Chapter 22
The Respiratory System
833
22
Red blood cell
Blood plasma
Blood plasma
Slow
Tissue cell
Interstitial fluid
Alveolus
Fused basement membranes
Carbonic
anhydrase
CO
2
CO
2
CO
2
CO
2
CO
2
CO
2
CO
2
(a) Oxygen release and carbon dioxide pickup at the tissues
(b) Oxygen pickup and carbon dioxide release in the lungs
CO
2
CO
2
(dissolved in plasma)
CO
2
CO
2
+
H
2
O
H
2
CO
3
HCO
3
-
+
H
+
Fast
CO
2
CO
2
+
H
2
O
H
2
CO
3
CO
2
O
2
O
2
O
2
O
2
O
2
(dissolved in plasma)
O
2
(dissolved in plasma)
CO
2
+
Hb
HbCO
2
HbO
2
O
2
+
Hb
(Carbamino-
hemoglobin)
HCO
3
-
+
H
+
HCO
3
-
Cl
-
Cl
-
Cl
-
HHb
Binds to
plasma
proteins
Chloride
shift
(in) via
transport
protein
Slow
CO
2
(dissolved in plasma)
CO
2
+
H
2
O
H
2
CO
3
HCO
3
-
+
H
+
Red blood cell
Carbonic
anhydrase
Fast
CO
2
+
H
2
O
H
2
CO
3
CO
2
+
Hb
HbCO
2
O
2
+
HHb
HbO
2
+
H
+
(Carbamino-
hemoglobin)
HCO
3
-
+
H
+
HCO
3
-
Cl
-
Chloride
shift
(out) via
transport
protein
Figure 22.22
Transport and exchange of CO
2
and O
2
.
Relative sizes of the transport
arrows indicate the proportionate amounts of O
2
and CO
2
moved by each method. (H
2
CO
3
5
carbonic acid, HCO
3
2
5
bicarbonate, HHb
5
reduced hemoglobin, HbO
2
5
oxyhemoglobin.)
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