482 THE RESPIRATORY MECHANISM. 



tractile effects of the adrenal secretion on the myocardium are 

 reproduced in the pulmonary lobules, the abundant elastic filters 

 of the latter acting as contractile elements. 



6. The respiratory interchanges that occur in the lobules rep- 

 resent the end-result of a process which includes: 



(a) The production of the adrenal secretion, which provides 

 the blood with its affinity for oxygen. 



(b) The admixture of granules f$ to the venous blood of 

 the inferior vena cava, to insure, with the arterial blood of the 

 coronaries, the oxidation processes through which the right heart 

 acquires its mechanical energy. 



(c) The motor functions of the right heart. 



(d) The vasomotor functions of the pulmonary artery and 

 its ramifications. 



(e) The admixture of the arterial blood of the bronchial ter- 

 minal artery to the venous blood of the pulmonary capillaries as 

 these reach the lobule. 



(f) The oxidation of the granules ft in the pulmonary cap- 

 illaries by the oxidizing substance in the blood derived from the 

 bronchial vessels. 



(g) Conversion of the venous blood, as it courses through the 

 lobular capillaries, into arterial blood. 



