respiratory
lining that allows for gas
exchange. The openings to
the tubes are called
spiracles.
You think you can stop me by plugging my nose and
mouth?. I don’t have a nose and my mouth is strictly
for digestion. You are a fool to think my gas exchange
is conducted by structures on my face!!
Uh oh!
Hopper, we do know an
effective way of destroying
your ability to exchange
gases. You see, we have
some soapy water spray
that if we apply it to your
body will coat your spiracles
and trachea with a thin
layer bubble that will
restrict the passage of gases
to your body cells. Works on
all insects and spiders!!
Insects can increase the efficiency of their tracheal gas exchange
system by ventilating with body contractions. Some flying insects,
ventilate with each wing movement, like a bellows action. They
also have muscles very rich in mitochondria to keep up with the
rapid use of oxygen with this high metabolic rate.
Bees beat their wings approximately 200
times a second, which is 10–20 times as
fast as nerve impulses can fire. They
achieve this because their thorax muscles
Myth – according to aerodynamic laws, do not expand and contract on each nerve
firing, but rather vibrate like a plucked
the bumblebee should not be able to
rubber band. The buzz sound is made by
fly. It succeeds “by the power of its
own ignorance.”This does not consider the muscles, not the wings and can be
dynamic stall and the vortex created
heard without wing movement when
generating several times normal lift.
decoupled as bees warm themselves up to
Errors is probably due to application
a higher body temperature before flight.
only of simplified oscillating aerofoils.
And now it’s time to talk about lungs.
The lungfish has lungs capable of sustaining
it on land(especially mud) and lobed fins
capable of moving it across seasonal water
holes. The lungs are very primitive, like
hollow balloons.
The amphibians have lungs but they are small
and do not provide a large surface area. They
rely on diffusion across body surfaces for much
of their gas exchange. They ventilate with
positive pressure, pushing air that is gulped into
their lungs. This is accomplished by inflating
the mouth cavity, then raising the floor of the
mouth to force the air into the lungs. NOTE
Diaphragm not involved
Reptiles (with some exceptions) birds and mammals rely
exclusively on the lungs to conduct gas exchange. The lungs are
restricted to one location –the circulatory system connects them
to supply the body with oxygen.
Sorry, but I’m an exception. I use my epithelial linings to
enhance gas exchange.
Someone always has to spoil the party. Well I can tell you I
have lungs and I love them. I love getting the infusion of 21 %
atmospheric oxygen into my body and moving around with
high metabolism.
Gas Exchange Part 1
Ends