1. Gas Exchange and Transport
Chapter 18, part A
Gas Exchange and Transport

2. 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

3. Overview of Respiratory Exchange
Figure 18-1: Overview of oxygen and exchange and Transport CO2

4. Figure 18-2: Gases in solution
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

5. 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

6. Gas Exchange in the Lungs and Tissues: Oxygen
Figure 18-3a: Gas exchange at the alveoli and cells

7. 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

8. Gas Exchange in the Lungs and Tissues: Carbon Dioxide
Figure 18-3b: Gas exchange at the alveoli and cells

9. Alveolar Exchange and Diseases Related to Exchange
Wet surface
Thin epithelia
Little ECF
Diseases:
Emphysema
Fibrotic Lung
Pulmonary edema
Asthma

10. Alveolar Exchange and Diseases Related to Exchange
Figure 18-5: Oxygen diffuses across the alveolar and endothelial cells to enter the plasma

11. Overview of Hemostasis: Clot Formation & Vessel Repair
Figure 18-4: Pulmonary pathologies that affect alveolarventilation and gas exchange

12. Gas Transport in the Blood: Oxygen
2% in plasma
98% in hemoglobin (Hb)
Blood holds O2 reserve
Figure 18-6: Summary of oxygen transport in the blood

13. Gas Transport in the Blood: Oxygen
Figure 18-7 : The role of hemoglobin in oxygen transport
PLAY
Animation: Respiratory System: Gas Transport

14. 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

15. Hemoglobin Transport of Oxygen: Disassociation Curve
Figure 18-8: Oxygen-hemoglobin dissociation curve