Editing Circulatory system (section)

==History==

[[File:Charta ex qva figvram parare convenit, illi qvae nervorvm seriem exprimit appendendam, 1543..JPG |thumb |right |Human anatomical chart of blood vessels, with heart, lungs, liver and kidneys included. Other organs are numbered and arranged around it. Before cutting out the figures on this page, [[Vesalius]] suggests that readers glue the page onto parchment and gives instructions on how to assemble the pieces and paste the multilayered figure onto a base "muscle man" illustration. "Epitome", fol.14a. HMD Collection, WZ 240 V575dhZ 1543.]]

The earliest known writings on the circulatory system are found in the [[Ebers Papyrus]] (16th century BCE), an [[Ancient Egyptian medicine |ancient Egyptian medical papyrus]] containing over 700 prescriptions and remedies, both physical and spiritual. In the [[papyrus]], it acknowledges the connection of the heart to the arteries. The Egyptians thought air came in through the mouth and into the lungs and heart. From the heart, the air travelled to every member through the arteries. Although this concept of the circulatory system is only partially correct, it represents one of the earliest accounts of scientific thought.{{cn|date=January 2025}}

In the 6th century BCE, the knowledge of circulation of vital fluids through the body was known to the [[Ayurveda |Ayurvedic]] physician [[Sushruta]] in [[History of India |ancient India]].<ref name=Dwivedi&Dwivedi07/> He also seems to have possessed knowledge of the arteries, described as 'channels' by Dwivedi & Dwivedi (2007).<ref name=Dwivedi&Dwivedi07>Dwivedi, Girish & Dwivedi, Shridhar (2007). [https://medind.nic.in/iae/t07/i4/iaet07i4p243.pdf "History of Medicine: Sushruta&nbsp;– the Clinician&nbsp;– Teacher par Excellence"] {{webarchive |url=https://web.archive.org/web/20081010045900/https://medind.nic.in/iae/t07/i4/iaet07i4p243.pdf |date=October 10, 2008 }}, ''Indian J Chest Dis Allied Sci'' Vol. 49 pp. 243–244, [[National Informatics Centre |National Informatics Centre (Government of India)]].</ref> The first major ancient Greek research into the circulatory system was completed by Plato in the ''Timaeus'', who argues that blood circulates around the body in accordance with the general rules that govern the motions of the elements in the body; accordingly, he does not place much importance in the heart itself.<ref>See ''Timaeus'' 77a–81e. For a scholarly discussion, see Douglas R. Campbell, "Irrigating Blood: Plato on the Circulatory System, the Cosmos, and Elemental Motion," ''Journal of the History of Philosophy'' 62 (4): 519-541. 2024. See also Francis Cornford, ''Plato's Cosmology: The Timaeus of Plato,'' Indianapolis: Hackett, 1997.</ref> The [[Heart valve |valves of the heart]] were discovered by a physician of the [[Hippocrates |Hippocrat]]<nowiki/>ic school around the early 3rd century BC.<ref>The central text here is the Hippocratic text ''On The Heart'', which Elizabeth Craik argues was written between 300 and 250 BC. See Craik, Elizabeth. 2015. ''The ‘Hippocratic’ Corpus: Content and Context''. New York: Routledge.</ref> However, their function was not properly understood then. Because blood pools in the veins after death, arteries look empty. Ancient anatomists assumed they were filled with air and that they were for the transport of air.{{cn|date=January 2025}}

The [[Ancient Greek Medicine |Greek physician]], [[Herophilus]], distinguished veins from arteries but thought that the [[pulse]] was a property of arteries themselves. Greek anatomist [[Erasistratus]] observed that arteries that were cut during life bleed. He ascribed the fact to the phenomenon that air escaping from an artery is replaced with blood that enters between veins and arteries by very small vessels. Thus he apparently postulated capillaries but with reversed flow of blood.{{citation needed |date=February 2022}}

In 2nd-century AD [[Rome]], the [[Ancient Greek Medicine |Greek]] physician [[Galen]] knew that blood vessels carried blood and identified venous (dark red) and arterial (brighter and thinner) blood, each with distinct and separate functions. Growth and energy were derived from venous blood created in the liver from chyle, while arterial blood gave vitality by containing pneuma (air) and originated in the heart. Blood flowed from both creating organs to all parts of the body where it was consumed and there was no return of blood to the heart or liver. The heart did not pump blood around, the heart's motion sucked blood in during diastole and the blood moved by the pulsation of the arteries themselves.{{cn|date=January 2025}} Galen believed that the arterial blood was created by venous blood passing from the left ventricle to the right by passing through 'pores' in the interventricular septum, air passed from the lungs via the pulmonary artery to the left side of the heart. As the arterial blood was created 'sooty' vapors were created and passed to the lungs also via the pulmonary artery to be exhaled.{{cn|date=January 2025}}

In 1025, ''[[The Canon of Medicine]]'' by the [[Ancient Iranian Medicine |Persian physician]], [[Avicenna]], "erroneously accepted the Greek notion regarding the existence of a hole in the ventricular septum by which the blood traveled between the ventricles." Despite this, Avicenna "correctly wrote on the [[cardiac cycle]]s and valvular function", and "had a vision of blood circulation" in his ''Treatise on Pulse''.<ref>{{Cite journal |last1=Shoja |first1=M.M. |last2=Tubbs |first2=R.S. |last3=Loukas |first3=M. |last4=Khalili |first4=M. |last5=Alakbarli |first5=F. |last6=Cohen-Gadol |first6=A.A. |doi=10.1016/j.ijcard.2009.02.035 |title=Vasovagal syncope in the Canon of Avicenna: The first mention of carotid artery hypersensitivity |journal=International Journal of Cardiology |volume=134 |issue=3 |pages=297–301 |year=2009 |pmid=19332359}}</ref> While also refining Galen's erroneous theory of the pulse, Avicenna provided the first correct explanation of pulsation: "Every beat of the pulse comprises two movements and two pauses. Thus, expansion : pause : contraction : pause. [...] The pulse is a movement in the heart and arteries ... which takes the form of alternate expansion and contraction."<ref name="Chamsi-Pasha2014">{{cite journal |last1=Chamsi-Pasha |first1=MA |last2=Chamsi-Pasha |first2=H |title=Avicenna's contribution to cardiology. |journal=Avicenna Journal of Medicine |date=January 2014 |volume=4 |issue=1 |pages=9–12 |doi=10.4103/2231-0770.127415 |doi-access=free |pmid=24678465|pmc=3952394 }}</ref>

In 1242, the [[Medicine in medieval Islam |Arabian physician]], [[Ibn al-Nafis]] described the process of [[pulmonary circulation]] in greater, more accurate detail than his predecessors, though he believed, as they did, in the notion of vital spirit ([[pneuma]]), which he believed was formed in the left ventricle. Ibn al-Nafis stated in his ''Commentary on Anatomy in Avicenna's Canon'':<ref name="West 2008"/>

<blockquote>...the blood from the right chamber of the heart must arrive at the left chamber but there is no direct pathway between them. The thick septum of the heart is not perforated and does not have visible pores as some people thought or invisible pores as Galen thought. The blood from the right chamber must flow through the vena arteriosa (pulmonary artery) to the lungs, spread through its substances, be mingled there with air, pass through the arteria venosa ([[pulmonary vein]]) to reach the left chamber of the heart and there form the vital spirit...</blockquote>

In addition, Ibn al-Nafis had an insight into what later became a larger theory of the [[capillary]] circulation. He stated that "there must be small communications or pores (''manafidh'' in Arabic) between the pulmonary artery and vein," a prediction that preceded the discovery of the capillary system by more than 400 years.<ref name="West 2008">{{Cite journal |last1=West |first1=J.B. |title=Ibn al-Nafis, the pulmonary circulation, and the Islamic Golden Age |doi=10.1152/japplphysiol.91171.2008 |journal=Journal of Applied Physiology |volume=105 |issue=6 |pages=1877–1880 |year=2008 |pmid=18845773 |pmc =2612469}}</ref> Ibn al-Nafis' theory was confined to blood transit in the lungs and did not extend to the entire body.

[[Michael Servetus]] was the first European to describe the function of pulmonary circulation, although his achievement was not widely recognized at the time, for a few reasons. He firstly described it in the "Manuscript of Paris"<ref>Gonzalez Etxeberria, Patxi (2011) ''Amor a la verdad, el&nbsp;– vida y obra de Miguel servet'' [''The love for truth. Life and work of Michael Servetus'']. Navarro y Navarro, Zaragoza, collaboration with the Government of Navarra, Department of Institutional Relations and Education of the Government of Navarra. {{ISBN |84-235-3266-6}} pp. 215–228 & 62nd illustration (XLVII)</ref><ref>[https://www.michaelservetusresearch.com/ENGLISH/works.html Michael Servetus Research] {{Webarchive |url=https://web.archive.org/web/20121113223851/https://www.michaelservetusresearch.com/ENGLISH/works.html |date=2012-11-13 }} Study with graphical proof on the Manuscript of Paris and many other manuscripts and new works by Servetus</ref> (near 1546), but this work was never published. And later he published this description, but in a theological treatise, ''Christianismi Restitutio'', not in a book on medicine. Only three copies of the book survived but these remained hidden for decades, the rest were burned shortly after its publication in 1553 because of persecution of Servetus by religious authorities.{{cn|date=January 2025}}

A better known discovery of pulmonary circulation was by [[Vesalius]]'s successor at [[University of Padua |Padua]], [[Realdo Colombo]], in 1559.{{cn|date=January 2025}}

[[File:William Harvey ( 1578-1657) Venenbild.jpg |thumb |Image of veins from [[William Harvey]]'s ''[[Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus]]'', 1628]]

Finally, the English physician [[William Harvey]], a pupil of [[Hieronymus Fabricius]] (who had earlier described the valves of the veins without recognizing their function), performed a sequence of experiments and published his ''[[Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus]]'' in 1628, which "demonstrated that there had to be a direct connection between the venous and arterial systems throughout the body, and not just the lungs. Most importantly, he argued that the beat of the heart produced a continuous circulation of blood through minute connections at the extremities of the body. This is a conceptual leap that was quite different from Ibn al-Nafis' refinement of the anatomy and bloodflow in the heart and lungs."<ref>Pormann, Peter E. and Smith, E. Savage (2007) ''Medieval Islamic medicine'' Georgetown University, Washington, D.C., p. 48, {{ISBN |1-58901-161-9}}.</ref> This work, with its essentially correct exposition, slowly convinced the medical world. However, Harvey did not identify the capillary system connecting arteries and veins; this was discovered by [[Marcello Malpighi]] in 1661.{{cn|date=January 2025}}