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Prepared by: Steve Guzman
Gas ExchangeGas ExchangeGas ExchangeGas Exchange
Overview of Gas Exchange
Diagram 1: The three phases of gas
exchange
Animals exchange O2
and CO2 across moist body surfaces
Figure 1: The entire outer skin of
an earth worm serves as its
respiratory surface
Figure 2: Gills are extensions of
the surface that function with the
surrounding water
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Animals exchange O2
and CO2 across moist body surfaces (cont.)
Figure 3: The tracheal system of
an insect consists of tubes that
extend throughout the body
Figure 4: Lungs are internal
thin-walled sacs
Gills are adapted for gas exchange in aquatic environments
Diagram 2: The structure
of fish gills
The tracheal system of insects provides direct exchange between the air and body cells
Figure 6: A grasshopper in flight
Figure 5: The tracheal system of an insect
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The evolution of lungs facilitates the movement of tetrapods onto land
Figure 7: A cast of a fossil of Tiktaalik. Note the elongated
snout and strong shoulder support
The Human Respiratory System
Diagram 4: The anatomy of the
human respiratory system (left) and
details of the structure of alveoli
(right)
Smoking is a serious assault on the respiratory system
Figure 8: Healthy lungs (left) and cancerous lungs (right)
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Negative pressure breathing ventilates our lungs
Diagram 5: Negative pressure breathing
draws air into the lungs
Breathing is automatically controlled
Diagram 6: Control centers
that regulate breathing
respond to the pH of blood
and nervous stimulation
from sensors that detect
CO2 and O2
Blood transports respiratory gases
Diagram 7: Gas transport and
exchange in the body
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Hemoglobin carriers O2, helps transport CO2, and buffers the blood
Figure 8: Hemoglobin loading and unloading of O2
The human fetus exchanges gases with the mother’s bloodstream
Figure 9: A human fetus
and placenta in the uterus