The heart receives deoxygenated blood from the body in the right auricle, which passes to the right ventricle and is then pumped to the lungs. Oxygenated blood returns from the lungs to the left auricle and left ventricle. The ventricles then contract sending blood to the body and lungs, with valves preventing backflow. The diagram labels the major blood vessels and chambers of the heart.

1. The heart receives blood from the body (blue) in the right auricle (14), which allows the blood to pass into the right ventricle (10) from which it is
pumped to the lungs. The blood comes back charged with oxygen (red) to the left auricle (7). The movement of blood through the lungs is called
the pulmonary circulation. The heart depicted above is relaxed and filling with blood. In a moment it will contract and the ventricles (9 and 10)
will force blood out to the body and the lungs. To keep blood from entering the auricles, muscle extensions attached with cords to the cuspid
valves (8 and 12) will hold them closed. Some valve parts have been cut away to give an interior view of the heart.
1. Aorta
2. Innominate artery 3.Left common carotid artery 4.Left subclavian artery 5.Pulmonary artery
7.Left auricle 8.Bicuspid valve
9.Left ventricle
10.Right ventricle
11.Papillary muscle
13.Inferior vena cava 14.Right auricle 15.Superior vena cava.
6.Pulmonary vein
12.Tricuspid valve