João Rodrigues de Castelo Branco, better known as Amato Lusitano and Amatus Lusitanus (1511–1568), was a notable Portuguese Jewish physician of the 16th century. Like Herophilus, Galen, Ibn al-Nafis, Michael Servetus, Realdo Colombo and William Harvey, he is credited as making a discovery in the circulation of the blood. He is said to have discovered the function of the valves in the circulation of the blood.

William Harvey was an English physician who made influential contributions in anatomy and physiology. He was the first known physician to describe completely, and in detail, the systemic circulation and properties of blood being pumped to the brain and the rest of the body by the heart, though earlier writers, such as Realdo Colombo, Michael Servetus, and Jacques Dubois, had provided precursors of the theory.