The heart is a muscular organ and has four different chambers( atria and ventricles)Firstly oxygen rich blood from the lungs comes to the upper left chamber, left atrium,a thin walled chamber,the left atrium relaxes while collecting the blood. Then, it contracts while the left ventricle expands and the blood is transferred to it. The blood is then pumped out to the body. De-oxygenated blood comes from the body to the upper right chamber, the right atrium, as it expands. As it contracts, the right ventricle dilates and the blood is transferred to the right ventricle ,which pumps the blood to the lungs for oxygenation. And the cycle continues~it\’s long?
Human heart has four main parts right and left auricle and left and right ventricle.impure blood from diff parts of body brought to left auricle by upper vena cava ,from left auricle impure blood goes to lung by pulmonary artery for purification .the pure blood from lungs to right auricle and then to right ventricle .from right ventricle it is supplied to all parts of body.