William Harvey 1628 – The First Person to Describe Blood Circulation Correctly

Science correspondent Robert Adler: “Today, the basics of how blood circulates through the body seem trivial. Elementary schoolchildren learn that the heart pumps oxygen-rich blood through arteries to the body, veins return blood containing carbon dioxide to the heart, and tiny capillaries connect arteries and veins. Yet the workings of the heart and blood vessels remained a profound mystery from antiquity until the first quarter of the seventeenth century."

English physician William Harvey was the first to describe blood circulation in the body correctly and in detail. In his 1628 work De Motu Cordis(On the Motion of the Heart and Blood in Animals), Harvey traced the correct path of blood through studies in living animals, in which he could pinch (or cut) various blood vessels near the heart and note the directions of flow. He also applied pressure to vessels near the skin of human subjects and recorded the direction of blood flow by observing swelling along with congested or pale areas of the arms. In contrast to physicians who speculated that the liver produced blood continuously absorbed by the body, Harvey showed that blood was recycled. He also recognized that valves in veins, discovered by his teacher Hieronymus Fabricius, facilitated one-way blood flow to the heart.

Harvey followed blood through progressively smaller arteries and veins, but he had no microscope and could therefore only assume that connections must exist between them. Just a few years after Harvey's death, Italian physician Marcello Malpighi used a microscope to observe the tiny capillaries that provided the elusive links.

Various studies of blood circulation predate Harvey. For example, Greek physician Praxagoras discussed arteries and veins but proposed that arteries carried air. In 1242, Arab Muslim physician Ibn el-Nefis described blood flow between the heart and lungs.

Description of the article image: William Harvey correctly described blood circulation in the body in detail, including the movement of oxygenated blood away from the heart and the return of deoxygenated blood to it.

Historical figures mentioned in the article: Praxagoras (340 B.C.–280 B.C.), Ibn al-Nafis (1213–1288), Hieronymus Fabricius (1537–1619), William Harvey (1578–1657), Marcello Malpighi (1628–1694)

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