Who first described correctly the flow of blood in body?

The flow of blood in the human body was first correctly described by a Persian physician named Ibn al-Nafis (1210-1288) in his book "Sharh al-Qanun fi al-Tibb" (Commentary on the Canon of Avicenna). Ibn al-Nafis was born in Damascus and studied medicine in Cairo, where he served as the director of the Nasser Hospital. In his book, Ibn al-Nafis criticized the prevailing Galenic theory, which held that blood flowed from the liver to the rest of the body through the veins and then returned to the heart. Ibn al-Nafis proposed that blood flowed from the right ventricle of the heart through the pulmonary artery to the lungs, where it was oxygenated, and then returned to the left atrium of the heart through the pulmonary vein. He also described the presence of valves in the heart, which prevented blood from flowing backward.