How do you account for the following differences?

(a) The left ventricle has thicker walls than the right ventricle.

(b) The walls of the right ventricle are thicker than those of the right auricle.

(a) The left ventricle has thicker walls than the right ventricle because they have to pump blood to long distances. The right ventricle pumps blood only up to the lungs for oxygenation. But the left ventricle pumps it up to the farthest points in the body such as up to the toes in the feet or up to the brain against gravity. Therefore its walls are thicker.

(b) The walls of right ventricle are thicker than those of the right auricle because they have to pump blood to the lungs through pulmonary artery.