Women's Health Matters

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How Your Heart Works

Understanding How Your Heart Works

Your heart is a muscle, about the size of a closed fist, which lies to the left of the centre of your chest. Your heart pumps blood, which contains oxygen and nutrients, to all body tissues.

The heart has four chambers. It is divided vertically by a wall, called the septum, into the right and left sides. It is also divided horizontally, with the atria on the top and ventricles on the bottom. The chambers of the heart are separated by valves to prevent the backward flow of blood. The heart has its own blood vessels, called coronary arteries, which run along the outside of the heart muscle. The coronary arteries supply blood to the heart.

How Blood Flows Through the Heart

Oxygen-poor blood returns from the body to the right side of the heart, which pumps the blood to the lungs. In the lungs, the blood picks up oxygen and gets rid of carbon dioxide. The oxygen-rich blood returns to the left side of the heart, which pumps the blood to the rest of the body.

Heart Disease

  • Heart disease and stroke are the leading causes of hospitalization and death in Canada.
  • Thirty-three percent of all female deaths are due to heart attacks and strokes.
  • Cardiovascular disease is a term used to describe diseases of the heart and blood vessels.
  • The main types are coronary heart disease, stroke and diseases of the heart valves and heart muscle.


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  • A publication of:
  • Women's College Hospital