The heart
Classified in Biology
Written at on 
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The heart is a hollow organ,located in the chest cavity,between the lungs.It is covered by a membrane called the pericardium,and its walls are made of cardic or heart muscle myocardium,which contracts and relaxes rhythmically.The heart has two halves,separated by the cardic septum,.Each half of the heart has two chambers,an atrium.Each atrium is connected only to its corresponding ventricle.The mitral and tricuspid valves allo blood to flow from the atria to their corresponding ventricles and prevent blood from flowing in the opposite direction.