In mammals the heart produces two separate circulations, the pulmonary to the lungs and systemic to the rest of the body. These two separate circulations are jointly called double circulation. From the right ventricle deoxygenated blood goes to lung for purification and comes back to left auricle through pulmonary vein after purification which is known as pulmonary circulation.
Distribution of blood from left ventricle to different parts of the body and back to hearts as deoxygenated blood is known as systemic circulation.
