The main work of heart is to pump blood throughout the body.its in muscular organ which helps in the pumping of blood. in mammals it is divided into four parts i.e-1)two upper chambers... !left auricle or atrium !right auricle or atrium
2)two lower chambers.....!left ventricle ! right ventricle
the right atrium or auricle receives the deoxygenated blood through the veins.then it is pumped to right ventricle from there the pulmonary arteries carry the blood to lungs for its purification. when the blood gets purified then the oxygenated blood is carries to left auricle to pulmonary veins(only veins in body which carry oxygenated blood else in the body veins carry deoxygentaed blood).from left auricle its pumped into left ventricle.....from there the blood is pumped throughout the body.