Summary of Blood Flow through the Heart:

1.

Blood enters the heart through two large veins, the superior and inferior vena cava, emptying deoxygenated blood from the body into the right atrium. (Venous blood from the heart itself also dumps into the right atrium via the coronary sinus.)

2.

Blood flows from the right atrium into the right ventricle through the tricuspid valve.

3.

From the right ventricle, it is pumped through the pulmonary valve into the pulmonary trunk which splits into right and left pulmonary arteries that travel to the lungs.

4.

Once blood is oxygenated, it flows back to the heart through the right and left pulmonary veins and into the left atrium. (There are two pairs of pulmonary veins: the right and left pairs which total four in all. All four empty into the left atrium.) Blood flows from the left atrium through the mitral valve (a.k.a. bicuspid) into the left ventricle.

5.

The blood is then pumped by the strong left ventricle through the aortic valve and into the aorta. From there, it carries blood to the entire body!