This document discusses gas exchange and respiratory organs. It describes how gas exchange occurs across surfaces via diffusion, and how this is enhanced by thin, moist, and well-vascularized surfaces. It then outlines different respiratory organs used for gas exchange, including lungs, gills, and skin in various organisms. It also provides details on lung function in frogs, mammals, and birds.

1. Lecture 5. Gas Exchange
• cellular respiration, oxidative processes within
cells
• external respiration, exchange of O2 and CO2
between the organism and its environment

2. Gas Exchange Surfaces
•
for diffusion to be effective, gas-exchange
regions must be:
–
moist
–
thin
–
relatively large
•
effectiveness of diffusion is enhanced by
vascularization

3. Respiratory Organs
• cutaneous respiration (direct diffusion)

4. Respiratory Organs
• Tracheal systems (branching system of tubes)

5. Respiratory Organs
• Gills or branchia (external or internal)
papulae (dermal branchiae or skin gills)

6. Respiratory Organs
• Gills or branchia (external or internal)
gills in axolotl (Ambystoma mexicanum)
branchial tufts (gills) in marine worm

7. Respiratory Organs
• Gills or branchia (external or internal)
parapodia in ragworm (Nereis spp.)

8. Respiratory Organs
• Gills or branchia (external or internal)

9. How a fish ventilates its gills

10. countercurrent flow/exchange
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12. Respiratory Organs
• Lungs (invaginations)

13. • Lungs of frogs
A frog ventilates its lungs by positive pressure breathing.

14. • Lungs of mammals

15. • Lungs of mammals
Mammals ventilate their lungs by negative pressure breathing.

16. • Lungs of birds
http://www.peteducation.com/article.cfm?c=15+1829&aid=2721

17. • Lungs of birds
http://www.peteducation.com/article.cfm?c=15+1829&aid=2721

18. •
the volume of air an animal inhales and exhales
with each breath is called tidal volume
–
it averages about 500 mL in resting humans
•
the maximum tidal volume during forced
breathing is the vital capacity
–
about 3.4 L and 4.8 L for college-age females and
males, respectively

19. •
most animals transport most of the O2 bound
to special proteins called respiratory pigments
–
hemocyanin
–
hemoglobin

20. •
when the
control center
registers a slight
drop in pH, it
increases the
depth and rate
of breathing,
and the excess
CO2 is
eliminated in
exhaled air

21. •
O2 diffuses into pulmonary
capillaries
•
most O2 combines with
hemoglobin in red blood cells
to form oxyhemoglobin
•
CO2 diffuses out of
pulmonary capillaries
•
most CO2 is transported in
the form of bicarbonate ion
•
some CO2 combines with
hemoglobin to form
carbaminohemoglobin

22. Fig. 31.27

23. •
cooperative oxygen binding and release is evident in the
dissociation curve for hemoglobin

24. •
a drop in pH lowers the affinity of hemoglobin for O2, an
effect called the Bohr shift