How your heart works

The heart distributes the nutrients, minerals, and oxygen your body needs to function properly.


Your heart is a muscle that pumps blood throughout your body. Every time your heart beats, it is pumping blood. To do its work, your heart needs a constant supply of oxygen-rich blood, which it obtains from the lungs. The heart pumps the oxygen-rich blood to provide the nutrients, minerals and oxygen needed for your body to function properly.


The heart muscle is divided into four compartments or chambers, with two on the left side and two on the right side. The upper chamber on each side is called an atrium. The atrium receives and collects blood. The lower chamber on each side is called a ventricle. The ventricle pumps blood. The right ventricle pumps blood only to the lungs. The left ventricle is the main pumping chamber of the heart. It pumps blood to all parts of the body except the lungs.


There are four valves that control the flow of blood inside the heart. They are like one-way doors to keep the blood moving in one direction. When the heart beats, the valves close to keep the blood from flowing backward.

Chambers and valves work together

Oxygen-poor blood that returns from the body collects in the right side of the heart (right atrium). It passes through the tricuspid valve into the right ventricle, which pumps it through the pulmonic valve into the lungs, where it picks up fresh oxygen.

Oxygen-rich blood coming from the lungs flows into the left side of the heart, where it passes through the mitral valve into the left ventricle. It is then pumped through the aortic valve into the aorta (main artery) and all the other arteries. The aorta is the largest artery in the body.

Electrical System

The heart’s electrical system provides the power to keep your heart pumping. Electrical impulses travel first through the walls of the atrium, starting in an area known as the heart’s natural pacemaker, and continue through the ventricles. The impulses trigger timed contractions, which coordinate the flow of blood between the four chambers.

If the heart’s electrical system gets out of sync, cardiac arrhythmia can occur. An electrophysiology procedure can help diagnose a bad electrical pathway in the heart. Some arrhythmia conditions can be treated with cardiac ablation, which stops the bad electrical pathway. Other treatment options may include a pacemaker or a defibrillator implant.

Coronary arteries

Coronary arteries are the blood vessels that wrap around the heart muscle and keep it supplied with oxygen-rich blood. When blood is pumped by the left ventricle, it is forced into the body’s main artery, the aorta, located at the top of the heart. Two coronary arteries, the left main artery and the right coronary artery, branch off the aorta.

The left main artery is about as wide as a drinking straw and less than an inch long. It branches into two narrower arteries: the left anterior descending, which travels down the front side of the heart; and the left circumflex, which circles around the left side and then to the back of the heart.

The right coronary artery branches from the aorta, circles around the right side and then to the back of the heart. These arteries are on the outside surface of the heart. They divide into smaller branches, similar to a tree, and lead deep into the heart muscle to carry the oxygen-rich blood to the cells.

Understanding How Your Heart Works

Diagnosing your condition

Diagnostic tests such as EKGs, stress tests, nuclear studies and/or coronary angiography (cardiac catheterization) can help your doctor identify the heart condition you have: coronary artery disease, heart valve disease or heart muscle disease.

By obtaining this information, your doctor can determine the best treatment plan and course of action for your particular situation. This can include:
  • Diet and exercise
  • Medication
  • Coronary angioplasty
  • Coronary atherectomy
  • Coronary stent
  • Pacemaker
  • Bypass surgery
  • Heart valve surgery

What can I do?

You should change any unhealthy habits (also called risk factors) that helped to create your heart problems in the first place. Some risk factors are smoking, eating too much fat or salt, and not getting enough exercise. Making changes to reduce risk factors can prevent further damage and may even improve the health of your heart.

Heart Care at PeaceHealth Southwest

Your heart is the hardest working muscle in your body. PeaceHealth Southwest's Heart & Vascular Center strives to keep it that way. Whatever your heart problem may be, you’re in good hands with the technology, treatment, and restorative care at PeaceHealth Southwest.


It is important to be your own best health advocate. A good way to do that is by committing to routine physical exams and diagnostic tests as often as is recommended by your cardiac specialist. Early detection of heart disease is the key to effective treatment