Harvey presents the beating heart of a small animal to expound his theory of circulation before King Charles I, by Ernest Board (1877-1934). • WIKIMEDIACOMMONS In 1628, the English physician and anatomist William Harvey published in Frankfurt his Anatomical Exercise on the Movement of the Heart and Blood in Animals . In this work containing a little more than 70 pages and 4 illustrations, he exposed his demonstration of the blood circulation in the human body, thus dismissing the erroneous doctrines which the schools of medicine had followed since antiquity. As in other fields of knowledge, Eastern science had been ahead of its European counterpart for centuries. Written 2600 BC. AD, one of the main manuals of Chinese medicine states that "all the blood in the body is directed by the heart, goes in a circle and never stops". Similarly, in the 13 th century, the Arab physician Ibn an-Nafis also described the small circulation, that is to say the pulmonary circulation. Read also:Healing in the land of Islam:medieval Arab medicine In the West, the dogmas of Claude Galen (a Greek doctor of the II th century AD. AD) were only questioned by Michael Servet (1511-1553), who asserted that venous blood passed through the lungs, where it was purified and returned to the heart. Dissuaded by a deep fear of the galenic tradition which then dominated Europe, this philosopher and doctor of Spanish origin omitted however to specify the paths taken by such circulation. Autopsies of criminals Followed for centuries, Galen's theses established that food absorbed by the stomach and intestines was transformed by the liver. This in turn made the blood, the "dark substance", which begat all the tissues and nourished them, thus ensuring their growth. The principle of blood return did not yet exist:the veins were considered to transport blood, while the arteries were empty (hence their name, arteria , "which conducts the air"). In constant consumption, the blood therefore had to be produced constantly. However, an excessive amount of blood could affect the balance of the entire metabolism, which had to be restored by bleeding. Faced with this millennial tradition, entirely disconnected from experience, anatomists like André Vésale (1514-1564) began to demonstrate that the organs obeyed a more complex functioning, likening the body to a veritable factory. Born in Folkestone, England, William Harvey was greatly influenced by the skepticism and techniques of this Flemish doctor. His extraordinary abilities allowed him to study in the prestigious faculties of Cambridge, then to complete his training at the University of Padua, where he completed his doctorate in 1602. After his return to England, he devoted himself to university teaching:he gave weekly theoretical courses and performed six autopsies each year on the corpses of executed criminals. Suffering from several illnesses, he attempted suicide in 1651 with laudanum (a syrup of opium), but did not succumb until six years later from a stroke. The heart, motor of circulation William Harvey made an essential contribution to the advancement of medical knowledge. He accepted as indisputable only the conclusions drawn from repeated experiments, in accordance with critical and objective guiding principles, which he included in the prologue of his work. To achieve this, the English anatomist dissected many human beings and up to 40 animal species. Harvey demonstrated that the human body was the seat of a double blood circulation passing through the veins (carrying blood from the organs to the heart) and the arteries (distributing blood to the whole body). He located the motor of this circulation at the level of the heart, and not of the liver. Harvey further demonstrated that blood was a constant element, in perpetual motion, thus contradicting the thesis of permanent production, based on the theories of Galen. To do this, he relied on his observations:he calculated that the hourly volume pumped by the heart (around 270 liters) was three times the weight of a normal man, an amount of blood that was impossible to produce in such a short time. This observation led him to consider that the continuous circulation of a smaller volume of blood was a reasonable hypothesis. The beating of the heart allowed this blood to be sent through the arteries, then to return it to its starting point through the veins. It was thought until then that the blood was constantly produced by the liver and that the arteries were empty. He made his observations based on phlebotomies (or venous bleeding), palpitations of arterial aneurysms (abnormal dilatations of the arteries) and pulse measurements at the temples, neck and wrists. The phenomenon of circulation allowed him to explain the ability of infections and poisons localized at a specific point in the body (such as snake bites) to affect the whole organism. Despite everything, he left other questions unanswered, such as those of the function of the liver, the role of respiration or even the mode of supply of the organs of the human body (since the latter did not consume blood). Harvey's findings were otherwise incomplete, as he never managed to demonstrate the connection between the veins (through which flowed "galenic" blood, which was very dark and unoxygenated) and the arteries (which carried oxygenated blood, scarlet), located downstream of the lungs. It was not until, four years after the death of the anatomist, that Marcello Malpighi (1628-1694) revealed the link uniting the venous and arterial systems through the use of the microscope, which enabled him to discover tiny vessels:the capillaries blood. The Sun King is conquered This progress clashed with the traditional climate of the time:after the publication of his work, Harvey was the subject of accusations made by Anglican ministers and doctors. His private consultations aroused animosity, and he was accused of being a healer. The continent echoed the resistance aroused by its discoveries, and eminent contemporary authors took a stand. If Molière and Boileau supported the theses of the Briton, Descartes ended up rejecting the theory of the motor function of the heart, whereas he had initially accepted the idea of blood circulation. Charles I st of England and Louis XIV, however, recognized the academic value of Harvey's ideas; in 1672, the Sun King decided that blood circulation would be the subject of a course given in Paris in the Jardin du Roi (the future Museum of Natural History) by the physician Pierre Dionis. Paradoxically, Harvey showed little innovation in applied medicine. He supported the practice of bloodletting, a traditional treatment for inflammations, fevers and many other ailments, and even haemorrhages. The publication of his work sparked a debate around the most appropriate points for incisions, to be made away from any injury or on the other side of the body. Harvey was not bolder in therapy and did not consider the possibility of blood transfusions. Led by Richard Lower (1631-1691), the first attempts in this area ended in success attributable to chance alone, insofar as this British surgeon used dog and lamb blood. The conservatism that dominated the practice of medicine may explain why half a century after Harvey's death, Louis XIV, who was nevertheless his academic supporter, continued to submit to traditional remedies:the monarch underwent 2,000 purges, hundreds of enemas and 38 bloodlettings. Advances in anatomy and physiology thus took centuries to translate into practice. Find out more Blood and Men, J.-L. Binet, Gallimard, 2001. Timeline 1543 In his De humani corporis fabrica , Vesalius discards the ideas of Galen and proposes a new vision of anatomy.1578 William Harvey was born in Folkestone. His abilities allow him to study in the best schools and universities.1628 William Harvey publishes a work proposing new theories relating to the functioning of blood circulation.1657 Harvey dies. Fifteen years later, blood circulation was taught at the Academy of Louis XIV.1661 Marcello Malpighi proves the link between veins and arteries thanks to the microscope and Harvey's theories. A witch-hunting doctor Harvey's fame earned him the position of king's physician from 1618 to 1649. He notably watched over the health of Jacques I st . It was at court that he touched on the question of witchcraft:appointed expert by the king in various trials, Harvey saved the lives of many women accused of witchcraft, who would not have been spared without his intervention. He revealed one day a deception around the alleged incarnation of a demon in a toad:he opened the animal by means of a scalpel which he always carried in his pocket and thus proved that it was a quite ordinary batrachian. Animal experiments In 1628, William Harvey published his Anatomical Exercise on the Movement of the Heart and Blood in Animals . This book describes his experiments in vivisection of animals of various species and describes in detail the mechanism of the animal circulatory system, which he extrapolates to that of humans. One way blood flow Harvey intended to demonstrate that the blood borrows the veins to return to the heart and that the venous valves impose a path to this organ:"The valves are designed so that the blood moves in a single direction, from the extremities towards the center of the heart. body, since such a movement easily opens the valves and the contrary movement closes them. »
