Ventricles are thick walled as compared to auricles because
It has to pump the blood with more force
The human heart has four separate chambers. Atria are the upper chambers of the heart and ventricles are the lower chambers. There are one atrium and one ventricle on the right side of the heart and one of each on the left side. Both atria and ventricles have valves that assist in the pumping of blood. The ventricles have much thicker walls than the atria since they need to pump the blood much further and with more force.