142 



PRACTICAL PHYSIOLOGY 



and the respiratory oscillations of arterial pressure. The pulsations 

 are distorted by the momentum of the mercury. 



The inspiratory fall of intra- thoracic pressure aspirates blood into 

 the intra-thoracic veins and thin walled auricles, and dilates the 



FIG. 139. Mercurial manometer fitted with float and writing style. 



pulmonary vessels. The descent of the diaphragm expresses blood 

 from the liver and abdominal vessels into the right heart in the living 

 animal. Thoracic and abdominal breathing have a contrary effect. 

 Thoracic breathing produces an inspiratory fall of arterial pressure, arid 

 abdominal an inspiratory rise. 



