1. The walls of ventricles are much thicker than atria because, ventricles have to exert more pressure as it pumps out blood to all organs of the body. Atria receives blood so they have less load to take, hence thinner walls.

2. Right ventricle receives oxygenated blood from the lungs than pumps this blood to the left ventricle.

3.In turn left ventricle pumps oxygenated blood to all parts of the body.