Vein veins), not their oxygen content. In addition, deoxygenated blood that is carried from the tissues back to the heart for reoxygenation in the systemic circulation still carries some oxygen, though it is considerably less than that carried by the systemic arteries or pulmonary veins. Although most veins take blood back to the heart, there is an exception. Portal veins carry blood between capillary beds. For example, the hepatic portal vein takes blood from the capillary beds in the digestive tract and transports it to the capillary beds in the liver. The blood is then drained in the gastrointestinal tract and
Renal vein directly into the IVC. Often, each renal vein will have a branch that receives blood from the ureter. It is usually singular to each kidney, except in the condition "multiple renal veins". In some people the left renal vein passes behind the abdominal aorta instead of in front of it, this is termed a retroaortic left renal vein, which is also known as "The Vein of Schnitker." If there is both a vein passing in front of and one behind the aorta this is called a circumaortic renal vein. Diseases associated with the renal vein include renal vein thrombosis (RVT)