Indentify the structure of the heart

The left superior pulmonary vein returns blood from the upper left lobe of the lung back to the left atrium. the lower left-hand chamber of the heart that receives blood from the left atrium and propels the blood into the aorta. The left ventricle has a much thicker wall than the right ventricle.

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 mid line. The heart is enclosed in a pericardial sac that is lined with the parietal layers of a serous membrane.