Your heart is only able to beat because it produces electricity that travels through your heart muscle. Normally, these electrical signals come from an area in your heart called the SA node or the main pacemaker. This is the SA node at work. In a normal situation, the electrical signals cause the upper parts of the heart to beat together. This pushes blood into the lower parts of the heart. Then, as the electrical signals continue through the heart, the lower chambers contract to push the blood out of the heart. Notice how this is a smooth process that results in heartbeats that happen at a controlled or regular rate and rhythm.