244 
PULMONARY MODELS 
Figure 1. — Diagram showing relations between pul- 
monary and bronchial circulation (after Hayek). See 
Camarri and Marini.^ 
A.p. = Pulmonary artery 
V.p. = Pulmonary vein 
A.Br. = Bronchial artery 
V.Br. = Bronchial vein 
A. pp. = Pleural aborization of the pulmonary artery 
lecting veins. In other species, such as the guinea 
pig, such fibers are found only at the base of 
the veins as they enter the atrium.^ 
The airways are vascularized by the bronchial 
arteries which arise at or just proximal to the 
aortic arch.^ The bronchial artery probably 
does not differ pharmacologically from other 
systemic arteries. In many species this artery 
anastomoses with the pulmonary artery. In 
guinea pigs (and in man and horse), the anas- 
tomoses are profuse and widely disseminated"* 
(Figures 1 and 2) . In other species, such as the 
rat, they are scarce and limited to the hilar re- 
gion.3'* In still other species, such as the cat and 
monkey, they are absent.* These differences in 
circulation make it possible to differentiate be- 
tween airway and alveolar responses by injec- 
tion into either the pulmonary artery or the 
bronchial artery or by the nature of the re- 
sponse to pulmonary artery injection. In cat 
and monkey lungs, it may be possible to dis- 
tinguish not only between alveolar and bron- 
chiolar responses, but simultaneously between 
pulmonary and systemic vascular responses. 
The autonomic responses in the three divi- 
sions also seem to be separate. The pulmonary 
arteries have shown differing reactions to 
acetylcholine resulting from both species dif- 
ferences and differences in experimental tech- 
niques.^ Some experiments have shown vaso- 
*.S. A.O 
Figure 2. — Diagrammatic reconstruction of the pul- 
monary circulation in the lungs of a normal adult. 
See Camarri and Marini.^ 
1 : Precapillary arterio-arteriole 
broncho-pulmonary anastomoses 
2 : Bronchial capillary path 
3: Broncho-pulmonary capillary junction 
4: Pleural vascularization circuit of 
bronchial artery 
5: Broncho-pulmonary venous system of 
Lefort 
6: Hilar junction of broncho-pulmonary 
veins 
7: Sub-pleural circuit of giganto- 
capillaries 
8: Pulmonary capillary path 
9: Pulmonary arterio- venous anastomoses 
A.S. = left atrium 
A.D. = right atrium 
Other abbreviations as in Fig. 1. 
= Arterial blood 
= Venous blood 
= Mixed blood 
