Page 136 - Color_Atlas_of_Physiology_5th_Ed._-_A._Despopoulos_2003

A. Regional blood flow in the lung (upright chest position)

Alveolus Zone 1

Pulmonary Pulmonary Level of lung PA > Pprecap > Ppostcap
artery vein Zone 2
Pprecap > PA > Ppostcap .
.
Lung Zone 3
Pprecap > Ppostcap > PA Pulmonary Blood Flow, VA–Q Ratio

Perfusion Q
Pprecap PA Ppostcap
· ·
B. Regional perfusion and C. Effect of ventilation-perfusion ratio (VA/Q)
ventilation of lung on partial pressures in lung
Pressures in kPa Ambient air: P O 2 = 20, P CO 2 = 0

VA/Q
0 3

Apex VA = 0 VA VA Plate 5.9
2 VA
Q P O 2 = 5.33 P O 2 =13.33 P O 2 = 20
Rib number Ventilation VA P CO 2 = 6.13 P CO 2 = 5.33 P CO 2 = 0

Perfusion Q
5 Q 5.6 Q Q = 0
Base VA = 0 VA = ≈1 VA ∞

0 0.5 1.0 1.5 Q Q 6 Q
1 2 3
Q and VA (L/min per L lung) Not ventilated Normal Not perfused
D. Regional parameters of lung function
Ambient air
0.07 0.24 0.07 3.3 17.6 3.7
0.93 13.3 5.3

0.13 0.82 1.29 0.63 11.9 5.6
Mixed
venous blood
8 (L/min) (kPa)
6
P CO 2 (kPa) 4 2 Fraction of lung volume

0 · · VA/Q PA O 2 PA CO 2
6 8 10 12 14 16 18 20 · A V · Q
P O 2 (kPa) End-capillaries 123
(A, B, C, D after West et al.)
Despopoulos, Color Atlas of Physiology © 2003 Thieme
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