The circulatory system is fairly simple. The system consists of the heart, veins, arteries and capillaries. Sea turtles unlike humans have a three chambered heart. The heart consists of the left auricle, the right auricle and the ventricle. The ventricle is somewhat separated by a partial septum which helps to minimize the mixing of deoxygenated and oxygenated blood. Deoxygenated blood flows into the right auricle. The auricle contracts and forces the deoxygenated blood into the ventricle. The ventricle forces the blood into the lungs where carbon dioxide is extracted and oxygen is added. The blood, which is now oxygenated then enters the left auricle. The left auricle then contracts forcing the blood once again into the ventricle. The ventricle then sends oxygenated blood is carried away from the heart via arteries. As the arteries stretch throughout the sea turtles body they become narrower until they become tiny blood vessels named capillaries.