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How does blood
flow through the heart?
The right and left
sides of the heart work together.
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Right
Side
|
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Left
Side
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| Blood
enters the heart through two large veins, the inferior and superior
vena cava, emptying oxygen-poor blood from the body into the right
atrium. |
 |
The
pulmonary vein empties oxygen-rich blood, from the lungs into the
left atrium. |
|
Atrial contraction:
blood flows from your right atrium into your right ventricle through
the open tricuspid valve.
When the ventricles
are full, the tricuspid valve shuts. This prevents blood from flowing
backward into the atria while the ventricles contract (squeeze).
|
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Atrial contraction:
blood flows from your left atrium into your left ventricle through
the open mitral valve.
When the ventricles
are full, the mitral valve shuts. This prevents blood from flowing
backward into the atria while the ventricles contract (squeeze).
|
| Ventricular
contraction: blood leaves the heart through the pulmonic valve,
into the pulmonary artery and to the lungs. |
 |
Ventricular
contraction: blood leaves the heart through the aortic valve,
into the aorta and to the body. |
|
This
pattern is repeated over and over, causing blood to flow continuously
to the heart, lungs and body.
|
How
does blood flow through your lungs?
 |
| Oxygen
and carbon dioxide travels to and from tiny air sacs in the
lungs, through the walls of the capillaries, into the blood. |
Once blood travels
through the pulmonic valve, it enters your lungs. This is called
the pulmonary circulation. From your pulmonic valve, blood travels
to the pulmonary artery to tiny capillary vessels in the lungs.
Here, oxygen travels from the tiny air sacs in the lungs, through
the walls of the capillaries, into the blood. At the same time,
carbon dioxide, a waste product of metabolism, passes from the blood
into the air sacs. Carbon dioxide leaves the body when you exhale.
Once the blood is purified and oxygenated, it travels back to the
left atrium through the pulmonary veins.
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© Cleveland Clinic
Foundation, Reviewed 1/02
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