The rectum of the human body is the end portion of the large intestine that transporst waste to the anus. The hemorrhoidal plexus is the protective coating around the rectum. The hemorrhoidal plexus also contains the beginning of the middle rectal veins. The veins also receive contributions from the prostate and bladder. The veins move laterally across the pelvis, ending at the internal iliac vein. The internal iliac vein contributes to the area around the base of the spine and the pelvis. The veins located in the rectum and colon that are above the rectal veins drain into the hepatic portal, which sends blood to the liver. The middle rectal veins are considered inferior veins and are part of the systemic circulation system. Blood that is low in oxygen is pushed out of the rectum and colon and pushed up to the heart. The system bypasses processing through the liver. The heart oxygenates the blood and sends it back into the body.