A Portuguese doctor Amato Lusitano was the first to describe the Physiology of Circulation. The Systemic Circulation is a part of the Cardiovascular system. It carries the oxygenated blood away from the heart and the deoxygenated blood brings back to the heart. Dr. Amato Lusitano was first to describe the venous valves.
The term Pulmonary Circulation was first proposed by the Ibn al-Nafis.