The tissues receive nourishment and eliminate waste products through their thin walls. The Circulation of the Blood. The blood is constantly circulating throughout the body. There are two systems which take care of the circulation. Circulation from the heart to the lungs and back to the heart.
Blood is pumped by the heart to the lungs to be purified.
With each respiration an exchange of gas takes place. Circulation from the heart to the entire body and then back to the heart. Course of Blood Flow. From the right atrium, the venous blood passes through a valve into the right ventricle. From the right ventricle, the venous blood is carried through the pulmonary artery up to the lungs to be oxygenated or purified.