The Venous System:

The function of pulmonary veins:

The veins from the lungs, called pulmonary veins return the oxygenated blood to the left atrium of the heart.

The function of superior vena cava and the inferior vena cava:

Two major veins i.e. the superior vena cava and the inferior vena cava, carrying the deoxygenated blood from the rest of the body, empty into the right atrium. The superior vena cava forms when different veins from the head, shoulders, and arms join together. From the legs, the deoxygenated blood is returned to the heart by many veins which empty into the inferior vena cava.

The function of femoral vein:

Veins carrying blood from the calf, foot, and knee join together to form the femoral vein It empties into the external iliac vein which joins with the internal iliac, and both empty into the common iliac vein. The right and left common iliac veins to join to form the inferior vena cava. Many short veins empty into the inferior vena cava, among these are the hepatic, renal veins, and gonadal veins.

The function of the hepatic portal vein:

All the veins coming from the stomach, spleen, pancreas, and intestine drain into the hepatic portal vein, which carries the blood to the liver. From the liver, a hepatic vein carries blood and empties into the inferior vena cava, Function of renal veins: The two renal veins carry blood from the kidneys while the two gonadal veins carry blood from gonads to the inferior vena cava. In the thoracic cavity, the inferior vena cava also receives veins from thoracic walls and ribs.