Answer:
The atria only receives blood and the ventricles have to pump the blood to the lungs or the rest of the body.
Step-by-step explanation:
Our heart is divided into 4 chambers, two relatively small upper chambers called atria and two larger lower chambers called ventricles. The walls of the ventricles are much thicker than that of the atria and is necessary because ventricles have to pump the blood to lungs and all the body parts. The right and the left atria are separated by a thin, muscular wall called the interatrial septum whereas the right and left ventricles are separated by thick walled interventricular septum.