Why are the human heart chambers not the same size?

Answer 1

The two lower chambers of the heart are larger than the two upper chambers because they must generate the pumping force to move blood through the circulatory system. The left ventricle is larger than the right, reflecting the longer length of the systemic circuit.

Answer 2

The reason in very simple. Upper chambers have to pump the blood in lower chambers. This does nor require much force. So the upper chambers are smaller and have got thin wall. The lower chambers has to pump blood in the system. This requires much more power. So the lower chambers are larger and thicker.

Answer 3

Nothing is perfect, so the human heart chambers are different sizes because of the different amounts of blood they have at a time.