THE HEART 



305 



It is clear, therefore, that the abdominal viscera (with the 

 exception of the liver) and the lower limbs will not be so well 

 nourished at birth as the upper portion of the body. 



The hypogastric arteries, which arise from the common 



Superior_ 

 vena cava 



Ductus venosus 



Portal vein ; 



Umbilical vein 



- Arch of aorta 

 Ductus arteriosus 



V 1 Pulmonary artery 



Hypogastric arteries 

 FIG. no. Diagram to illustrate the Foetal Circulation. 



The course of the pure blood is indicated by the plain arrows ; the dotted arrows 

 indicate the course of the impure or mixed blood. 



iliacs, pass up the anterior abdominal wall and enter the 

 umbilical cord. They convey impure blood to the placenta 

 from which it is returned, after being purified, by the umbilica 

 vein. It may be noted that the umbilical cord contains two 

 arteries but only one vein. 



Several important changes occur at birth. The expansion 

 20 



