Transcript Gas Exchange in Animals - Western Washington University

1. This is wrong. This
book says that
vertebrates use Hb &
arthropods use
hemocyanin (Cu-based)
as their respiratory
pigment.
3. This
insect must
be an
endotherm
with a high
BMR & high
O2 demand.
2. Hmm… Zee
insect obviouzly ‘as
trrouble sustaining
aerrobic rezpiracion
in zee wadairr.
4. I think
maybe the
insect
stores O2
in this
way.
The aquatic air-breathing insect Notonecta has tracheal cells
(cells lining the respiratory passages) that contain
hemoglobin. What advantage would this metallo-protein
serve in a diving, air-breathing insect?
Gas
Exchange
in Animals
Describe the 4
functional
processes involved
in most animal
respiration.
Compare to gas
exchange in plants.
Respiratory Organs
Identify each type
of respiratory
adaptation, and
relate to lifestyle.
Compare (if applicable) ventilation, gas exchange at the respiratory organ,
transport of gases, and gas exchange at the tissues.
Challenges of Gas Exchange related
to Environment
Air vs. Water:
• 20X more oxygen in air than in water (at
the same temp.)
• Diffusion of gas molecules is more rapid in
air
• Air is less viscous than water
– ventilation (air) requires 1/10 the energy of
water breathing
Diversity
in gills
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•Describe the dual
function of gills in
bivalves and
polychaetes.
•Two of these
animals utilize
structures for body
movement in gas
exchange as well.
Describe.
Gill Structure in Fish
p. 983
If fish gills are so efficient at gas exchange, why can’t most fish survive
out of water?
Gill Ventilation in Fish
In order to have
bulk flow of water
over the
respiratory
surface, what
must be created?
Discuss the negative pressure component in gill ventilation.
Discuss the positive pressure component of gill ventilation.
Countercurrent Mechanism for
Gas Exchange
p. 984
Nearly 80% of the O2 is
removed from the water
as it passes over the gills.
Is this more or less
efficient than gas exchange
at the lungs? Why ?
Draw a similar picture showing blood flow and water flow in the
same direction. How would oxygen diffusion change?
Tracheal System in Insects
(May serve as
storage reserve)
Each cell has a nearly direct means
of gas exchange via the tracheal system
(2-4 spiracles on the thorax, 6-8 on abdomen).
What is the advantage of such a
system for a small, fast animal?
Do insects have respiratory pigments in
their hemolymph? Significance?
p. 984
The abdomen in large, active insects like grasshoppers, is used like a bellows to
force air out of tracheae with contraction of skeletal muscles.
What happens when these muscles relax?
The experiment illustrated (first performed by the insect physiologist Gottfried
Fraenkel) shows that there is a one-way flow of air through the grasshopper.
The liquid seals at either end of the tubing move to the right as air enters the first
four pairs of spiracles in the thorax and is discharged through the last six pairs in
the abdomen.
Rubber diaphragm
Liquid seal
Liquid seal
(air)
(air)
How is this different from ventilation in mammals? How does it compare to
ventilation in birds? Explain.
Mechanics of
Respiration:
positive pressure
breathing
Do amphibians have
completely separate
pulmonary and systemic
circulatory systems?
What other organ(s) may be
used in respiration?
Ventilation in Birds
p. 987
Compare the size and complexity of the respiratory system in birds and
amphibians (previous slide), and explain any differences.
Compare the direction of airflow in birds and mammals. What does this
imply regarding the pressure gradients at the transport epithelium?
Mammalian Respiratory System
p. 985
Mechanics of Respiration:
negative pressure breathing
p. 986
How do the serous membranes that cover the surfaces of the lungs
and line the thoracic cavity facilitate breathing?
Gas Exchange
at Lungs
Four factors affect the rate of
gas diffusion across a
selectively permeable
barrier:
1. Solubility of the gas in the
membrane
2. Thickness of the membrane
3. _____________________
4. _____________________
The Function of
Hemoglobin
Would you expect insects (tracheal
system) to have a respiratory pigment
in their hemolymph? Explain.
Hemoglobin is the only respiratory pigment in vertebrates, but it is
a common respiratory pigment among invertebrates as well.
Hemocyanin, a blue copper-containing protein, carries oxygen in
crustaceans and most mollusks, within hemolymph. Describe the
respiratory organs in these animals.
Hemoglobin Dissociation Curves
•How is the function of Hb similar to that of enzymes?
•Under what conditions does Hb act as a strong acid…as a weaker
acid?
Transport
of Carbon
Dioxide
Carbonic anhydrase catalyzes the
chemical reaction in both directions.
Explain how this is possible…
What “drives” the diffusion of
bicarbonate out of RBCs?
Is there a “potential” problem
associated with the loss of HCO3- ?
(pun intended )
p. 992