The spleen provides a critical function to the body. It not only recycles iron, but it also stores, recycles, and produces red blood cells. The spleen's white pulp processes antibodies and helps remove bacteria from the blood. As such, the spleen's role is not only active in the circulatory system, but in the body's immune system as well.
Formerly the lienal vein, the splenic vein services the spleen. It drains deoxygenated blood away from the spleen to a junction with the superior mesenteric vein. As a result, the hepatic portal vein is formed. From there, deoxygenated blood ultimately travels to the inferior vena cava and to the heart, which pumps it into the lung's blood vessels where it is supplied with fresh oxygen.
The splenic vein works in opposition to the splenic artery, which branches off the celiac artery. The splenic artery feeds oxygenated blood to the spleen and the surrounding areas, and the course of the splenic vein runs close to the artery. Since the spleen is vital to the circulatory system, it needs constant functionality from both blood vessels.