What is the structure of human heart??

Explanation:

The human heart is a four-chambered muscular organ, shaped and sized roughly like a man's closed fist with two-thirds of the mass to the left of midline.

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There are four chambers in the human heart. The right and left atrium are the upper two chambers. The right and left ventricles are the lower two chambers. The pulmonary vein transports oxygenated blood from the lungs to the left atrium. The pulmonary arteries carry blood from the right side of the heart to the lungs. A pericardial sac surrounds the heart and is lined by the parietal layers of a serous membrane.

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