268 



PHYSIOLOGY 



CHAP. 



to the inferior vena cava is provided the greater part of the 

 arterial blood brought by the inferior vena cava passes from the 

 right to the left auricle through the foramen ovale, and the 

 greater part of the venous blood brought by the superior vena 

 cava flows from the right auricle into the right ventricle. When, 



2 ... 



FIG. 119. Foetal liver with its vessels. From Kollmann's Embryology. (Seen from the lower 

 posterior surface.) 1, hepatic vein ; 2, ductus venosus Arantii ; 3, umbilical vein ; 4, portal 

 vein ; 5, gall bladder ; 6, hepatic vein ; 7, inferior vena cava. 



therefore, the heart is emptied during systole, the right ventricle 

 forces through the pulmonary artery blood which is almost entirely 

 venous, and the left ventricle forces through the aorta blood 

 which is chiefly arterial. 



Only a small part of the blood conveyed by the pulmonary 

 artery passes through the four pulmonary veins into the left 



