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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