Ibn al-Nafis Describes Pulmonary Circulation

Ala al-Din Ibn al-Nafis described the flow of blood through the lungs in his commentary on Ibn Sina's Canon, written in Cairo around 1242. He argued that blood passes from the right side of the heart to the left through the lungs. He also rejected the older idea that blood moved through tiny pores in the heart wall. His account came several centuries before similar descriptions in Europe.