Biology help - Atria and Ventricles!?

The left ventricle is thicker than the right ventricle. This is because the left ventricle has to pump the blood to the entire body. The right ventricle only pumps blood through the pulmonary circulation (the lungs). The left ventricle is thicker so that the extra pressure needed to pump the blood throughout the body is created. The right ventricle works at a lower pressure (32/8 mm of mercury) while the left ventricle works at 120/80 mm of mercury normally.