uptake of oxygen in lungs
DESCRIPTION
Uptake of Oxygen in Lungs. 120. Alveolar. 100. 80. Diffusing capacity. 60. in blood. Normal. 40. O2. 1/4 Normal. P. 20. 1/8 Normal. 0. 0. 0.25. 0.5. 0.75. time in capillary (sec). Uptake of Oxygen in Lungs with Low Alveolar Po 2. Alveolar. 50. Diffusing capacity. Normal. - PowerPoint PPT PresentationTRANSCRIPT
Copyright © 2006 by Elsevier, Inc.
Uptake of Oxygen in Lungs
Alveolar
Diffusing capacity
0
20
40
60
80
100
120
0 0.25 0.5 0.75
time in capillary (sec)
PO
2 in
bloo
d
Normal1/4 Normal1/8 Normal
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Uptake of Oxygen in Lungs withLow Alveolar Po2
Alveolar
Diffusing capacity
0
25
50
0 0.25 0.5 0.75
time in capillary (sec)
Po2
in b
lood Normal
1/4 Normal1/8 Normal
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Uptake During Exercise
• Increased cardiac output
• Decreased transit time
• Increased diffusing capacity– Opening up of additional capillaries
– Better ventilation/perfusion match
• Equilibration even with shorter time
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Oxygen Transport
• Percent Saturation (no units) HbO2
(Hb+HbO2)
• Content (ml O2/100 ml blood)• absolute quantity of oxygen in blood
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• Dissolved oxygen– Solubility 0.003 ml O2/100 ml blood/mmHg– Normal blood 0.3 ml O2 / 100 ml blood at 100mmHg– Normal oxygen consumption ~250 ml O2/min– Would require 83 L/min blood flow
• Hemoglobin– 97% transported by HBO2 (oxyhemoglobin)
O2 + HB HBO2
Transport of Oxygen in Blood
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• Hemoglobin– 1.34 ml O2/gm Hb
– Normal
• 15 gm Hb/100 ml blood
• 20 ml O2 /100 ml blood
– Anemic
• 10 gm Hb/100 ml blood
• 13 ml O2 /100 ml blood
Transport of Oxygen in Blood
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Hemoglobin Dissociation Curve
Lungs
Tiss
ue
Content
0
20
10
0
20
40
60
80
100
120
0 20 40 60 80 100 120PO2
Per
cen
t Sa
tura
tion
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Right Shift of Dissociation Curve
0
20
40
60
80
100
120
0 20 40 60 80 100PO2
Per
cen
t Sa
tura
tion
pHPCO2
Temp
2-3 DPG
Normal
Shift to right
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Left Shift of Dissociation Curve
0
20
40
60
80
100
120
0 20 40 60 80 100
Per
cen
t Sa
tura
tion
pHPCO2
Temp
2-3 DPG
Normal
Shift to left
PO2
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The Oxygen-Hemoglobin Saturation Curve
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The Effect of pH and Temperature on Hemoglobin Saturation
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A Functional Comparison of Fetal and Adult Hemoglobin
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Dissociation Curve
Values to rememberPO2 (mmHg) Saturation (%) Content
(ml/dl)
0 0 0
20 25 5
40 75 15
100 100 20
Remember this is for a person with 15 gm/dl hemoglobin
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Dissociation Curve
hemoglobin
myoglobin
0
20
40
60
80
100
120
0 20 40 60 80 100 120PO2
Per
cen
t Sa
tura
tion
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Calculations
• Calculate % saturation- Patient has Hb of 10 gm/dl
- Venous oxygen content is 6.5 ml O2/dl
• Calculate oxygen content- Patient has saturation of 60%- Patient has Hb of 15 gm/dl
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Calculations
• Calculate % saturation- 10 gm/dl * 1.34 ml O2/gm Hb= 13.4 ml O2/dl
- This is max oxygen carrying capacity
- (6.5 ml O2/dl) / (13.4 ml O2/dl) = ~50%
• Calculate oxygen content- 15 gm/dl * 1.34 ml O2/dl = 20 ml O2/dl
- This is max oxygen carrying capacity
- 20 ml O2/dl * 60% saturation = 12 ml O2/dl
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Hemoglobin Dissociation Curve
• Alveoli– Over wide range hemoglobin will be highly saturated
– Example: PO2 of 60, saturation is 89%
• Tissue uptake– Normal: 5 ml O2 /100 ml blood (40 mmHg)
– Exercise: 15 ml O2 /100 ml blood (20 mmHg)
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Increased Blood Flow to Tissue
• Normal blood flow– 20 ml O2/ 100 ml blood * 5000 ml blood/min
1000 ml O2/min
• Increased blood flow– 20 ml O2/ 100 ml blood * 20000 ml blood/min
4000 ml O2/min
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Carbon Monoxide Dissociation Curve
0
20
40
60
80
100
120
0.0 0.4PCO
Per
cen
t S
atu
rati
on
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Transport of Carbon Dioxide from Tissue
CO2H2 CO3 H2O +CO2
H CO3- + H+
H++Hgb- HHgb
Hgb
Hgb. CO2
carbonic anhydrase
H CO3-Cl- CO2
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Carbon Dioxide Dissociation Curve
Venous 52 vol%
Arterial 48 vol%
0
10
20
30
40
50
60
70
80
0 20 40 60 80 100 120PCO2
CO
2 in
blo
od v
olu
mes
%