harvey and the mystery of circulation -- 8/10/22
Today's selection -- from Empire of The Scalpel by Ira Rutkow. In the seventeenth century, William Harvey overturned ideas on blood circulation that had been accepted for over a thousand years:
"The seventeenth is best termed 'the century of the mind.' Parades of geniuses populated every discipline. Religion and philosophy had Descartes, Leibniz, Locke, and Spinoza; Rembrandt, Teniers, Vermeer, and Wren embodied the visual arts; music was represented by Cavalli, Monteverdi, Purcell, and Stradivari; and de Bergerac, la Rochefoucauld, Milton, and Pepys exemplified literature and the theater. In the sciences, Kepler, Galileo, Halley, and Newton explained the motion of the planets and laws of gravity as astrology gave way to astronomy; Beguin, Boyle, Sendivogius, and van Helmont transformed alchemy into chemistry; and Cavalieri, Fermat, Huygens, and Pascal developed novel methods of numerical calculation to create modern mathematics and mechanics. Collectively, these men and their ideas supported the burgeoning Scientific Revolution. Experimentation and observation supplanted blind faith. The subjective became the objective as Galenism was shattered. A moment of truth was upon Medicine, one that had a crucial impact on the craft of surgery.
"The man who introduced the new methods of scientific research was William Harvey, an English physician. He based his work on the anatomical studies of Vesalius and through dogged and sharp-eyed observations solved the most elusive and fundamental of the mysteries in Medicine: how blood flowed through the human body. It is hard to grasp the enormity of Harvey's achievement without recognizing the prevailing wisdom that his work struck down. Prehistoric humans undoubtedly realized that blood was in motion because, when they butchered a live animal, they saw pulsating arteries and oozing veins. Galen noted that a beating heart contracted in a staggered motion, which led to his hypothesis that two types of blood, arterial (life-giving) and venous (nourishing), were involved in a to-and-fro action.
|An experiment from Harvey's de Motu Cordis|
"Galen's thinking still held sway through the beginning of the seventeenth century. He believed that blood was produced in the liver from digested food brought to it via the intestines. In actual fact, the constituents of blood, red blood cells, most white blood cells, and platelets are produced in the bone marrow, the spongy tissue inside the cavities of bone. Galen stated that the dark red blood coming from the liver flowed through the veins of the body and was responsible for factors related to growth and nutrition and that this venous blood was consumed in its travels. He further maintained that the right side of the heart did not pump blood but was a specialized segment of the venous system with one major function, to convey nourishment to the lungs. Galen also hypothesized that a portion of the venous blood from the right side of the heart seeped across invisible openings in the septum, the muscular dividing wall between the right and left sides. On the left side of the heart, the venous blood that oozed through the septum mixed with 'spirit-filled' air from the lungs and was transformed into bright red life-sustaining arterial blood. The arterial blood, warmed by the body's natural heat, left the heart and pulsed along the arteries where, in a tidal-like action, it provided vitality to the tissues and was eventually depleted and did not recirculate.
"Galen's model was highly imaginative and wildly inaccurate but remained the archetype of the human cardiovascular system for nearly one and a half thousand years. He had no understanding of the true movement of blood and how it coursed from the right side of the heart to the lungs, where it gained oxygen, and then circled to the left side of the heart to be circulated throughout the body before returning, deprived of oxygen, to the right side of the heart.
"The solution of the mystery of circulation was left to Harvey, a scholar who had a deep understanding of the history and literature of the subject. From Hippocrates to Galen, he knew these men, their writings, their successes, and their failures. Mindful of past inaccuracies, Harvey used human dissection, reasoned experimentation, and mathematical analysis to show that the heart is a complex, muscular pump and propels blood continuously through the vascular system in a circle-like fashion. In 1628, when Harvey authored his Exercitatio Anatomica de Motu Cordis et Sanquinis in Animalibus (Anatomical studies on the motion of the heart and blood in animals), it was as important an event to the future of Medicine as the printing of Vesalius's DeFabrica.
"If a man is judged by his appearance and personality then Harvey was an also-ran. Stout and swarthy with an abruptness and testiness that exasperated his colleagues, he offset his eccentricities with sheer brilliance. Harvey's father was a prosperous merchant and his son was well educated. In 1588, the ten-year-old Harvey was sent to the King's School at Canterbury, where students lived a monk-like existence and were encouraged to converse only in Greek or Latin. Five years later, Harvey enrolled at Gonville & Caius College, a constituent unit of the University of Cambridge, and his interest in Medicine was soon piqued. Six decades earlier, John Caius, a respected anatomist and founder of the school, had roomed with Vesalius when the two men studied Medicine in Padua. Through Caius's auspices, Elizabeth I granted the faculty at Gonville & Caius the right to anatomize two executed criminals each year. These dissections were carried out in front of the student body. Thus, by the time of Harvey's graduation in 1597, he had received considerable introduction to the nuances of human anatomy."