Table of Contents
The Left Side of the Heart. The left system receives blood from the lungs. This blood is now rich in oxygen.
- The oxygen-rich blood returns through veins coming from the lungs (pulmonary veins) to the heart.
- The heart receives the oxygen-rich blood from the lungs in the left atrium, the first chamber on the left side.
- Here, it moves to the left ventricle, a powerful muscular chamber that pumps the blood back out to the body.
- The left ventricle is the strongest of the heart's pumps. Its thicker muscles need to perform contractions powerful enough to force the blood to all parts of the body.
- This strong contraction produces systolic blood pressure (the first and higher number in blood pressure measurement). The lower number (diastolic blood pressure) is measured when the left ventricle relaxes to refill with blood between beats.
- Blood leaves the heart through the aorta, the major artery that feeds blood to the entire body.
The Valves. Valves are muscular flaps that open and close so blood will flow in the right direction. There are four valves in the heart:
- The tricuspid regulates blood flow between the right atrium and the right ventricle.
- The pulmonary valve opens to allow blood to flow from the right ventricle to the lungs.
- The mitral valve regulates blood flow between the left atrium and the left ventricle.
- The aortic valve allows blood to flow from the left ventricle to the aorta.
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Click the icon to see an image of the internal structures of the heart. |
The Heart's Electrical System. The heartbeats are triggered and regulated by the conducting system, a network of specialized muscle cells that form an independent electrical system in the heart muscles. These cells are connected by channels that pass chemically-triggered electrical impulses.
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Click the icon to see an image of the conduction system of the heart. |
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Review Date: 05/04/2011
Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical
School; Physician, Massachusetts General Hospital. Also reviewed by
David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)
