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How Your Heart Works

By:Carl Bianco, M.D.|

Chambers and Valves

Figure 2
HowStuffWorks.com

The heart is divided into four chambers: (see Figure 2)

  1. right atrium (RA)
  2. right ventricle (RV)
  3. left atrium (LA)
  4. left ventricle (LV)

Each chamber has a sort of one-way valve at its exit that preventsbloodfrom flowing backwards. When each chamber contracts, the valve at its exit opens. When it is finished contracting, the valve closes so that blood does not flow backwards.

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  1. The tricuspid valveis at the exit of the right atrium.
  2. The pulmonary valveis at the exit of the right ventricle.
  3. The mitral valve在左心房的退出。
  4. The aortic valveis at the exit of the left ventricle.

When the heartmusclecontracts or beats (calledsystole), it pumps blood out of the heart. The heart contracts in two stages. In the first stage, the right and left atria contract at the same time, pumping blood to the right and left ventricles. Then the ventricles contract together to propel blood out of the heart. Then the heart muscle relaxes (calleddiastole) before the next heartbeat. This allows blood to fill up the heart again.

The right and left sides of the heart have separate functions. The right side of the heart collects oxygen-poor blood from the body and pumps it to thelungswhere it picks up oxygen and releases carbon dioxide. The left side of the heart then collects oxygen-rich blood from the lungs and pumps it to the body so that thecellsthroughout your body have the oxygen they need to function properly.