Diagram of Human Heart and Blood Circulation in It The shape of the human heart is like an upside-down pear, weighing between 7-15 ounces, and is little larger than the size of the fist. It is located between the lungs, in the middle of the chest, behind and slightly to the left of the breast bone. The heart, one of the most significant organs in the human body, is a muscular pump, which pumps ...