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THIRD EDITION
HUMAN PHYSIOLOGY
AN INTEGRATED APPROACH
Dee Unglaub Silverthorn, Ph.D.
Chapter 18, part A
Gas Exchange and Transport
PowerPoint® Lecture Slide Presentation by
Dr. Howard D. Booth, Professor of Biology, Eastern Michigan University
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
About this Chapter
• Getting CO2 & O2 dissolved for transport
• How oxygen is transported, role of hemoglobin
• How carbon dioxide is transported
• Regulators that sense and coordinate respiration
with circulation for gas transport
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Overview of Respiratory Exchange
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 18-1: Overview of oxygen and exchange and Transport CO2
Solubility of Gasses
• Pressure gradient: lower at high altitudes
• Temperature: constant in warm blooded humans
• Solubility (solute & solvent): O2 or CO2 in water
Figure 18-2: Gases in solution
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Gas Exchange in the Lungs and Tissues: Oxygen
• Diffusion through alveolar thin cells
• Down diffusion gradient
• Higher in alveoli
• Lower in blood
• Diffusion from blood
• Also down gradient
• To ECF
• To tissue cells (convert O2 to CO2)
PLAY
Animation: Respiratory System: Gas Exchange
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Gas Exchange in the Lungs and Tissues: Oxygen
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 18-3a: Gas exchange at the alveoli and cells
Gas Exchange in the Lungs and Tissues:
Carbon Dioxide
• Diffusion out of cells (down diffusion gradient)
• Into blood
• Buffer role
• Conversions:
• Plasma
• Bicarbonate
• On Hb
• Into alveolus & expiration
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Gas Exchange in the Lungs and Tissues:
Carbon Dioxide
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 18-3b: Gas exchange at the alveoli and cells
Alveolar Exchange and Diseases Related to
Exchange
• Wet surface
• Thin epithelia
• Little ECF
• Diseases:
• Emphysema
• Fibrotic Lung
• Pulmonary edema
• Asthma
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Alveolar Exchange and Diseases Related to
Exchange
Figure 18-5: Oxygen diffuses across the alveolar and endothelial cells to enter the plasma
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Overview of Hemostasis:
Clot Formation & Vessel Repair
Figure 18-4: Pulmonary pathologies that affect alveolarventilation and gas exchange
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Gas Transport in the Blood: Oxygen
• 2% in plasma
• 98% in
hemoglobin (Hb)
• Blood holds O2
reserve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Figure 18-6: Summary of oxygen transport in the blood
Gas Transport in the Blood: Oxygen
Figure 18-7 : The role of hemoglobin in oxygen transport
PLAY
Animation: Respiratory System: Gas Transport
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Hemoglobin Transport of Oxygen:
Disassociation Curve
• 4 binding sites per Hb molecule
• 98% saturated in alveolar arteries
• Resting cell PO2 = 40 mmHg
• Working cell PO2 = 20 mmHg
• More unloaded with more need
• 75% in reserve at normal activity
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings
Hemoglobin Transport of Oxygen:
Disassociation Curve
Figure 18-8: Oxygen-hemoglobin dissociation curve
Copyright © 2004 Pearson Education, Inc., publishing as Benjamin Cummings

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