At the end of the arterioles are, guess what, capillaries. The blood gives up its cargo as it passes through the capillaries and enters the venous system. The venous system carries the blood back to the heart. The superior vena cava carries the blood from the upper part of the body to the heart. The inferior vena cava carries the blood from the lower body to the heart.
Venous blood is really dark red or maroon in color.
Veins do have a bluish appearance and this may be why people think venous blood is blue. Both the superior and inferior vena cava end in the right atrium. The superior vena cava enters from the top and the inferior vena cava enters from the bottom. This completes our little journey through the circulatory system. I hope the blood has continued to flow to your brain as you read this and you managed to stay awake.