William Harvey

William Harvey (April 1, 1578–June 3, 1657) was a medical doctor who is credited with first correctly describing, in exact detail, the properties of blood being pumped around the body by the heart. This developed the ideas of the Spanish physician Michael Servetus and those of René Descartes who in his Description of the Human Body said that the arteries and veins were pipes which carried nourishment around the body.

Early life and education

Harvey was born in Kent, England, and educated at The King's School, Canterbury, at Gonville and Caius College, Cambridge, from which he received a B.A. in 1597, and at the University of Padua (also attended by Copernicus), where he studied under Fabricius, graduating in 1602. He returned to England and married Elizabeth Browne, daughter of the court physician to Elizabeth I.

He became a doctor at St Bartholomew's Hospital at London (1609–43) and a Fellow of the Royal College of Physicians.

New circulatory model

Many believe that both Servetus and Descartes merely re-discovered and extended early Muslim medicine especially the work of Ibn Nafis, who had laid out the principles and major arteries and veins in the 13th century.

Harvey announced his discovery of the circulatory system in 1616 and in 1628 published his work Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus (An Anatomical Exercise on the Motion of the Heart and Blood in Animals), where, based on scientific methodology, he argued for the idea that blood was pumped around the body by the heart before returning to the heart and being recirculated in a closed system.

This clashed with the accepted model going back to Galen, who identified venous (dark red) and arterial (brighter and thinner) blood, each with distinct and separate functions. Venous blood was thought to originate in the liver and arterial blood in the heart; the blood flowed from those organs to all parts of the body where it was consumed. It was for exactly these reasons that the work of Ibn Nafis had been ignored.

Harvey based most of his conclusions on careful observations made of the human body during controlled experiments. He proposed that blood flowed through the heart in two seperate closed loops. One loop, pulmonary circulation, connected circulatory system to the lungs. The second loop, systemic circulation, causes blood to flow to the vital organs and body tissue. He also observed that blood in veins would move readily towards the heart, but veins would not allow flow in the opposite direction. Harvey further concluded that the heart actually acted like a pump that forced blood to move throughout the body instead of the prevailing theory of his day that blood flow was caused by a sucking action of the heart and liver. These important theories of Harvey represent two significant contributions to the understanding the mechanisms of circulation.

Embryology

Harvey also conducted research in embryology in his later career, writing On the Generation of Animals (De Generatione) in 1651. He supported the Aristotelian theory that embryos formed gradually and did not possess the characteristics of an adult in early stages. He also hypothesized the existence of a mammalian egg, and dissected dozens of deer in the King's hunting park in hopes of finding one, although he failed to do so.

Criticism of Harvey's work

Harvey's ideas were eventually accepted during his life-time. His work was attacked, notably by Jean Riolan in Opuscula anatomica (1649) which forced Harvey to defend himself in Exercitatio anatomica de circulatione sanguinis (also 1649) where he argued that Riolan's position was contrary to all observational evidence. Harvey was still regarded as an excellent doctor, he was personal physician to James I (1618-25) and Charles I (1625-47) and the Lumleian lecturer to the Royal College of Physicians (1615-56). Marcello Malpighi later proved that Harvey's ideas on anatomical structure were correct; Harvey had been unable to distinguish the capillary network and so could only theorize on how the transfer of blood from artery to vein occurred.

Even so, Harvey's work had little effect on general medical practice at the time — blood letting, an idea based on the incorrect theories of Galen, was a popular practice, and continued to be so even after Harvey's ideas were accepted. Harvey's work did much to encourage others to investigate the questions raised by his research, and to revive the Muslim tradition of scientific medicine expressed by Nafis, Ibn Sina, and Rhazes. (See also: François Bernier)

Honours

Harvey was ranked #55 on Michael H. Hart's list of the most influential figures in history. Pulitzer Prize-winning historian Arthur Schlesinger Jr. also included him in his list of "The Ten Most Influential People of the Second Millennium" in the World Almanac & Book of Facts.

Writings

1628 Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus
1651 De Generatione

External links