11/4/20111Prepared by: Steve GuzmanGas ExchangeGas ExchangeGas ExchangeGas ExchangeOverview of Gas ExchangeDiagram 1: The three phases of gas exchangeAnimals exchange O2and CO2across moist body surfacesFigure 1: The entire outer skin of an earth worm serves as its respiratory surfaceFigure 2: Gills are extensions of the surface that function with the surrounding water11/4/20112Animals exchange O2and CO2across moist body surfaces (cont.)Figure 3: The tracheal system of an insect consists of tubes that extend throughout the bodyFigure 4: Lungs are internal thin-walled sacsGills are adapted for gas exchange in aquatic environmentsDiagram 2: The structure of fish gillsThe tracheal system of insects provides direct exchange between the air and body cellsFigure 6: A grasshopper in flightFigure 5: The tracheal system of an insect11/4/20113The evolution of lungs facilitates the movement of tetrapods onto landFigure 7: A cast of a fossil of Tiktaalik. Note the elongated snout and strong shoulder supportThe Human Respiratory SystemDiagram 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 systemFigure 8: Healthy lungs (left) and cancerous lungs (right)11/4/20114Negative pressure breathing ventilates our lungsDiagram 5: Negative pressure breathing draws air into the lungsBreathing is automatically controlledDiagram 6: Control centers that regulate breathing respond to the pH of blood and nervous stimulation from sensors that detect CO2and O2Blood transports respiratory gasesDiagram 7: Gas transport and exchange in the body11/4/20115Hemoglobin carriers O2, helps transport CO2, and buffers the bloodFigure 8: Hemoglobin loading and unloading of O2The human fetus exchanges gases with the mother’s bloodstreamFigure 9: A human fetus and placenta in the
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