How the Heart Works: The Heart House

To simplify how blood flows through a normal, healthy heart
think of the heart as a house with:

The heart has 2 small back rooms:

The Right Atrium is the room to the right. The Left Atrium is the room to the left.

The heart has 2 large front rooms:

The Right Ventricle is the room to the right. The Left Ventricle is the room to the left.

All of the hearts' 4 doors only open one way:

The Tricuspid Valve is the door between the Right Atrium and the Right Ventricle.

The Pulmonic Valve is the door between the Right Ventricle and the Pulmonary Artery.

The Mitral Valve is the door between the Left Atrium and the Left Ventricle.

The Aortic Valve is the door between the Left Ventricle and the Aorta.

There are 2 big and 4 small entering hallways:

The Superior Venacava is the big hallway (vessel) that brings blood back from the head and top part of the body.

The Inferior Venacava is the big hallway (vessel) that brings blood back from the lower part of the body.

The 4 Pulmonary Veins are the smaller hallways that collect blood from the lungs and sends it to the left atrium.

There are 2 big exiting hallways:

The Aorta sends blood to the whole body.

The Pulmonary Artery sends blood to the lungs.

The Plumbing (Coronary Arteries)
As in your house the heart house also needs plumbing. The plumbing in the heart house delivers fresh blood from the aorta to supply the walls of the heart with blood. Remember the walls of the heart are very important muscles which squeeze and relax so the heart can push the blood out. The walls of the heart are made of muscle. When the walls squeeze (contract) they push the blood out to the body. When the walls relax they allow the heart to fill with blood again. This cycle happens about 70 times per minute and so to do this kind of work the muscle of the heart needs to get enough blood.

The arteries which supply the walls of the heart with blood are called Coronary Arteries. Those arteries are very important because they bring fresh blood to the walls of the heart which needs lots of oxygen. Should any of these arteries be obstructed the blood will not flow to the muscle of the heart and this condition is what we call a heart attack. Heart Attacks happen when there is no blood going to supply the muscles of the heart.