300 



OF THE CIRCULATION OF THE BLOOD. 



the Ventricles, completing the distension of these cavities, and effecting the 

 closure of the Auriculo-veutricular valves which float up into contact. The 



FIG. 120. 



Front view of the movements of the heart in systole and diastole. 



Ventricles instantly contract tightly, closing the Auriculo-ventricular valves, 

 and forcing open the arterial valves, through which the blood is propelled into 



FIG. 121. 



Profile view of the movements of the heart in systole and diastole. 



the arteries. The great arteries, now distended with blood, recoil on their con- 

 tents and close the setmlunar valves. As soon as the contraction of the Veu- 



