1. The Respiratory System: Gas Exchange and Regulation of Breathing

2. O2 and CO2 Movement Figure 17.1
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3. Partial Pressure Ptotal = P1 + P2 + P3 + … Pn
Partial pressure of a gas depends on
Fractional concentration of the gas
Total pressure of gas mixture
Pgas = %gas x Ptotal
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4. Gas Composition of Air Pair = 760 mm Hg = PN2 + PO2
PN2 = 0.79 x 760 mm Hg = 600 mm Hg
PO2 = 0.21 x 760 mm Hg = 160 mm Hg
Air is only 0.03% carbon dioxide
PCO2 = x 760 mm Hg = 0.23 mm Hg
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5. Composition of Air at 100% Humidity
Pair = 760 mm Hg = PN2 + PO2+ PH2O
PN2 = x 760 mm Hg = 563 mm Hg
PO2 = x 760 mm Hg = 149 mm Hg
PH2O = x 760 mm Hg = 47 mm Hg
PCO2 = x 760 mm Hg = 0.21 mm Hg
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6. Solubility: Henry’s Law
c = kP
c = molar concentration of dissolved gas
k = Henry’s Law constant
P = partial pressure of gas in atmospheres
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7. Solubility of O2 Figure 17.3a
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8. Solubility of CO2 Figure 17.3b
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9. O2 and CO2 Partial Pressures
Figure 17.4
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10. O2 and CO2 Partial Pressures
Table 17.1
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11. Pulmonary O2 Exchange Figure 17.5a
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12. Pulmonary CO2 Exchange Figure 17.5b
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13. Respiratory Terms Table 17.2
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14. Oxygen Transport in the Blood
Oxygen not very soluble in plasma
Thus only 3.0 mL/200 ml arterial blood oxygen dissolved in plasma (1.5%)
Other 197 mL arterial blood oxygen transported by hemoglobin
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15. Forming Oxyhemoglobin
Figure 17.6a
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16. Dissociation of O2 from Hemoglobin
Figure 17.6b
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17. Saturation of Hemoglobin with O2
Arterial blood
Hemoglobin is 98.5% saturated
Figure 17.7a
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18. Saturation of Hemoglobin with O2
Venous blood
Hemoglobin is 75% saturated
Figure 17.7b
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19. Oxygen Dissociation Curve
Figure 17.8
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20. Effects of O2 Affinity Changes
Shift right
Less loading of O2
And less unloading
Shift left
More loading of O2
Figure 17.9
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21. Temperature Effects: O2 Saturation
Higher temperature
Active tissues
Shift right
More O2 unloading in tissues
More O2 delivery to tissues
Figure 17.10a
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22. pH Effects: O2 Saturation
Bohr effect
Lower pH increases O2 unloading
Active tissues
Produce more acid pH decreases in tissues
Decreased pH causes shift right in saturation curve
More O2 is unloaded to tissues
Figure 17.10b
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23. Carbon Monoxide
Hemoglobin has greater affinity for carbon monoxide (CO) than for oxygen
Prevents oxygen from binding to hemoglobin
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24. CO2 Transport in Blood Table 17.3
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25. Carbon Dioxide Transport in Blood
The role of carbonic anyhdrase in carbon dioxide transport
Carbon dioxide exchange and transport in systemic capillaries and veins
Carbon dioxide exchange and transport in pulmonary capillaries and veins
Effect of oxygen on carbon dioxide transport
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26. Carbon Dioxide Transport Mechanisms
Although carbon dioxide is more soluble in plasma than oxygen, it is still not very soluble
5–6% transported dissolved in plasma
Carbon dioxide can bind to hemoglobin to form carbaminohemoglobin
5–8% transported bound to hemoglobin
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27. Carbon Dioxide Transport Mechanisms
Can be converted to bicarbonate by erythrocytes, then transported into plasma
86–90% transported dissolved in the plasma as bicarbonate
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28. Carbonic Anhydrase CA CO2 + H2O  H2CO3  H+ + HCO3-
Enzyme that converts carbon dioxide and water to carbonic acid
Law of Mass Action: An increase in CO2 causes an increase in bicarbonate and hydrogen ions
CO2 + H2O  H2CO3  H+ + HCO3- CA
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29. CO2 Exchange: Tissues Figure 17.11a
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30. CO2 Exchange: Lungs Figure 17.11b
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31. PO2 Effect on CO2 Transport
Figure 17.12
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32. Tissues: CO2 Loading/O2 Unloading
Figure 17.13a
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33. Lungs: CO2 Loading/O2 Unloading
Figure 17.13b
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