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Respiratory System Gas Transport by the Blood Xinping Yue [email protected] Department of Physiology LSUHSC-NO. At Standard Barometric Pressure. O 2 = 40 torr CO 2 = 45 torr. O 2 = 100 torr CO 2 = 40 torr. Gas Transport. O 2 = 150 torr CO 2 = 0 torr. - PowerPoint PPT Presentation
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Respiratory System Gas Transport by the Blood
Xinping [email protected]
Department of PhysiologyLSUHSC-NO
At Standard Barometric Pressure
Dry Atmospheric Gas (P)
Inspired Gas (PI)
Alveolar Gas (PA)
Mixed Expired Gas (PE)
Po2 159.0 mmHg 149.0 mmHg 104.0 mmHg 120.0 mmHg
Pco2 0.3 mmHg 0.3 mmHg 40.0 mmHg 27.0 mmHg
PN2 600.6 mmHg 564.0 mmHg 569.0 mmHg 566.0 mmHg
PH2O 0 mmHg 47.0 mmHg 47.0 mmHg 47.0 mmHg
O2 = 150 torrCO2 = 0 torr
O2 = 150 torrCO2 = 0 torr
O2 = 100 torrCO2 = 40 torr
O2 = 100 torrCO2 = 40 torr O2 = 100 torrCO2 = 40 torr
O2 = 40 torrCO2 = 45 torrO2 = 40 torrCO2 = 45 torr
Gas Transport
Transport of O2 by the bloodTransport of O2 by the blood
Physically dissolved
•At 37°C, 1 ml of plasma contains 0.00003 ml O2/mm Hg PO2
•Normal arterial blood contains 0.3 ml O2/100 ml
Chemically combined to hemoglobin
•1 gram of hemoglobin can combine with 1.34 ml of O2 when fully saturated
•A person with 15 g Hb/100 ml of blood can carry 20.1 ml O2/100 ml blood
% Hb saturation = x 100%O2 bound to Hb
O2 capacity of Hb
Hemoglobin, human, adult(heterotetramer, (αβ)2)
The protein's α and β subunits are in red and blue, and
the iron-containing heme groups in green
Heme b group
Oxyhemoglobin Dissociation CurveOxyhemoglobin Dissociation Curve
Bohr effect
Hem
oglo
bin
satu
ratio
n, %
Hem
oglo
bin
satu
ratio
n, %
Partial pressure of oxygen, mm HgPartial pressure of oxygen, mm Hg
2020
4040
6060
8080
100100
20
40 60 80 100 120 140 160
P50P50
50%50%
Pco2 , pH
temp, BPG
Pco2 , pH
temp, BPG
Cyanosis
• Occurs when more than 5 grams of hemoglobin/100 ml of arterial blood are in the “deoxy” state
• Absence of cyanosis does not rule out hypoxemia (anemia)
• Presence of cyanosis does not always indicate hypoxemia (polycythemia)
Transport of CO2 by the bloodTransport of CO2 by the blood
Physically dissolved (5-10%)
•At 37°C, 1 ml of plasma contains 0.0006 ml CO2/mm Hg PCO2
•Normal arterial blood contains 2.4 ml CO2/100 ml
Carbamino compounds (5-10%)
Bicarbonate (80-90%)
CO2 + H2OCO2 + H2O H2CO3H2CO3 H+ + HCO3H+ + HCO3
CarbonicAnhydraseCarbonic
Anhydrase-
CO2CO2 (Gas phase)
(Dissolved in the aqueous phase)
R - N + CO2 R - N + H+R - N + CO2 R - N + H+
H
H
H
H
H
COO-
H
COO-
Terminal amine group
Carbamino compoundCarbamino compound
Carbamino CompoundCarbamino Compound
Carbon Dioxide Dissociation CurveCarbon Dioxide Dissociation Curve
Haldane effect
A Classification of the Causes of HypoxiaA Classification of the Causes of HypoxiaIncreased
FIo2
helpful?Classification PAo2
Pao2 Cao2 Cvo2Pvo2
Hypoxic hypoxia
Low alveolar Po2
Diffusion impairment
Right to left shunts
V/Q mismatch
Anemic hypoxia
CO poisoning
Hypoperfusion hypoxia
Histotoxic hypoxia
Low
Norm
Norm
Norm
Norm
Norm
Norm
Norm
Low
Low
Low
Low
Norm
Norm
Norm
Norm
Low
Low
Low
Low
Low
Low
Norm
Norm
Low
Low
Low
Low
Low
Low
Low
High
Low
Low
Low
Low
Low
Low
Low
High
Yes
Yes
No
Yes
No
Possibly
No
No