"discoverer of the circulatory system"

William Harvey was born in Folkestone, England, on April 1, 1578. After graduation from Caius College, Cambridge, he studied medicine at the University of Padua. He returned to England in 1602, was elected a Fellow of the College of Physicians in 1607, and in 1609 became a physician at St. Bartholomew's Hospital. Quickly earning a good reputation for himself, he was appointed by the College its Lumleian lecturer in 1615, and by 1618 he was one of the physicians for both James I and Charles I.

Harvey began his work on the human circulatory system while at the College of Physicians. Common teaching at the time held that the blood moved backward and forward like the ebb and flow of the tides. It was believed that one kind of blood was made in the liver, and another kind in the heart. Arteries were believed to carry air to all parts of the body, and that the veins carried the blood. Fabricius, one of Harvey's former teachers, had discovered the valves in the large veins, but had failed to understand their function. Harvey approached the problem without preconceptions, devising a series of experiments in which he tied up the blood vessels of living animals.

Harvey's observations and experiments showed that the heart, by repeated contractions, produces a continuous stream of blood throughout the body which continually returns to its source (the heart). Harvey was also able to show that there had to be pathways at the extremities for the blood to pass from arteries to veins -- what we now know as capillaries. Lastly, he showed that the valves in the veins always direct blood back to the heart, as opposed to the contemporary theory that they acted to prevent the lower parts of the body from flooding with blood.

Left: This series of drawings shows how Harvey proved that blood circulates around the body in the same direction. By constricting the arm above the elbow the veins stand out and the valves are seen as swellings. Fingertip pressure applied to the vein causes that portion of the vein up to the next valve to be drained of blood.

Harvey published his observations in An Anatomical Treatise on the Motion of the Heart and Blood in Animals, in 1628. Although his theories were severely attacked by followers of the ancient Greek physician Galen, they were hard to disprove since they were based on actual observation and experiment. Harvey lived to see his discovery widely accepted, although he did not receive full credit until after his death.

Ill health forced Harvey to withdraw from active life in his later years. He died of a stroke on June 3, 1657, and was buried in a family vault at Hempstead Church in Essex. His personal library, which he gave to the College of Physicians, was lost in the Great Fire of London in 1666.

James I
Charles I
Heart
Galen

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