Friday, December 18, 2015

1628: William Harvey discovers circulation, and proves it

Robert Hooke discovered the respiration
was not to keep the circulation of the
blood moving.In 1553 
While a book published by Andreas Vesaleas began a quest to learn about the human body, the discovery that the blood circulates by William Harvey would was a revolutionary breakthrough that allowed scientists and physicians to truly understand te human body, and how changes within caused disease.

Galen alluded to the idea that blood circulated through the body in the 2nd century. Yet in his many writings he described blood as moving back and forth between organs in a to and fro motion. Whether he had a notion it circulated is left to speculation.

Vesaleas was the first person to publish an accurate anatomy of the body. He performed autopsies, and had a painter paint what he saw, and this was published in a book, De humani corporis fabrica, in 1543. However, he erred in believing that the purpose of circulation was to cool the blood. (7, page 474)(11, page 243-4)

A contemporary of Vesaleas was Realdus Columbus (1516-1569).  He was a surgeon and professor of anatomy at Padua from 1544 until his death in 1569. He continued Servetus's work on circulation of the blood, describing the passage of blood from the vena-cave through the pulmonary circulation, and then through the left ventricle and aorta. (8, page 70-71)

Columbus also saw that blood changes in the lungs.  (11, page 243)

Andrea Cesalpino (1519-1603) was the first to describe the idea that blood circulates through the body.  But he usually doesn't get credit for this observation because he failed to prove it.

Hieronymus Fabricius (1537-1619) studied the venous system of the human body, and discovered membranous folds that he referred to as valves. He speculated that these allowed blood to flow upward. Since the blood pressure was lower the farther blood gets from the heart, these valves were necessary to prevent gravity from pulling blood on it's way back up the legs to the heart and lungs from being pulled back down to the lower legs and feet (and thus causing dropsy of the feet). (14, page 92)

In other words, his discovery of valves made Fabricus wonder if the blood circulated as opposed to moved in a to and fro motion as Galen had suggested. But whether this was true or not would be left to one of his students to determine, one of whom was William Harvey. (14, page 93)(15, page xxiii)

Michael Servetus discovered circulation to the publication of his 1553 book, although he also failed to prove it.  So the door was still wide open for a major breakthrough in science, and just the man to accomplish this task was William Harvey, who essentially took over the work of Servetus.

William Harvey (1578-1657)(11, page 242)
Medical Historian Thomas Bradford said Harvey was born in 1578 at Folkestone in Kent, and by the time he was ten-years-old he was accepted at Caius College, Cambridge, in 1593. He studied there for five years, then traveled to France and Germany, and then studied at the "celebrated" medical school at Padua. (14, page 119)

Bradford said that he studied under some of the most renowned anatomists of the era, including Dr. Fabricius. 14 page 91)(15, page xxiii)

Some say he lectured by candle light. Perhaps it was in this "light" that William Harvey was introduced to veins and valves. This wisdom, coupled with the enthusiasm of his instructor, inspired Henry to further investigate these veins and valves to learn more about them. "Perhaps," Harvey must have wondered, "Fabricius is right, that the blood does circulate." (14, page 119)

Bradford said he graduated from Padua in 1602 and began a practice in Cambridge in London.  Then, in he became a physician at Bartholomew's Hospital, and in 1615 became professor of anatomy and surgery at the college.  It was here he began his own anatomical research.  (14, page 119)

Like Andreas before him, he wasn't satisfied with the current method of just speculating about the movement of the blood and heart, or that assuming it was knowledge only God was privy to. He studied the heart and vessels in animals, and came to the conclusion that the heart was a pump, and it circulates the blood through the body. (9, page 168-169)

While his comrades initially rejected his theory that blood circulates through the body, Bradford said:
King Charles took great interest in these discoveries and witnessed several experiments. He appointed Harvey his physician in 1643.  In 1633 he accompanied the king and his court to Scotland.  When "Old Parr" died the king gave the body to Harvey to dissect.  (14, page 120)
Several years after he made this discovery, and when he was 50 years old, he would publish, in 1628, Exercitatio anatomica de Motu Cordis et Sanguinis (An Anatomical Exercise on the Motion of the Heart and Blood in Living Beings).  (14, (page 119-122)

Of course, once Harvey published his discovery in his 1628 book  his medical practice took a hit, and he was criticized by a dogmatic medical profession.  (11, page 246)(14, pages 119-120)(17)

However, in the end, Harvey would be proved right, and his ideas (of course based on science as opposed to theory) would win out, and he lived long enough to see his theory become accepted, said Garrison. (11, page 246) (also see 14, pages 119-120)

Perhaps it was due to his friendship with the king that his ideas were accepted before his death in 1657. (14, page 119-122)

Garrison said William Harvey "was the "greatest name in the seventeenth century... and whose work has exerted a profounder influence upon modern medicine than that of any other man save Vesalius.. it was the most momentous discovery since Galen's time." (11, )

Charles Auffray and Denis Noble, in a 2009 article in International Journal of Molecular Science, said that Harvey may even have come close to discovering how the heart may continue beating even after it is removed from the body.  They quote Harvey as saying:
The heart of an eel and of certain other fish and animals, having been taken out of the body, beats without auricles.  Furthermore, if yo ucut it in pieces, you will see the separate pieces each contract and relax, so that in them the very body of the heart beats and leaps after the auricles have ceased to move. (17)
Auffray and Noble said:
He (Harvey) could not, in his day, take this dissection further down to discover that the rhythmic mechanism was integrated at the level of individual cells, since the cell theory was formulated by Matthias Schleiden (1804-1881) and Theodor Schwann (1810-1882) two centuries later based on observations with the microscope introduced  in practice in the life sciences of Anton van Leeuwenhoek (1632-1723) only after Harvey's death.  However, he was the first to realise that rhythmicity was a property of the smallest structures he could discern. (17)
Had he had access to the microscope, perhaps Harvey would have made similar discoveries.  Yet he did not need to make any further discoveries, considering his discovery of circulation, and his proving it, was enough to secure his spot in history books.

Despite his accomplishments, Harvey's view that the purpose of breathing was to cool the blood "retarded the development of the true physiology of respiration for a long time." (11, page 242-244)

However, Garrison further explains that Harvey's proof that all blood passes through the lungs, and circulates around the body, made it possible for physiology to become a "dynamic science."  (11, pages 244-248)

It was through this discovery  that made it possible for later investigators to inject dyes and other solutions into the vessels that resulted in many anatomical discoveries, such as:  (11, pages 244-248)
  • Lacteal Vessels by Gasparo Aspelli in 1622
  • Thoracic Duct by Jean Pecquet 
  • The Pancreatic Duct by Georg Wirsung in 1642
  • Circle of Willis in by Thomas Willis in 1664
  • Capillaries in the lungs by Marcello Malpighi in 1661 (see below)
Of course each of these discoveries dispelled some ancient myth about the flow of substances through the body. For instance, Galen believed the purpose of "veins and lymphatics of the intestines carried chyle to the liver, said Garrison. This theory of Galen was disproved by the above discoveries, all thanks to the discovery that blood circulates through the body by Harvey. (11, page 246-7)

Galen believed the pulse would help determine changes in the pneuma, indicating disease. Harvey, on the other hand, described that the beating of the heart correlates with the pulse felt at the various points on the body. As the pulse is felt, this is when blood is forced through the many vessels of the body during contraction of the heart. The heart then relaxes, and this is when the heart receives blood. The strength and force of the pulse, therefore, is a direct correlation to the strength and force of the heart. (9, page 168-169)

He generally agreed with Columbus that the right ventricle of the heart pumps blood to the pulmonary arteries and then to the lungs where the blood is nourished, and the left side of the heart pumps blood to the various arteries of the body. As quoted by Osler: (9, page 170)
"I began to think whether there might not be A Movement, As It Were, In A Circle. Now this I afterwards found to be true; and I finally saw that the blood, forced by the action of the left ventricle into the arteries, was distributed to the body at large, and its several parts, in the same manner as it is sent through the lungs, impelled by the right ventricle into the pulmonary artery, and that it then passed through the veins and along the vena cava, and so round to the left ventricle in the manner already indicated." (10)
Marcello malpighi was the first to observe
capillary anastomosis, although he did not
attach importance to it.
Garrison added:
The most brilliant outcome of Harvey's experimental method was in the clearing up of the obscure matter of the physiology of respiration... Before Harvey's day, men still believed, with Galen (including Vesalius and Harvey), that the object of respiration was to cool the fiery heart, the purpose of the chest movements being to introduce air for generating vital spirits by the pulmonary vein, and to get rid of the heart's smoky vapors by the same channel. This Galenic notion was not a mere piece of symbolism, as in Richard Crashaw's (1612-1649) poem on St. Teresa (The Flaming Heart), but was part and parcel of actual belief about the physics of the circulation. "Before Harvey's time," says (Sir Clifford) Allbutt (1836-925), "respiration was regarded not as a means of combustion but of refrigeration. How man became such a fiery dragon was the puzzle." Harvey's demonstration showed that the blood is changed from venous to arterial in the lungs, but beyond that point, as even (Samuel) Pepys (1633-1703) has recorded in his Diary, no one could tell how or why we breathe (13, page 266)
Per Garrison, Pepy's wrote regarding respirations:
But what among other fine discourse pleased me most was Sir G. Ent about Respiration; that it is not till this day known or concluded among physicians, nor to be done either, how the action is managed by nature, or for what use it is." (13, page 266) 
While the Fabrica of Vesalias opened the eyes of the anatomist, the discovery that blood circulates inspired the anatomist to learn more about the physiology, or the functions of the body. In this way, he inspired people to learn more about medicine, and how medicine affects the various organs of the body. Harvey, therefore, is often referred to by many as the modern father of medicine.  (15, page xxiii)

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  2. Lagerkvist, Ulf, "The Enigma of Ferment," 2005, Singapore, World Scientific Publishing
  3. Potter, Elizabeth, "Gender and Boyle's Law of Gases," 2001, Indiana University Press
  4. Newman, William R, et al, "Alchemy Tried in the Fire," 2002, University of Chicago
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  9. Osler, William Henry, "The evolution of Modern Medicine: A series of lectures delivered at Yale University on the Sillman Foundation in April, 1913," 1921, New Haven, Yale University Press
  10. Osler, ibid, pages 170, reference referring to William Harvey: Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus, Francofurti, 1628, G. Moreton's facsimile reprint and translation, Canterbury, 1894, p. 48. 20 Ibid., p. 49.
  11. Garrison, Fielding Hudson, "Introduction to the history of medicine," 1921, London, 
  12. Baker, Christopher, editor, "The Great Cultural Eras of the Western World: Absolutism and the Scientific Revolution 1600-1720: A biographical dictionary," 2002, CT, Greenwood Publishing; Herman Boerhavve published Biblia Naturae (Bible of Nature) in 1737, which was a two volume compilation of the works of Jan Swammerdam. Can you read Latin?
  13. Garrison, op cit, 266; (Samuel) Pepy's Diary, Mynors Bright's ed., London, 1900, v, 191
  14. Bradford, Thomas Lindsley, writer, Robert Ray Roth, editor, “Quiz questions on the history of medicine from the lectures of Thomas Lindley Bradford M.D.,” 1898, Philadelphia, Hohn Joseph McVey
  15. Brock, Arthur John, "Galen on the natural faculties," 1916, London, New York, William Heinemann, G.P. Putnam's Sons
  16. "History of Chemistry,",, accessed 7/6/14
  17. Affray, Charles, Denis Noble, "Origins of Systems Biology in William Harvey's masterpiece on the Movement of the Heart and the Blood in Animals," April 17, 2009, International Journal of Molecular Sciences, 10(2), pages 1658-1669, found online at,, accessed 7/8/14
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