PORTAL CIRCULATION 2OQ 



close to the spinal column, to pass through the diaphragm and 

 enter the pericardium and right atrium of the heart. 



From the abdominal walls the phrenic and lumbar veins open 

 into the inferior vena cava. 



From abdominal viscera the renal and adrenal veins open into 

 the inferior vena cava. 



The right ovarian and right spermatic veins open into the in- 

 ferior vena cava; the left ovarian and left spermatic veins open into 

 the left renal vein which carries their blood to the inferior vena 

 cava. 



The splenic (or lienal), gastric, and mesenteric veins form the 

 portal vein, which is four inches long and enters the liver at the 

 transverse fissure or porta (Figs. 112, 146). 



THE PORTAL CIRCULATION 



This is the circulation of venous blood through the liver. The 

 portal vein bears the products of digestion from stomach and 

 intestines; entering the liver at the porta or gate, it divides into 

 branches which form an extensive network in its substance. 



Having been distributed through these fine capillaries, the 

 blood leaves the liver by the hepatic veins, which open directly 

 into the inferior vena cava. 



Vessels passing through the porta (or 

 transverse fissure) of the liver: 



Entering 



Hepatic artery. 



Portal vein. 



Two hepatic ducts. 



Lymphatics. 



All of the hepatic veins leave the liver at the back, opening at once into 

 a larger vein running to the heart (the inferior vena cava). The great 

 quantity of venous blood which the liver contains gives to it its dark color. 



SUMMARY 



The venous blood from all structures below the diaphragm 

 (except upper lumbar walls) is returned through the Inferior 

 Vena Cava to the heart (right atrium). 



THE FETAL CIRCULATION 



The fetus is nourished by blood brought from the uterine 

 (placental) arteries of the mother, through a special vessel called 

 14 



