How does the heart pump blood through the body?

To pump blood through the heart and then the rest of the body:

• An impulse starts in the SA or sinoatrial node, located in the right top chamber or right atrium. This impulse causes the right and left atria to contract.

• The contraction pushes blood from the atria into the heart’s lower chambers, or ventricles.

• Another impulse moves into the AV or atrioventricular node, the electrical connection between the atria and ventricles. This causes another contraction.

• This contraction causes the ventricles to push blood from the heart into the lungs and the rest of the body.

• The veins in the lungs, called pulmonary veins, send oxygen-rich blood from the lungs back into left atrium to repeat the cycle.

To pump blood throughout your body, your heart contracts (squeezes) and relaxes in a rhythm. A natural "pacemaker," the sinoatrial (SA) node, sits at the top of the right atrium and controls this rhythm by sending out a series of electrical impulses. The impulses travel from the SA node and down an electrical pathway along the heart muscle walls, causing the heart to contract. The muscular heart wall is called the myocardium. The myocardium serves as a strong pump to move blood through your blood vessels.