Circulation circles in humans: evolution, structure and work of large and small, additional features. Diseases of the circulatory system Human arterial circulation

In 1623, Pietro Sarpi, a widely educated Venetian monk who had a share in the opening of venous valves, died. Among his books and manuscripts they found a copy of an essay on the movement of the heart and blood, published in Frankfurt only five years later. It was the work of William Harvey, a student of Fabrizio.

Harvey is one of the outstanding researchers of the human body. He greatly contributed to the fact that the medical school in Padua acquired such great fame in Europe. In the courtyard of the University of Padua you can still see Harvey's coat of arms, mounted above the door to the hall in which Fabrizio gave his lectures: two snakes of Aesculapian entwined around a burning candle. This burning candle, chosen by Harvey as a symbol, depicted life consumed by flame, but nevertheless shining.

William Harvey (1578-1657)

Harvey discovered a large circle of blood circulation, through which blood from the heart passes through the arteries to the organs, and from the organs through the veins returns to the heart - a fact that today is taken for granted by everyone who knows even a little about the human body and its structure. However, for that time it was a discovery of extraordinary importance. Harvey is of the same importance to physiology as Vesalius is to anatomy. He was met with the same hostility as Vesalius, and just like Vesalius, he gained immortality. But having lived to a more advanced age than the great anatomist, Harvey turned out to be happier than him - he died in the light of glory.

Harvey also had to fight the traditional view, expressed by Galen, that the arteries allegedly contain little blood, but a lot of air, while the veins are filled with blood.

Every person of our time has a question: how could it be assumed that the arteries do not contain blood? After all, with any injury that affected the arteries, a stream of blood flowed from the vessel. Animal sacrifices and slaughter also indicated that there was blood flowing in the arteries, and even quite a lot of blood. However, we must not forget that scientific views were then determined by observational data on the corpses of dissected animals and rarely on human corpses. In a dead body, as every first-year medical student can confirm, the arteries are narrowed and almost bloodless, while the veins are thick and filled with blood. This bloodlessness of the arteries, which occurs only with the last beat of the pulse, prevented a correct understanding of their significance, and therefore nothing was known about blood circulation. It was believed that blood is formed in the liver - in this powerful and blood-rich organ; through the large vena cava, the thickness of which could not fail to catch the eye, it enters the heart, passes through the thinnest openings - pores (which, however, no one has ever seen) - in the cardiac septum from the right heart chamber to the left and from here goes to the organs . In the organs, it was taught at that time, this blood is consumed and therefore the liver must constantly produce new blood.

As early as 1315, Mondino de Liuzzi suspected that this view was not true and that blood from the heart also flows to the lungs. But his assumption was very vague, and it took more than two hundred years to say a clear and distinct word about it. It was said by Servetus, who deserves to say something about him.

Miguel Servetus (1511-1553)

Miguel Servetus (actually Serveto) was born in 1511 in Villanova in Spain; his mother was from France. He received his general education in Zaragoza and his legal education in Toulouse, France (his father was a notary). From Spain, a country over which the smoke of the fires of the Inquisition hung, he found himself in a country where it was easier to breathe. In Toulouse, the mind of a seventeen-year-old youth was filled with doubts. Here he had the opportunity to read Melanchthon and other authors who rebelled against the spirit of the Middle Ages. Servetus sat for hours with like-minded people and peers, discussing individual words and phrases, doctrines and various interpretations of the Bible. He saw the difference between what Christ taught and what sophistry and despotic intolerance turned this teaching into.

He was offered the position of secretary to the confessor of Charles V, which he willingly accepted. Thus, together with the court, he visited Germany and Italy, witnessed celebrations and historical events and met the great reformers - Melanchthon, Martin Bucer, and later Luther, who made a huge impression on the fiery young man. Despite this, Servetus became neither a Protestant nor a Lutheran, and disagreement with the dogmas of the Catholic Church did not lead him to the Reformation. He, striving for something completely different, read the Bible, studied the history of the emergence of Christianity and its unfalsified sources, trying to achieve the unity of faith and science. Servetus did not foresee the dangers that this could lead to.

Reflections and doubts closed his way anywhere: he was a heretic both for the Catholic Church and for the reformers. Everywhere he met ridicule and hatred. Of course, such a person had no place at the imperial court, and even more so he could not remain the secretary of the emperor’s confessor. Servet chose a restless path, never to leave it again. At the age of twenty, he published an essay in which he denied the trinity of God. Then Bucer also said: “This atheist should be cut into pieces and his entrails should be torn out of his body.” But he did not have to see his wish come true: he died in 1551 in Cambridge and was buried in the main cathedral. Later, Mary Stuart ordered his remains to be removed from the coffin and burned: for her he was a great heretic.

Servetus printed the said work on the Trinity at his own expense, which consumed all his savings. His family abandoned him, his friends disowned him, so he was glad when he finally got a job under an assumed name as a proofreader for a Lyon printer. The latter, pleasantly impressed by his new employee’s good knowledge of Latin, instructed him to write a book about the Earth, basing it on Ptolemy’s theory. This is how a hugely successful work was published, which we would call comparative geography. Thanks to this book, Servetus met and became friends with the Duke of Lorraine’s physician, Doctor Champier. This Doctor Champier was interested in books and was himself the author of several books. He helped Servetus find his true calling - medicine and forced him to study in Paris, probably giving him the means for this.

A stay in Paris allowed Servetus to meet the dictator of the new faith, Johann Calvin, who was two years older than him. Calvin punished anyone who disagreed with his views with hatred and persecution. Servetus later also became his victim.

After completing his medical education, Servetus briefly practiced medicine, which could have brought him a piece of bread, peace of mind, confidence in the future and universal respect. For some time he practiced in Charlier, located in the fertile Loire Valley, but, fleeing persecution, was forced to return to the proofreading room in Lyon. Here fate extended a saving hand to him: none other than the Archbishop of Vienne took the heretic to his place as a physician, thereby providing him with protection and conditions for quiet work.

For twelve years Servetus lived quietly in the archbishop's palace. But the peace was only external: the great thinker and skeptic was haunted by inner restlessness; a prosperous life could not extinguish the inner fire. He continued to think and search. Inner strength, or perhaps just gullibility, prompted him to tell his thoughts to the one from whom they should have caused the greatest hatred, namely Calvin. The preacher and head of the new faith, his own faith, was sitting in Geneva at that time, ordering the burning of everyone who contradicted him.

It was a most dangerous, or rather, suicidal step - to send manuscripts to Geneva in order to dedicate a person like Calvin to what a person like Servetus thinks about God and the church. But not only that: Servetus sent Calvin his own work, his main work, with his appendix, in which all his errors were clearly and thoroughly listed. Only a naive person could think that it was only about scientific disagreements, about a business discussion. Servetus, pointing out all of Calvin's mistakes, hurt him and irritated him to the limit. This was precisely the beginning of the tragic end of Servetus, although another seven years passed before the flames closed over his head. To end the matter peacefully, Servetus wrote to Calvin: “Let us go our separate ways, return my manuscripts to me and farewell.” Calvin, in one of his letters to his like-minded person, the famous iconoclast Farel, whom he managed to win over to his side, says: “If Servetus ever visits my city, I will not let him out alive.”

The work, part of which Servetus sent to Calvin, was published in 1553, ten years after the first edition of Vesalius' anatomy. The same era gave birth to both of these books, but how fundamentally different they are in their content! “Fabrika” by Vesalius is a doctrine about the structure of the human body, corrected as a result of the author’s own observations, a denial of Galenic anatomy. The work of Servetus is a theological book. He called it "Cristianismi restitutio...". The whole title, in accordance with the tradition of that era, is very long and reads as follows: “The Restoration of Christianity, or the appeal to the whole Apostolic Church to return to its own beginnings, after the knowledge of God, faith in Christ our redeemer, regeneration, baptism, and eating the food of the Lord, and after the kingdom of heaven is finally opened for us again, deliverance from godless Babylon will be granted, and the enemy of man and his companions will be destroyed.”

This work was polemical, written in refutation of the dogmatic teaching of the church; it was secretly printed in Vienne, knowingly doomed to be banned and burned. However, three copies still escaped destruction; one of them is kept in the Vienna National Library. For all its attacks on dogma, the book professes humility. It represents a new attempt by Servetus to combine faith with science, to adapt the human to the inexplicable, the divine, or to make the divine, that is, stated in the Bible, accessible through scientific interpretation. In this work about the restoration of Christianity, quite unexpectedly, a very remarkable passage appears: “To understand this, you must first understand how the vital spirit is produced... The vital spirit originates in the left heart ventricle, and the lungs provide special assistance in the production of the vital spirit, so how the air entering them is mixed with the blood coming from the right heart ventricle. This path of blood, however, does not at all run through the septum of the heart, as is commonly thought, but the blood is driven in an extremely skillful manner by another route from the right heart ventricle to the lungs... Here it mixes with the inhaled air, while when exhaled, the blood is freed from soot" (here carbon dioxide is meant). “After the blood is well mixed through the breathing of the lungs, it is finally drawn back into the left heart ventricle.”

How Servetus came to this discovery - through observation of animals or people - is unknown: what is certain is that he was the first to clearly recognize and describe the pulmonary circulation, or the so-called pulmonary circulation, i.e. the path of blood from the right side of the heart to the lungs and from there back to the left side of the heart. But only a few doctors of that era paid attention to the extremely important discovery, thanks to which Galen’s idea of ​​the passage of blood from the right ventricle to the left through the heart septum relegated to the realm of myths, from where it came. This, obviously, should be attributed to the fact that Servetus presented his discovery not in a medical, but in a theological work, moreover, in one that was diligently and very successfully searched for and destroyed by the servants of the Inquisition.

The isolation from the world characteristic of Servetus and a complete lack of understanding of the seriousness of the situation led to the fact that during his trip to Italy he stopped in Geneva. Did he assume that he would pass through the city undetected, or did he think that Calvin's anger had long cooled down?

Here he was captured and thrown into prison and could no longer expect mercy. He wrote to Calvin, asking him for more humane conditions of imprisonment, but he did not know pity. “Remember,” the answer read, “how sixteen years ago in Paris I tried to persuade you to our Lord! If you had come to us then, I would have tried to reconcile you with all the good servants of the Lord. You poisoned and blasphemed me. Now you can beg for mercy from the Lord whom you reviled, wanting to overthrow the three beings embodied in him - the trinity.”

The verdict of the four highest church authorities that then existed in Switzerland, of course, coincided with the verdict of Calvin: he proclaimed death by burning and was carried out on October 27, 1553. It was a painful death, but Servetus refused to renounce his beliefs, which would have given him the opportunity to achieve a more lenient execution.

However, in order for the pulmonary circulation discovered by Servetus to become the common property of medicine, it had to be rediscovered. This secondary discovery was made several years after the death of Servetus by Realdo Colombo, who headed the department in Padua, which was previously in charge of Vesalius.

William Harvey was born in 1578 in Folkestone. He took an introductory course in medicine at Caius College, Cambridge, and in Padua, the center of attraction for all doctors, he received a medical education corresponding to the level of knowledge of that time. Even as a student, Harvey was distinguished by the sharpness of his judgments and critical-skeptical remarks. In 1602 he received the title of doctor. His teacher Fabrizio could be proud of a student who, just like him, was interested in all the big and small secrets of the human body and, even more than the teacher himself, did not want to believe what the ancients taught. Everything must be explored and rediscovered - this was Harvey's opinion.

Returning to England, Harvey became professor of surgery, anatomy and physiology in London. He was physician to Kings James I and Charles I, accompanying them on their travels and during the Civil War of 1642. Harvey accompanied the court on its flight to Oxford. But the war came here with all its unrest and Harvey had to give up all his positions, which, however, he did willingly, since he wanted only one thing: to spend the rest of his life in peace and tranquility, doing books and research.

A gallant and elegant man in his youth, Harvey became calm and modest in his old age, but he was always an extraordinary person. He died at the age of 79, a balanced old man, looking at the world with the same skeptical gaze with which he had looked at the theories of Galen or Avicenna.

In the last years of his life, Harvey wrote an extensive work on embryological research. It was in this book, dedicated to the development of animals, that he wrote the famous words - “ornne vivum ex ovo” (“all living things come from the egg”), which captured the discovery that has dominated biology ever since in the same formulation.

But it was not this book that brought him great fame, but another, much smaller book - a book on the movement of the heart and blood: “Exercitatio anatomica de motu cordis et sanguinis in animalibus” (“Anatomical study on the movement of the heart and blood in animals”). It was published in 1628 and gave rise to passionate and heated discussions. A new and too unusual discovery could not help but excite minds. Harvey was able to discover through numerous experiments when he studied the still beating heart and breathing lungs of animals in order to discover the truth, a large circle of blood circulation.

Harvey made his great discovery back in 1616, since even then, in one of his lectures at the London College of Physicians, he talked about the fact that blood “circles” in the body. However, for many years he continued to search and accumulate proof after proof, and only twelve years later he published the results of his hard work.

Of course, Harvey described a lot of what was already known, but mainly what he believed pointed to the right path in the search for truth. And yet he owes the greatest merit to the knowledge and explanation of blood circulation in general, although he did not notice one part of the circulatory system, namely the capillary system - a complex of the thinnest, hair-like vessels that are the ends of the arteries and the beginning of the veins.

Jean Riolan the Younger, professor of anatomy in Paris, head of the medical faculty and royal physician, led the fight against Harvey. This turned out to be serious opposition, since Riolan was, indeed, a major anatomist and an outstanding scientist who enjoyed great authority.

But gradually the opponents, even Riolan himself, fell silent and admitted that Harvey had succeeded in making one of the greatest discoveries concerning the human body, and that the doctrine of the human body had entered a new era.

Harvey's discovery was most fiercely contested by the Paris Faculty of Medicine. Even a hundred years later, the conservatism of the doctors of this faculty was still the subject of ridicule by Rabelais and Montaigne. Unlike the freer atmosphere of the Montpellier school, the faculty, in its rigid adherence to tradition, adhered unswervingly to the teachings of Galen. What could these gentlemen, proudly speaking in their precious uniforms, know about the calls of their contemporary Descartes to replace the principle of authority with the rule of human reason!

The discussion about blood circulation has gone far beyond the circles of specialists. Moliere also took part in the fierce verbal battles, and more than once directed the severity of his ridicule against the narrow-mindedness and arrogance of the doctors of that era. Thus, in “The Imaginary Invalid,” the newly minted doctor Thomas Diafuarus gives the role to the maid Toinette: the role contains a thesis he composed, directed against supporters of the doctrine of blood circulation! Even if he was confident in the approval of this thesis by the Parisian Faculty of Medicine, he could be no less confident in the crushing, destroying laughter of the public.

Circulation, as described by Harvey, is the actual circulation of blood in the body. When the heart ventricles contract, blood from the left ventricle is pushed into the main artery - the aorta; through it and its branches it penetrates everywhere - into the leg, arm, head, into any part of the body, delivering vital oxygen there. Harvey did not know that in the organs of the body the blood vessels branch into capillaries, but he correctly pointed out that the blood is then collected again, flows through the veins back to the heart and flows through the greater vena cava into the right atrium. From there, the blood enters the right ventricle and, when the ventricles contract, it is sent through the pulmonary artery, which extends from the right ventricle, to the lungs, where it is supplied with fresh oxygen - this is the pulmonary circulation, discovered by Servetus. Having received fresh oxygen in the lungs, the blood flows through the great pulmonary vein into the left atrium, from where it enters the left ventricle. After this, the systemic circulation is repeated. You just need to remember that arteries are the vessels that lead blood away from the heart (even if they, like the pulmonary artery, contain venous blood), and veins are the vessels leading to the heart (even if they, like the pulmonary vein, contain arterial blood).

Systole is the contraction of the heart; Atrial systole is much weaker than ventricular systole. The expansion of the heart is called diastole. The movement of the heart covers both the left and right sides simultaneously. It begins with atrial systole, from where blood is driven into the ventricles; followed by systole jelly daughters, and the blood is pushed into two large arteries - the aorta, through which it enters all areas of the body (systemic circulation), and the pulmonary artery, through which it passes to the lungs (lesser, or pulmonary, circulation). After this there is a pause, during which the ventricles and atria are dilated. Harvey basically established all this.

At the beginning of his not very voluminous book, the author talks about what exactly prompted him to this work: “When I first turned all my thoughts and desires to observations based on vivisections (to the extent to which I had to do them), in order to from my own contemplations, and not from books and manuscripts to recognize the meaning and benefits of cardiac movements in living beings, I discovered that this question is very complex and full of mysteries at every step. Namely, I could not make out exactly how systole and diastole occur. After day after day, exerting more and more effort to achieve greater accuracy and thoroughness, I studied a large number of the most diverse living animals and collected data from numerous observations, I finally came to the conclusion that I had attacked the trail that interested me and managed to get out from this labyrinth, and at the same time, as I wanted, I recognized the movement and purpose of the heart and arteries.”

The extent to which Harvey had the right to assert this is evidenced by his strikingly accurate description of the movement of the heart and blood: “First of all, in all animals, while they are still alive, one can observe, when opening their chest, that the heart first moves and then rests. .. Three moments can be observed in the movement: firstly, the heart rises and lifts its top in such a way that at this moment it knocks on the chest and these beats are felt from the outside; secondly, it is compressed on all sides, somewhat more so on the sides, so that it decreases in volume, stretches somewhat and wrinkles; thirdly, if you take the heart in your hand at the moment when it makes a movement, it hardens. From here it became clear that the movement of the heart consists in general (to a certain extent) tension and all-round compression in accordance with the traction of all its fibers. Corresponding to these observations is the conclusion that the heart, at the moment when it moves and contracts, narrows in the ventricles and squeezes out the blood contained in them. Hence there arises an obvious contradiction to the generally accepted belief that at the moment when the heart beats the chest, the ventricles of the heart expand, filling at the same time with blood, while one can be convinced that the situation should be just the opposite, namely, that the heart is emptied at the moment of contraction "

Reading Harvey’s book, one is constantly amazed at the accuracy of the description and the consistency of the conclusions: “So nature, which does nothing without a reason, did not provide a heart to such a living being that does not need it and did not create a heart before it acquired meaning; nature achieves perfection in each of its manifestations by the fact that during the formation of any living being, it goes through the stages of formation (if I may put it this way) common to all living beings: egg, worm, embryo.” In this conclusion one can recognize an embryologist - a researcher who studies the development of the human and animal organism, who in these remarks clearly indicates the stages of development of the embryo in the womb.

Harvey is undoubtedly one of the outstanding pioneers of human science, a researcher who opened a new era of physiology. Many later discoveries in this field were significant and even extremely significant, but nothing was more difficult than the first step, that first act that crushed the edifice of error in order to erect the edifice of truth.

Of course, Harvey's system was still missing some links. First of all, the connecting part between the arterial system and the venous system was missing. How does blood, going from the heart through large and small arteries to all parts of the organs, finally enter the veins, and from there back to the heart, in order to then stock up on new oxygen in the lungs? Where is the transition from arteries to veins? This important part of the circulatory system, namely the connection of arteries with veins, was discovered by Marcello Malpighi from Crevalcore near Bologna: in 1661, in his book on the anatomical study of the lungs, he described the hair vessels, i.e. capillary circulation.

Malpighi studied the pulmonary vesicles in detail in frogs and found that the thinnest bronchioles end in pulmonary vesicles, which are surrounded by blood vessels. He also noticed that the thinnest arteries are located next to the thinnest veins, one capillary network next to another, and quite correctly assumed that the blood vessels do not contain air. He considered it possible to make this message to the public, since even earlier he had acquainted them with his discovery of a capillary network in the mesentery of the intestines of frogs. The walls of the hair vessels are so thin that oxygen easily penetrates from them to the tissue cells; The oxygen-poor blood is then sent to the heart.

Thus, the most important stage of blood circulation was discovered, which determined the completeness of this system, and no one could refute that blood circulation does not occur as Harvey described. Harvey died several years before the discovery of Malpighi. He did not have the opportunity to witness the complete triumph of his teaching.

The opening of the capillaries was preceded by the opening of the pulmonary vesicles. Here is what Malpighi writes about this to his friend Borelli: “Every day, doing autopsies with more and more diligence, I have recently been studying with particular care the structure and function of the lungs, about which, as it seemed to me, there are still rather vague ideas. I now want to tell you the results of my research, so that you, with your gaze, so experienced in matters of anatomy, can separate right from wrong and effectively use my discoveries... Through diligent research, I discovered that the entire mass of the lungs, which hang on the vessels emanating from them, consists from very thin and delicate films. These films, sometimes straining and sometimes shrinking, form many bubbles, similar to the honeycombs of a hive. Their location is such that they are directly connected both to each other and to the windpipe, and form a generally interconnected film. This is best seen on lungs taken from a living animal; especially at their lower end, you can clearly see numerous small bubbles swollen with air. The same thing, although not so clearly, can be recognized in a lung cut in the middle and deprived of air. When the light falls directly on the surface of the lungs in a dissolved state, a wonderful network is noticeable, which seems closely connected with the individual bubbles; the same can be seen on the cut lung and from the inside, although not so clearly.

Typically, the lungs vary in shape and location. There are two main parts, between which is the mediastinum (Mediastinum); Each of these parts consists of two in humans, and several subdivisions in animals. I myself discovered a most wonderful and complex dissection. The total mass of the lungs consists of very small lobules, surrounded by a special kind of film and equipped with their own vessels formed from the processes of the windpipe.

To distinguish these lobules, you should hold the half-inflated lung against the light, and then the gaps will clearly appear; when air is blown through the windpipe, the lobules wrapped in a special film can be separated with small sections from the vessels touching them. This is achieved through very careful preparation.

As for the function of the lungs, I know that much that is taken for granted by old people is still very doubtful, especially the cooling of the blood, which according to the traditional view is considered the main function of the lungs; This view is based on the assumption of the presence of warmth rising from the heart, seeking an outlet. I, however, for reasons which I will discuss below, consider it most likely that the lungs are designed by nature for mixing the mass of blood. As for the blood, I do not believe that it consists of the four usually supposed liquids - both galenic substances, blood itself and saliva, but I am of the opinion that the entire mass of blood, constantly flowing through the veins and arteries and consisting of small particles, is composed from two very similar liquids - a whitish one, which is usually called serum, and a reddish one ... "

While printing his work, Malpighi arrived for the second time in Bologna, where he had already come at the age of twenty-eight as a professor. He did not meet with sympathy from the faculty, who immediately opposed the new teaching in the most harsh manner. After all, what he proclaimed was a medical revolution, a revolt against Galen; Everyone united against this, and the old people began a real persecution of the youth. This made it difficult for Malpighi to work calmly, and he changed the department in Bologna to the department in Messina, believing that he would find different conditions for teaching there. But he was mistaken, for even there he was pursued by hatred and envy. In the end, after four years, he decided that Bologna was still better and returned there. However, a change in sentiment had not yet occurred in Bologna, although the name Malpighi was already widely known abroad.

The same thing happened to Malpighi as to many others, both before him and after him: he became a prophet not recognized in his own country. The famous Royal Society of England elected him as a member, but the Bolognese professors did not consider it necessary to take this into account and continued to persecute Malpighi with unremitting persistence. Even in the audience, undignified scenes were played out. One day, during a lecture, one of his opponents appeared and began to demand that the students leave the audience; Everything, they say, that Malpighi teaches is absurd, his dissections are devoid of any value, only idiots can work in this way. There was another case that was worse. Two disguised faculty professors - anatomists Muni and Sbaraglia - appeared at the scientist's country house, accompanied by a crowd of people also wearing masks. They carried out a devastating attack: Malpighi, then an old man of 61, was beaten and his household property was destroyed. This method, apparently, did not represent anything unusual in Italy of that era, since Berengario de Carpi himself once thoroughly destroyed the apartment of his scientific opponent. This was quite enough for Malpighi. He again left Bologna and went to Rome. Here he became the pope's physician and spent the rest of his life serenely.

Malpighi's discovery, dating back to 1661, could not have been made earlier, since it was impossible to examine the thinnest blood vessels, much thinner than a human hair, with the naked eye: this required a highly magnifying system of magnifying glasses, which appeared only at the beginning of the 17th century . The first microscope in its simplest form was apparently made by a combination of lenses around 1600 by Zachary Jansen of Meddelburg in Holland. Antonie van Leeuwenhoek, this genius, considered the founder of scientific microscopy, in particular microscopic anatomy, carried out microscopic studies starting in 1673 with the help of highly magnifying lenses he himself made.

In 1675, Leeuwenhoek discovered ciliates - a living world in a drop of water from a puddle. He died in 1723 at a very old age, leaving behind 419 microscopes, with which he achieved magnification up to 270 times. He never sold a single instrument. Leeuwenhoek was the first to see the transverse striation of the muscles used for movement, the first was able to accurately describe the skin scales and internal pigment deposition, as well as the mesh weave of the cardiac muscles. Already after Jan Ham, as a student in Leiden, discovered “seed lifers,” Leeuwenhoek was able to prove the presence of seed cells in all animal species.

Malpighi was the first to discover red blood cells in the blood vessels of the human mesentery, which was soon confirmed by Leeuwenhoek, but only after these cells in the blood vessels were noticed by Jan Swammerdam in 1658.

Malpighi, who should be considered an outstanding researcher in the field of natural science, finally resolved the question of blood circulation. Three spirits, which according to previous ideas were located in the blood vessels, were expelled in order to give way to a large “spirit” - a single blood moving in a vicious circle, returning to its starting point and again completing the cycle - and so on until the end of life. The forces that force the blood to complete this cycle were already clearly known.

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A special transport system that supplies cells with substances necessary for life already develops in animals with an open circulatory system (most invertebrates, as well as lower chordates); The movement of fluid (hemolymph) in these organisms is carried out due to contractions of the muscles of the body or blood vessels. Mollusks and arthropods develop a heart. In animals with a closed circulatory system (some invertebrates, all vertebrates and humans), the further evolution of blood circulation is mainly the evolution . In fish it is two-chambered. When one of the chambers, the ventricle, contracts, blood flows into the abdominal aorta, then into the vessels of the gills, then into the dorsal aorta, and from there to all organs and tissues.

Rice. 1. Diagram of the blood circulation of fish: 1 - vessels of the gills, 2 - vessels of the body, 3 - atrium, 4 - ventricle of the heart.

In amphibians, blood pumped by the ventricle of the heart into the aorta directly flows to the organs and tissues. With the transition to In addition to the main, large circle of K., a special small, or pulmonary, circle of K. appears.

Rice. 2. Diagram of the blood circulation of an amphibian: A - small circle, B - large circle; 1 - pulmonary vessels, 2 - right atrium, 3 - left atrium, 4 - ventricle of the heart, 5 - body vessels.

In birds, mammals and humans, the principle of blood circulation is the same. The blood ejected by the left ventricle into the main artery, the aorta, flows further into the arteries, then into the arterioles and capillaries of organs and tissues, where the exchange of substances between blood and tissues occurs. From tissue capillaries, venous blood flows through venules and veins to the heart, entering the right atrium. The sections of the vascular system located between the left ventricle and the right atrium make up the so-called systemic circulation.

Rice. 3. Diagram of human blood circulation: 1 - vessels of the head and neck, 2 - upper limb, 3 - aorta, 4 - pulmonary vein, 5 - vessels of the lung, 6 - stomach, 7 - spleen, 8 - intestines, 9 - lower limbs, 10 - kidneys, 11 - liver, 12 - inferior vena cava, 13 - left ventricle of the heart, 14 - right ventricle of the heart, 15 - right atrium, 16 - left atrium, 17 - pulmonary artery, 18 - superior vena cava.

From the right atrium, blood enters the right ventricle, which, when contracted, is ejected into the pulmonary artery. Then, through the arterioles, it enters the capillaries of the alveoli, where it releases carbon dioxide and is enriched with oxygen, turning from venous to arterial. Arterial blood from the lungs returns to the heart through the pulmonary veins - to its left atrium. , through which blood flows from the right ventricle to the left atrium, make up the pulmonary circulation. From the left atrium, blood flows into the left ventricle and again into the aorta.

Rice. 4. Blood circulation. Pronounced asymmetry of large arteries that appears during the development of the human embryo: 1 - right subclavian artery, 2 - pulmonary duct, 3 - ascending aorta, 4 and 8 - right and left pulmonary artery, 5 and 6 - right and left carotid artery, 7 - aortic arch, 9 - descending aorta.

The movement of blood through the vessels occurs due to the pumping function of the heart. The amount of blood ejected by the heart in 1 minute is called minute volume (MV).

Rice. 5. Blood circulation. Symmetrical formation of large arteries in the human embryo: 1 - dorsal aorta, 2 - ductus arteriosus, 3 - 8 - aortic arches.

MO can be measured directly using special flow meters. In humans, MO is determined by indirect methods. By measuring, for example, the difference in the CO 2 content in 100 ml of arterial and venous blood [(A - B) CO 2 ], as well as the amount of CO 2 released by the lungs in 1 minute (I' CO 2), the volume of blood flowing through the lungs is calculated in 1 min, - MO according to the Fick formula:

Instead of CO 2, you can determine the content of O 2 or harmless dyes, gases or other indicators specially introduced into the blood. A person’s MO at rest is 4-5 liters, and during physical or emotional stress it increases 3-5 times. Its magnitude, like the linear speed of blood flow, blood circulation time, etc., is an important indicator of the state of blood circulation. Basic data characterizing the laws of blood movement through the vessels and the state of blood in various parts of the vascular system:

Characteristics of the vascular bed and blood movement in various parts of the cardiovascular system

Notes:

* Blood volume in the cavities of the heart - 15%; blood volume in the pulmonary circle is 18%.

** Including arteries of the great circle.

The aorta and arteries of the body are a pressure reservoir in which the blood is under high pressure (normal for humans is about 120/70 mmHg). The heart pumps blood into the arteries in separate portions. At the same time, the elastic walls of the arteries are stretched. Thus, during diastole, the energy accumulated by them maintains the blood in the arteries at a certain level, which ensures the continuity of blood flow in the capillaries. The level of blood pressure in the arteries is determined by the relationship between MO and peripheral vascular resistance. The latter, in turn, depends on the tone of the arterioles, which are, in the words of the Russian scientist and materialist thinker, creator of the physiological school Ivan Mikhailovich Sechenov, “the taps of the circulatory system.” Increased arteriolar tone impedes the outflow of blood from the arteries and increases blood pressure; a decrease in their tone causes the opposite effect. In different parts of the body, arteriolar tone may change differently. With a decrease in tone in any area, the amount of blood flowing increases. In other areas, this may simultaneously result in an increase in arteriolar tone, leading to a decrease in blood flow. The total resistance of all arterioles of the body and, therefore, the value of the so-called mean arterial pressure may not change. Thus, in addition to regulating the average level of blood pressure, arteriolar tone determines the amount of blood flow through the capillaries of various organs and tissues.

The hydrostatic pressure of blood in the capillaries promotes the filtration of fluid from the capillaries into the tissue; this process is prevented by the oncotic pressure of the blood plasma.

Moving along the capillary, the blood experiences resistance, which requires energy to overcome. As a result, the blood pressure along the capillary drops. This leads to the flow of fluid from the intercellular spaces into the capillary cavity. Part of the fluid flows from the intercellular gaps through the lymphatic vessels ( click on the picture to enlarge):

Rice. 6. The pressure ratio that ensures the movement of fluid in capillaries, intercellular space and lymphatic vessels. * Negative pressure in the intercellular space, resulting from the suction of fluid by lymphatic vessels; ** the resulting pressure ensuring the movement of fluid from the capillary to the tissue; *** the resulting pressure that ensures the movement of fluid from the tissues into the capillary.

Direct measurement of fluid pressure in the intercellular spaces of tissues by introducing microcannulas connected to sensitive electromanometers showed that this pressure is not equal to atmospheric pressure, but is 5 - 10 mm Hg lower than it. Art. This seemingly paradoxical fact is explained by the fact that active pumping of fluid occurs in the tissues. Periodic compression of tissue by pulsating arteries and arterioles and contracting muscles leads to the pushing of tissue fluid into the lymphatic vessels, the valves of which prevent its return to the tissue. This creates a pump that maintains negative (relative to atmospheric) pressure in the intercellular spaces. Pumps that pump out fluid from the intercellular spaces create a constant vacuum, facilitating the continuous flow of fluid into the tissue even with significant fluctuations in capillary pressure. This ensures greater reliability of the main function of blood circulation - metabolism between blood and tissues. These same pumps simultaneously guarantee sufficient fluid outflow through the lymphatic system in cases of a sharp drop in the oncotic pressure of the blood plasma (and the resulting decrease in the reabsorption of tissue fluid into the blood). Thus, these pumps represent a true “peripheral heart”, the function of which depends on the degree of elasticity of the arteries and on the periodic activity of the muscles.

Blood flows from tissues through venules and veins. The veins of the systemic circulation contain more than half of the body's total blood. Skeletal muscle contractions and respiratory movements facilitate blood flow into the right atrium. The muscles compress the veins located between them, squeezing blood towards the heart (reverse blood flow is impossible due to the presence of valves in the veins:

Rice. 7. The action of skeletal muscles, helping the movement of blood through the veins: A - muscle at rest; B - when it contracts, blood is pushed upward through the vein - to the heart; the lower valve prevents the reverse flow of blood; B - after the muscle relaxes, the vein expands, filling with a new portion of blood; the upper valve prevents its reverse flow; 1 - muscle; 2 - valves; 3 - vein.

The increase in negative pressure in the chest during each breath helps draw blood to the heart. The blood circulation of individual organs - the heart, lungs, brain, spleen - differs in a number of features due to the specific functions of these organs.

Coronary circulation also has significant features.

Rice. 8. Diagram of the blood circulation of a human embryo: 1 - umbilical cord, 2 - umbilical vein, 3 - heart, 4 - aorta, 5 - superior vena cava, 6 - cerebral veins, 7 - cerebral arteries, 8 - aortic arch, 9 - ductus arteriosus , 10 - pulmonary artery, 11 - inferior vena cava, 12 - descending aorta, 13 - umbilical arteries.

Regulation of blood circulation

The intensity of activity of various organs and tissues is constantly changing, and therefore their need for various substances also changes. At a constant level of blood flow, the delivery of oxygen and glucose to tissues can triple due to more complete utilization of these substances from the flowing blood. Under the same conditions, the delivery of fatty acids can increase by 28 times, amino acids by 36 times, carbon dioxide by 25 times, protein metabolic products by 480 times, etc. Consequently, the most “bottleneck” of the circulatory system is the transport of oxygen and glucose. Therefore, if the amount of blood flow is sufficient to provide tissues with oxygen and glucose, it is more than sufficient for the transport of all other substances. In tissues, as a rule, there are significant reserves of glucose deposited in the form of glycogen; oxygen reserves are practically absent (with the exception of only very small amounts of oxygen bound to muscle myoglobin). Therefore, the main factor determining the intensity of blood flow in tissues is their need for oxygen. The work of the mechanisms regulating K. is aimed primarily at satisfying precisely this need.

In the complex system of blood circulation regulation, only general principles have so far been studied and only some links have been studied in detail. Significant progress in this area has been achieved, in particular, thanks to the study of the regulation of the main function of the cardiovascular system - blood circulation - using methods of mathematical and electrical modeling. K. is regulated by reflex and humoral mechanisms that provide organs and tissues at any given moment with the amount of oxygen they need, as well as the simultaneous maintenance of the basic parameters of hemodynamics - blood pressure, MO, peripheral resistance, etc. - at the required level.

The processes of blood regulation are carried out by changes in the tone of arterioles and the value of MO. The tone of the arterioles is regulated by the vasomotor center located in the medulla oblongata. This center sends impulses to the smooth muscles of the vascular wall through the centers of the autonomic nervous system. The required blood pressure in the arterial system is maintained only under the condition of constant tonic contraction of the muscles of the arterioles, which requires the continuous supply of nerve impulses to these muscles through the vasoconstrictor fibers of the sympathetic nervous system. These pulses follow at a frequency of 1-2 pulses per 1 second. An increase in frequency leads to an increase in arteriolar tone and an increase in blood pressure; a decrease in impulses causes the opposite effect. The activity of the vasomotor center is regulated by signals coming from baroreceptors or mechanoreceptors of vascular reflexogenic zones (the most important of them is the carotid sinus). An increase in pressure in these areas causes an increase in the frequency of impulses arising in the baroreceptors. which leads to a decrease in the tone of the vasomotor center, and consequently to a decrease in response impulses coming from it to the smooth muscles of the arterioles. This leads to a decrease in the tone of the muscle wall of the arterioles, a decrease in heart rate (decreased MO) and, as a consequence, a drop in blood pressure. A drop in pressure in these areas causes the opposite reaction:

Rice. 9. Diagram of one of the links in the mechanism of blood pressure regulation.

Thus, the entire system is a servomechanism that works on the feedback principle and maintains blood pressure at a relatively constant level (see depressor reflexes, carotid reflexes). Similar reactions occur when baroreceptors in the pulmonary circulation are stimulated. The tone of the vasomotor center also depends on impulses arising in the chemoreceptors of the vascular bed and tissues, as well as under the influence of biologically active substances in the blood. In addition, the state of the vasomotor center is also determined by signals coming from other parts of the central nervous system. Thanks to this, adequate changes in blood circulation occur when the functional state of any organ, system or the whole organism changes.

In addition to the tone of the arterioles, there is also a value of MO, which depends on the amount of blood flowing to the heart and on the energy of heart contractions. The amount of blood flowing to the heart depends on the tone of the smooth muscles of the venous wall, which determines the capacity of the venous system, on the contractile activity of skeletal muscles, which facilitates the return of blood to the heart, as well as on the total volume of blood and tissue fluid in the body. The tone of the veins and the contractile activity of skeletal muscles are determined by impulses arriving to these organs, respectively, from the vasomotor center and the centers that control body movement. The total volume of blood and tissue fluid is regulated by reflexes that occur in the stretch receptors of the right and left atria. An increase in blood flow to the right atrium excites these receptors, causing a reflex inhibition of the adrenal glands' production of the hormone Aldosterone. A deficiency in aldosterone leads to increased excretion of Na and Cl ions in the urine and, as a result, to a decrease in the total amount of water in the blood and tissue fluid, and consequently to a decrease in the volume of circulating blood. Increased stretching of the left atrium by blood also causes a decrease in the volume of circulating blood and tissue fluid. However, in this case, another mechanism is activated: signals from stretch receptors inhibit the release of the hormone vasopressin by the pituitary gland, which leads to increased release of water. The magnitude of MO also depends on the strength of contractions of the heart muscle, which is regulated by a number of intracardiac mechanisms, the action of humoral agents, and the central nervous system.

In addition to the described central mechanisms of blood circulation regulation, there are also peripheral mechanisms. One of them is changes in the “basal tone” of the vascular wall, which occur even after the complete shutdown of all central vasomotor influences. Stretching of the vascular walls with an excess amount of blood causes, after a short period of time, a decrease in the tone of the smooth muscles of the vascular wall and an increase in the volume of the vascular bed. Decreasing blood volume has the opposite effect. Thus, a change in the “basal tone” of blood vessels ensures, within certain limits, the automatic maintenance of the so-called average pressure in the cardiovascular system, which plays an important role in the regulation of cardiac output. The reasons for direct changes in the “basal tone” of blood vessels have not yet been sufficiently studied.

So, the general regulation of blood cells is ensured by complex and diverse mechanisms, often duplicating each other, which determines the high reliability of regulation of the general state of this most important system for the body.

Along with the general mechanisms of blood circulation, there are central and local mechanisms that control local blood circulation, that is, blood circulation in individual organs and tissues. Studies using microelectrode technology, studying the vascular tone of certain areas of the body (resistography) and other works have shown that the vasomotor center selectively includes neurons that regulate the tone of certain vascular areas. This allows you to reduce the tone of some vascular areas, while simultaneously increasing the tone of others. Local dilation of blood vessels occurs not only as a result of a decrease in the frequency of vasoconstrictor impulses, but in some cases as a result of signals arriving through special vasodilator fibers. A number of organs are supplied with vasodilator fibers of the parasympathetic nervous system, and skeletal muscles are innervated by vasodilator fibers of the sympathetic system. Vasodilation of any organ or tissue occurs when the working activity of this organ increases and is not always accompanied by general changes in blood circulation. Peripheral mechanisms of blood circulation regulation ensure an increase in blood flow through the organ or tissue with an increase in their working activity. It is believed that the main reason for these reactions is the accumulation in tissues of metabolic products that have a local vasodilator effect (this opinion is not shared by all researchers). Biologically active substances play a significant role in the general and local regulation of blood. These include hormones - adrenaline, renin and, possibly, vasopressin and the so-called local, or tissue, hormones - serotonin, bradykinin and other kinins, prostaglandins and other substances. Their role in the regulation of K. is being studied.

The circulatory regulation system is not closed. It continuously receives information from other parts of the central nervous system and, in particular, from the centers that regulate body movements, the centers that determine the occurrence of emotional stress, and from the cerebral cortex. Thanks to this, changes in K. occur with any changes in the state and activity of the body, with emotions, etc. These changes in K. are adaptive, adaptive in nature. The restructuring of the K. function often precedes the transition of the body to a new regime, as if preparing it in advance for the upcoming activity.

Circulatory disorders

Circulatory disorders can be local and general in nature. Local - manifested by arterial and venous hyperemia or caused by disturbances in the nervous regulation of blood vessels, embolism, as well as the effect of external damaging factors on the vessels; local violations of K. underlie endarteritis obliterans and others.

General disorders are manifested by circulatory failure - a condition in which the circulatory system does not deliver the required amount of blood to organs and tissues. A distinction is made between cardiac insufficiency of cardiac (central) origin if its cause is a dysfunction of the heart; vascular (peripheral) - if the cause is associated with primary disorders of vascular tone; general With K., venous stagnation is noted, since less blood is thrown into the arteries than flows to it through the veins. Vascular insufficiency is characterized by a decrease in venous and blood pressure: the venous flow to the heart decreases due to a discrepancy between the capacity of the vascular bed and the volume of blood circulating in it. Its causes may be those causing the development of heart failure: hypoxia and tissue metabolic disorders. Congestive failure is characterized by myocardial hypertrophy, increased venous pressure, increased mass of circulating blood, edema, and slowed blood circulation. In case of deficiency associated with primary , 1927;

History of the discovery of the role of the heart and circulatory system

This drop of blood that appeared
then disappearing again, it seemed,
hesitated between existence and the abyss,
and this was the source of life.
She's red! She is beating. This is the heart!

W. Harvey

A look into the past

Doctors and anatomists of ancient times were interested in the work of the heart and its structure. This is confirmed by information about the structure of the heart given in ancient manuscripts.

In the Ebers papyrus* “The Secret Book of the Physician” there are sections “Heart” and “Vessels of the Heart”.

Hippocrates (460–377 BC), the great Greek physician, who is called the father of medicine, wrote about the muscular structure of the heart.

Greek scientist Aristotle(384–322 BC) argued that the most important organ of the human body is the heart, which is formed in the fetus before other organs. Based on observations of death occurring after cardiac arrest, he concluded that the heart is the thinking center. He pointed out that the heart contains air (the so-called “pneuma” - a mysterious carrier of mental processes that penetrates matter and animates it), spreading through the arteries. Aristotle assigned the brain a secondary role as an organ designed to produce fluid that cools the heart.

The theories and teachings of Aristotle found followers among representatives of the Alexandrian school, from which many famous doctors of Ancient Greece emerged, in particular Erasistratus, who described the heart valves, their purpose, as well as the contraction of the heart muscle.

Ancient Roman doctor Claudius Galen(131–201 BC) proved that blood flows in arteries, not air. But Galen found blood in the arteries only in living animals. The dead's arteries were always empty. Based on these observations, he created a theory according to which blood originates in the liver and is distributed through the vena cava to the lower part of the body. Blood moves through the vessels in tides: back and forth. The upper parts of the body receive blood from the right atrium. There is a communication between the right and left ventricles through the walls: in the book “On the Purpose of Parts of the Human Body,” he provided information about the oval hole in the heart. Galen made his “mite to the treasury of prejudices” in the doctrine of blood circulation. Like Aristotle, he believed that the blood is endowed with “pneuma.”

According to Galen's theory, arteries do not play any role in the work of the heart. However, his undoubted merit was the discovery of the fundamentals of the structure and functioning of the nervous system. He was the first to indicate that the brain and spinal column are the sources of activity of the nervous system. Contrary to the statement of Aristotle and representatives of his school, he argued that “the human brain is the abode of thought and the refuge of the soul.”

The authority of ancient scientists was undeniable. To encroach on the laws they established was considered sacrilege. If Galen argued that blood flows from the right side of the heart to the left, then this was accepted as true, although there was no evidence for this. However, progress in science cannot be stopped. The flourishing of sciences and arts during the Renaissance led to a revision of established truths.

An outstanding scientist and artist also made an important contribution to the study of the structure of the heart. Leonardo da Vinci(1452–1519). He was interested in the anatomy of the human body and was going to write a multi-volume illustrated work on its structure, but, unfortunately, he did not finish it. However, Leonardo left behind records of many years of systematic research, providing them with 800 anatomical sketches with detailed explanations. In particular, he identified four chambers in the heart, described the atrioventricular valves (atrioventricular), their chordae tendineae and papillary muscles.

Of the many outstanding scientists of the Renaissance, it is necessary to highlight Andreas Vesalius(1514–1564), a talented anatomist and fighter for progressive ideas in science. Studying the internal structure of the human body, Vesalius established many new facts, boldly contrasting them with erroneous views that were rooted in science and had a centuries-old tradition. He outlined his discoveries in the book “On the Structure of the Human Body” (1543), which contains a thorough description of the anatomical sections performed, the structure of the heart, as well as his lectures. Vesalius refuted the views of Galen and his other predecessors on the structure of the human heart and the mechanism of blood circulation. He was interested not only in the structure of human organs, but also in their functions, and paid most attention to the work of the heart and brain.

Vesalius's great merit lies in the liberation of anatomy from the religious prejudices that bound it, medieval scholasticism - a religious philosophy according to which all scientific research must obey religion and blindly follow the works of Aristotle and other ancient scientists.

Renaldo Colombo(1509(1511)–1553) - a student of Vesalius - believed that blood from the right atrium of the heart enters the left.

Andrea Cesalpino(1519–1603) - also one of the outstanding scientists of the Renaissance, doctor, botanist, philosopher, proposed his own theory of human blood circulation. In his book “Peripathic Discourses” (1571), he gave a correct description of the pulmonary circulation. It can be said that he, and not William Harvey (1578–1657), the outstanding English scientist and physician who made the greatest contribution to the study of the work of the heart, should have the glory of discovering blood circulation, and Harvey’s merit lies in the development of Cesalpino’s theory and its proof by relevant experiments.

By the time Harvey appeared on the “arena,” the famous professor at the University of Padua Fabricius Acquapendente I found special valves in the veins. However, he did not answer the question of what they are needed for. Harvey set about solving this mystery of nature.

The young doctor performed his first experiment on himself. He bandaged his own hand and waited. Only a few minutes passed, and the hand began to swell, the veins swollen and turned blue, and the skin began to darken.

Harvey guessed that the bandage was holding back the blood. But which one? There has been no answer yet. He decided to conduct experiments on a dog. Having lured a street dog into the house with a piece of pie, he deftly threw the string around his paw, wrapped it around it and pulled it off. The paw began to swell and swell below the bandaged area. Having again lured the trusting dog, Harvey grabbed his other paw, which also turned out to be tightened in a tight noose. A few minutes later Harvey called the dog again. The unfortunate animal, hoping for help, hobbled for the third time to its tormentor, who made a deep cut on his paw.

The swollen vein below the bandage was cut and thick, dark blood dripped from it. On the second paw, the doctor made an incision just above the bandage, and not a single drop of blood flowed out. With these experiments, Harvey proved that blood in the veins moves in one direction.

Over time, Harvey compiled a circulatory diagram based on the results of sections performed on 40 different species of animals. He came to the conclusion that the heart is a muscular sac that acts as a pump, forcing blood into the blood vessels. Valves allow blood to flow in only one direction. Heart beats are successive contractions of the muscles of its parts, i.e. external signs of the “pump” operation.

Harvey came to a completely new conclusion that the blood flow passes through the arteries and returns to the heart through the veins, i.e. In the body, blood moves in a vicious circle. In a large circle it moves from the center (heart) to the head, to the surface of the body and to all its organs. In the small circle, blood moves between the heart and lungs. In the lungs, the composition of the blood changes. But how? Harvey didn't know. There is no air in the vessels. The microscope had not yet been invented, so he could not trace the path of blood in the capillaries, just as he could not figure out how the arteries and veins were connected to each other.

Thus, Harvey is responsible for the proof that the blood in the human body continuously circulates (circulates) always in the same direction and that the central point of blood circulation is the heart. Consequently, Harvey refuted Galen's theory that the center of blood circulation was the liver.

In 1628, Harvey published a treatise “An Anatomical Study of the Movement of the Heart and Blood in Animals,” in the preface of which he wrote: “What I present is so new that I fear that people will not be my enemies, for once accepted prejudices and teachings are deeply rooted in everyone.”

In his book, Harvey accurately described the work of the heart, as well as the small and large circles of blood circulation, and indicated that during the contraction of the heart, blood from the left ventricle enters the aorta, and from there, through vessels of smaller and smaller cross-sections, it reaches all corners of the body. Harvey proved that “the heart beats rhythmically as long as there is life in the body.” After each contraction of the heart, there is a pause in the work, during which this important organ rests. True, Harvey could not determine why blood circulation is needed: for nutrition or for cooling the body?

William Harvey tells Charles I
about blood circulation in animals

The scientist dedicated his work to the king, comparing it to the heart: “The king is the heart of the country.” But this little trick did not save Harvey from the attacks of scientists. Only later was the scientist’s work appreciated. Harvey's merit also lies in the fact that he guessed about the coexistence of capillaries and, having collected scattered information, created a holistic, truly scientific theory of blood circulation.

In the 17th century events occurred in the natural sciences that radically changed many previous ideas. One of them was the invention of the microscope by Antoni van Leeuwenhoek. The microscope allowed scientists to see the microcosm and the subtle structure of the organs of plants and animals. Leeuwenhoek himself, using a microscope, discovered microorganisms and the cell nucleus in the red blood cells of the frog (1680).

The last point in solving the mystery of the circulatory system was put by an Italian doctor Marcello Malpighi(1628–1694). It all started with his participation in meetings of anatomists in the house of Professor Borely, at which not only scientific debates and readings of reports took place, but also animal dissections were performed. At one of these meetings, Malpighi opened up a dog and showed the structure of the heart to the ladies of the court and gentlemen who attended these meetings.

Duke Ferdinand, interested in these questions, asked to dissect a living dog to see how the heart worked. The request was fulfilled. In the open chest of the Italian greyhound, the heart was beating rhythmically. The atrium contracted and a sharp wave ran through the ventricle, lifting its blunt end. Contractions were also visible in the thick aorta. Malpighi accompanied the autopsy with explanations: from the left atrium, blood enters the left ventricle..., from it passes into the aorta..., from the aorta into the body. One of the ladies asked: “How does blood get into the veins?” There was no answer.

Malpighi was destined to unravel the last mystery of the blood circulation. And he did it! The scientist began research, starting with the lungs. He took a glass tube, attached it to the cat’s bronchi and began to blow into it. But no matter how much Malpighi blew, the air did not leave his lungs. How does it get from the lungs into the blood? The issue remained unresolved.

The scientist pours mercury into the lung, hoping that with its heaviness it will break into the blood vessels. The mercury stretched the lung, a crack appeared on it, and shiny droplets rolled down the table. “There is no communication between the respiratory tubes and blood vessels,” Malpighi concluded.

Now he began to study arteries and veins using a microscope. Malpighi was the first to use a microscope in studies of blood circulation. At 180x magnification, he saw what Harvey could not see. Examining a specimen of a frog's lungs under a microscope, he noticed air bubbles surrounded by a film and small blood vessels, an extensive network of capillary vessels connecting arteries to veins.

Malpighi not only answered the lady of the court's question, but completed the work begun by Harvey. The scientist categorically rejected Galen’s theory of blood cooling, but he himself made the wrong conclusion about the mixing of blood in the lungs. In 1661, Malpighi published the results of observations on the structure of the lung, and for the first time gave a description of capillary vessels.

The last point in the doctrine of capillaries was put by our compatriot, anatomist Alexander Mikhailovich Shumlyansky(1748–1795). He proved that arterial capillaries directly pass into certain “intermediate spaces,” as Malpighi believed, and that the vessels are closed along their entire length.

An Italian researcher was the first to report on lymphatic vessels and their connection with blood vessels. Gaspard Azeli (1581–1626).

In subsequent years, anatomists discovered a number of formations. Eustachius discovered a special valve at the mouth of the inferior vena cava, L.Bartello– duct connecting the left pulmonary artery with the aortic arch in the prenatal period, Lower- fibrous rings and intervenous tubercle in the right atrium, Tebesius - the smallest veins and the valve of the coronary sinus, Vyusan wrote a valuable work on the structure of the heart.

In 1845 Purkinje published research on specific muscle fibers that conduct excitation through the heart (Purkinje fibers), which laid the foundation for the study of its conduction system. V.Gis in 1893 he described the atrioventricular bundle, L.Ashoff in 1906 together with Tawaroi– atrioventricular (atrioventricular) node, A.Kis in 1907 together with Flex described the sinoatrial node, Yu. Tandmer At the beginning of the 20th century, he conducted research on the anatomy of the heart.

Domestic scientists have made a great contribution to the study of heart innervation. F.T. Bider in 1852 he discovered clusters of nerve cells (Bider's node) in the frog's heart. A.S. Dogel in 1897–1890 published the results of studies of the structure of the nerve ganglia of the heart and the nerve endings in it. V.P. Vorobiev in 1923 he conducted classic studies of the nerve plexuses of the heart. B.I. Lavrentiev studied the sensitivity of the innervation of the heart.

Serious research into the physiology of the heart began two centuries after W. Harvey's discovery of the pumping function of the heart. The most important role was played by the creation K. Ludwig kymograph and his development of a method for graphically recording physiological processes.

An important discovery of the influence of the vagus nerve on the heart was made by the brothers Webers in 1848. This was followed by the discoveries of the brothers Tsionami sympathetic nerve and study of its effect on the heart I.P. Pavlov, identification of the humoral mechanism of transmission of nerve impulses to the heart O. Levi in 1921

All these discoveries made it possible to create a modern theory of the structure of the heart and blood circulation.

Heart

The heart is a powerful muscular organ located in the chest between the lungs and the sternum. The walls of the heart are formed by a muscle unique to the heart. The heart muscle contracts and is innervated autonomously and is not subject to fatigue. The heart is surrounded by the pericardium - the pericardial sac (cone-shaped sac). The outer layer of the pericardium consists of inextensible white fibrous tissue, the inner layer consists of two layers: visceral (from lat. viscera– viscera, i.e. related to internal organs) and parietal (from lat. parietalis- wall, wall).

The visceral layer is fused with the heart, the parietal layer is fused with fibrous tissue. Pericardial fluid is released into the gap between the layers, reducing friction between the walls of the heart and surrounding tissues. It should be noted that the generally inelastic pericardium prevents excessive stretching of the heart and its overflow with blood.

The heart consists of four chambers: two upper ones - thin-walled atria - and two lower ones - thick-walled ventricles. The right half of the heart is completely separated from the left.

The function of the atria is to collect and hold blood for a short time until it passes into the ventricles. The distance from the atria to the ventricles is very short, therefore the atria do not need to contract with great force.

The right atrium receives deoxygenated (oxygen-poor) blood from the systemic circulation, and the left atrium receives oxygenated blood from the lungs.

The muscular walls of the left ventricle are approximately three times thicker than the walls of the right ventricle. This difference is explained by the fact that the right ventricle supplies blood only to the pulmonary (lesser) circulation, while the left ventricle pumps blood through the systemic (large) circle, which supplies blood to the entire body. Accordingly, the blood entering the aorta from the left ventricle is under significantly higher pressure (~105 mm Hg) than the blood entering the pulmonary artery (16 mm Hg).

When the atria contract, blood is pushed into the ventricles. There is a contraction of the circular muscles located at the confluence of the pulmonary and vena cava into the atria and blocking the mouths of the veins. As a result, blood cannot flow back into the veins.

The left atrium is separated from the left ventricle by the bicuspid valve, and the right atrium from the right ventricle by the tricuspid valve.

Strong tendon threads are attached to the valve flaps from the ventricles, the other end is attached to the cone-shaped papillary (papillary) muscles - outgrowths of the inner wall of the ventricles. When the atria contract, the valves open. When the ventricles contract, the valve leaflets close tightly, preventing blood from returning to the atria. At the same time, the papillary muscles contract, stretching the tendon threads, preventing the valves from everting towards the atria.

At the bases of the pulmonary artery and aorta there are connective tissue pockets - semilunar valves, which allow blood to pass into these vessels and prevent it from returning to the heart.

To be continued

* Found and published in 1873 by German Egyptologist and writer Georg Maurice Ebers. Contains about 700 magical formulas and folk recipes for treating various diseases, as well as getting rid of flies, rats, scorpions, etc. The papyrus describes the circulatory system with amazing accuracy.

Ancient and Renaissance scientists had very unique ideas about movement, the meaning of the heart, blood and blood vessels. For example, Galen says: “Parts of food absorbed from the digestive canal are carried by the portal vein to the liver and, under the influence of this large organ, are converted into blood. Blood, thus enriched with food, endows these same organs with nutritional properties, which are summarized in the expression “natural spirits,” but blood endowed with these properties is still unprocessed, unsuitable for the higher purposes of blood in the body. Brought from the liver through v. cava to the right half of the heart, some parts of it pass from the right ventricle through countless invisible pores to the left ventricle. When the heart expands, it draws air from the lungs through a vein-like artery, the “pulmonary vein,” into the left ventricle, and in this left cavity the blood that has passed through the septum is mixed with the air thus sucked there. With the help of that warmth that is innate to the heart, placed here as a source of body warmth by God at the beginning of life and remaining here until death, it is saturated with further qualities, loaded with “vital spirits” and then is already adapted to its external duties. The air thus pumped into the left heart through the pulmonary vein, at the same time softens the innate warmth of the heart and prevents it from becoming excessive.”

Vesalius writes about blood circulation: “Just as the right ventricle sucks blood from the v. cava, the left ventricle pumps into itself air from the lungs every time the heart relaxes through the venous artery, and uses it to cool the innate heat, to nourish its substance and to prepare vital spirits, generating and purifying this air so that it, together with the blood which leaks in enormous quantities through the septum from the right ventricle to the left may be destined for the great artery (aorta) and thus for the whole body.”

Miguel Servet (1509-1553). His burning is depicted in the background.

The study of historical materials indicates that the pulmonary circulation was discovered by several scientists independently of each other. The first to discover the pulmonary circulation in the 12th century was the Arab physician Ibn al-Nafiz from Damascus, the second was Miguel Servet (1509-1553) - lawyer, astronomer, metrologist, geographer, physician and theologian. He listened to lectures by Silvius and Gunther in Padua and may have met Vesalius. He was a skilled physician and anatomist, since his belief was the knowledge of God through the structure of man. V.N. Ternovsky assessed the unusual direction of Servetus’s theological teaching as follows: “Knowing the spirit of God, he had to know the spirit of man, know the structure and work of the body in which the spirit lives. This forced him to conduct anatomical research and geological work.” Servetus published the books “On the Errors of the Trinity” (1531) and “The Restoration of Christianity” (1533). The last book was burned by the Inquisition, as was its author. Only a few copies of this book have survived. In it, among theological considerations, the pulmonary circulation is described: “... in order, however, for us to understand that the blood becomes living (arterial), we must first study the emergence in the substance of the vital spirit itself, which is composed and nourished from inhaled air and very thin blood. This vital air arises in the left ventricle of the heart, the lungs being especially helpful in its improvement; it is a subtle spirit generated by the power of heat, yellow (light) color, igniting power, so that it appears as if it were a radiating vapor from the purer blood containing the substance of water, air with the generated paired blood, and which passes from right ventricle to left. This passage, however, does not take place, as is usually thought, through the medial wall (septum) of the heart, but in a remarkable manner the delicate blood is driven along a long path through the lungs.”

William Harvey (1578-1657)

William Harvey (1578-1657), an English physician, physiologist and experimental anatomist, who truly understood the importance of the heart and blood vessels, who in his scientific work was guided by the facts obtained in experiments. After 17 years of experimentation, Harvey published a small book in 1628, “An Anatomical Study of the Movement of the Heart and Blood in Animals,” where he pointed out the movement of blood in a large and small circle. The work was deeply revolutionary in the science of that time. Harvey was unable to show small vessels connecting the vessels of the systemic and pulmonary circulation, however, the prerequisites were created for their discovery. From the moment of Harvey's discovery, true scientific physiology begins. Although scientists of that time were divided into adherents of Gachen and Harvey, ultimately Harvey's teachings became generally accepted. After the invention of the microscope, Marcello Malpighi (1628-1694) described the blood capillaries in the lungs and thereby proved that the arteries and veins of the systemic and pulmonary circulation are connected by capillaries.

Harvey's thoughts on blood circulation influenced Descartes, who hypothesized that processes in the central nervous system are automatic and do not constitute the human soul.

Descartes believed that nerve “tubes” diverge radially from the brain (like blood vessels from the heart), automatically carrying reflections to the muscles.

Pre-Harvey circulatory studies

It can be considered generally accepted that the doctrine of blood circulation is a product of European natural science of the New Age and that we owe the creation of this harmonious system of physiological ideas to W. Harvey. Harvey's discovery of blood circulation (1628) is understood by most historians, physiologists, and clinicians as a milestone with which scientific physiology in general and the physiology of blood circulation in particular began. Arguments in favor of this point of view can be built as follows. The subject of Harvey's research was precisely blood circulation, that is, the movement of blood through a closed system, including two isolated circulatory circles. Each conclusion was based on experimental observations and mathematical calculations, the most important tools of new, experimental knowledge. The system of evidence as a whole, the very style of scientific thinking testified to the similarity of the methodological attitudes of the author and his contemporary Francis Bacon. What we have here is not a guess of a brilliant mind and not a harmonious hypothesis that needs fundamental proof. We have before us a consistently and carefully developed research program, which later became the basis for the study of physiology and then the pathology of the cardiovascular system. Both the research methodology and the facts themselves, ascertained and clarified by Harvey, are included without any reservations in the modern doctrine of blood circulation. In this sense, the entire previous period can be considered as the pre-Harvey era of the initial accumulation of knowledge about the movement of blood through the vessels.

Borelli taught that muscle contraction depends on the swelling of cells due to the penetration of blood and spirits; the latter travel along the nerves voluntarily or involuntarily; as soon as the spirits meet the blood, an explosion occurs and a contraction appears. The blood restores the organs, and the nervous spirit maintains their vital properties.

According to Hoffmann, life consists of blood circulation and the movement of other fluids; it is supported by blood and spirits, and through separations and secretions it balances the functions and protects the body from putrefaction and deterioration. Blood circulation is the cause of heat, all strength, muscle tension, inclinations, qualities, character, intelligence and madness; The cause of blood circulation should be considered the narrowing and expansion of solid particles, which occurs due to the very complex composition of the blood. Heart contractions are caused by the influence of nerve fluid developing in the brain.

Claudius Galen

Claudius Galen was quite close to the discovery of blood circulation. He examined in detail the mechanism of breathing, and the work of muscles, lungs and nerves was sequentially analyzed; He considered the purpose of breathing to weaken the warmth of the heart. The main place where blood is located was recognized as the liver. Nutrition according to Galen consists of borrowing the necessary particles from the blood and removing unnecessary ones; Each organ secretes a special fluid.

Claudius Galen and all his followers believed that the bulk of the blood is contained in the veins and communicates through the ventricles of the heart, as well as through openings (“anastomoses”) in the vessels passing nearby. Despite the fact that all attempts by anatomists to find the holes in the septum of the heart indicated by Galen were in vain, Galen's authority was so great that his statement was usually not questioned. The Arab physician Ibn al-Nafiz (1210-1288) from Damascus, the Spanish physician M. Servetus, A. Vesalius, R. Colombo and others only partially corrected the shortcomings of Galen’s scheme, but the true meaning of the pulmonary circulation remained unclear until Harvey.

Miguel Servet

The first person to have such a thought was Miguel Servet, a Spanish doctor who was burned for Arianism in Geneva about 140 years ago. He gave a description of the pulmonary circulation, thus refuting Galen's theory about the passage of blood from the left half of the heart to the right through small holes in the atrial septum.

Miguel Servetus was born in 1511 in Spain. He studied law and geography, first in Zaragoza, then in France, in Toulouse. For some time after graduating from university, Servetus served as secretary to the confessor of Emperor Charles V. While at the imperial court, he lived for a long time in Germany, where he met Martin Luther. This acquaintance aroused Servetus' interest in theology. Although Servetus was self-taught in this area, he nevertheless studied theology deeply enough that he did not agree with the teachings of the church fathers in everything.

Yielding to the persuasion of his friend, the court physician of the Prince of Lorraine, Servet thoroughly studied medicine in Paris. His teachers were, like Vesalius, Silvius and Gunther. Contemporaries said that it is hardly possible to find an equal to Servetus in knowledge of the teachings of Galen. Even among learned anatomists, Servetus was known as an excellent expert in anatomy. Servetus became the house physician of the Archbishop of Vienna, in whose palace he spent twelve quiet years, working on solving certain issues of medicine and faith.

In a book entitled The Restoration of Christianity, published in 1553, he clearly states that blood passes through the lungs from the left to the right ventricle of the heart, and not through the septum separating the two ventricles, as was believed at that time. So, chronologically, the first description of the pulmonary circulation in Europe appears in a work devoted not to medical, but to theological problems. “The Restoration of Christianity” is the most complete expression of the anti-trinitarian views of Servetus, very inaccurately defined by W. Wotton as “Arianism.” At first glance, the question of the movement of blood seems to be a “foreign body” artificially placed in a theological treatise. But upon careful examination, one gets the impression that the idea of ​​blood circulation in Servetus’ text is natural and organic.

Chapter 5 of “The Restoration of Christianity” talks about the Holy Spirit, which, according to Servetus, is not a hypostasis of the Trinity, but a form of manifestation of God, a connecting link between God and man. From the concept of the Spirit, Servetus moves on to the concept of the soul, relying on those provisions in the Old Testament where it is said that the soul is in the blood. For him, logically there is a need to give some idea about blood, its purpose as the abode of the soul and its movement in the body. Here we meet the formulation of the thesis about pulmonary circulation. Servetus tries to fit this thesis into the general picture of the world, which includes the idea of ​​God and man.

The version about the unconditional priority of Servetus in the discovery of pulmonary circulation lasted for more than 200 years. But in 1924, a manuscript by the Arab physician Ibn al-Nafis, “Commentary to the Treatise of Ibn Sina,” dating back to the 2nd half of the 13th century, was discovered in Damascus, and this manuscript contained a clearly formulated statement about the movement of blood from the right half of the heart through lungs to his left half. Servetus did not know about the existence of the text of Ibn al-Nafis and came to the discovery of the pulmonary circulation on his own.

Realdo Colombo

A few years after Servetus, Vesalius's student Realdo Colombo, coming up with a similar hypothesis, based it on more rigorous scientific evidence. The pulmonary circulation was opened a second time. At the same time, the works of Colombo and other researchers of that time organically fit into the foundation of physiological knowledge created by Harvey.

Colombo was born in 1516 in Cremona and studied in Venice and Padua. In 1540, he was appointed professor of surgery in Padua, but then this department was transferred to Vesalius, and Colombo was appointed his assistant. He was then invited to be a professor of anatomy in Pisa, and two years later Pope Paul IV appointed him a professor of anatomy in Rome, where he worked until the end of his life. Colombo's work "On Anatomy", where thoughts about the pulmonary circulation were expressed, was published in the year of his death.

William Harvey was familiar with Colombo's idea of ​​the pulmonary circulation, absolutely identical to Servetus's; he himself writes about it in his work on the movement of the heart and blood. No one can say whether Harvey knew about Servetus’ work. Almost all copies of the book Restoring Christianity were burned.

Andrea Caesalpin

Another predecessor of Harvey is the Italian Andrea Caesalpina (1519-1603), professor of anatomy and botany in Pisa, physician to Pope Clement VIII. In his books “Questions of the Doctrine of the Peripatetics” and “Medical Questions,” Caesalpinus, like Servetus and Colombo, described the transition of blood from the right half of the heart to the left through the lungs, but did not abandon Galen’s teaching about the leakage of blood through the septum of the heart. Caesalpinus was the first to use the expression “blood circulation,” but did not put into it the concept that was later given by Harvey.

Harvey's discovery

The Englishman Harvey clarified the question of the movement of blood in the body. This was a huge task for his time. But his predecessors had already moved away from the classical misconception that blood vessels are air tubes. All that remained was to trace the entire path of the blood and establish that the entire body was permeated with tubes that did not end anywhere, passing into one another, representing a completely closed system. To do this, it was necessary to trace a particle of blood along its entire path.

Harvey did it and did it this way. He ligated blood vessels in various parts and looked at what happened to the contents of the vessels above and below the ligation site. So gradually he determined the movement of blood.

Opening of blood circulation

William Harvey came to the conclusion that a snake bite is dangerous only because the venom spreads through the vein from the site of the bite throughout the body. For English doctors, this insight became the starting point for reflection that led to the development of intravenous injections. It is possible, the doctors reasoned, to inject this or that medicine into a vein and thereby introduce it into the entire body. But German doctors took the next step in this direction by using a new surgical enema on humans (as intravenous injection was then called). The first injection experience was made by one of the most prominent surgeons of the second half of the 17th century, Mateus Gottfried Purman from Silesia. Czech scientist Pravac proposed an injection syringe. Before this, syringes were primitive, made from pig bladders, with wooden or copper spouts embedded in them. The first injection was performed in 1853 by English doctors.

After arriving from Padua, simultaneously with his practical medical activities, Harvey conducted systematic experimental studies of the structure and function of the heart and blood flow in animals. He first presented his thoughts in another Lumley lecture, which he gave in London on April 16, 1618, when he already had a large amount of observational and experimental material. Harvey briefly formulated his views by saying that blood moves in a circle. More precisely, in two circles: small - through the lungs and large - through the whole body. His theory was incomprehensible to listeners, it was so revolutionary, unusual and alien to traditional ideas. Harvey's Anatomical Inquiry into the Movement of the Heart and Blood in Animals appeared in 1628 and was published in Frankfurt am Main. In this study, Harvey refuted Galen's teaching about the movement of blood in the body, which had prevailed for 1500 years, and formulated new ideas about blood circulation.

Of great importance for Harvey's research was the detailed description of the venous valves that direct the movement of blood to the heart, first given by his teacher Fabricius in 1574. The simplest and at the same time the most convincing proof of the existence of blood circulation, proposed by Harvey, was to calculate the amount of blood passing through the heart. Harvey showed that in half an hour the heart ejects an amount of blood equal to the weight of the animal. Such a large amount of moving blood can only be explained based on the concept of a closed circulatory system. Obviously, Galen's assumption about the continuous destruction of blood flowing to the periphery of the body could not be reconciled with this fact. Harvey received another proof of the fallacy of his views about the destruction of blood on the periphery of the body in his experiments of applying a bandage to the upper limbs of a person. These experiments showed that blood flows from arteries to veins. Harvey's research revealed the importance of the pulmonary circulation and established that the heart is a muscular sac equipped with valves, the contractions of which act as a pump forcing blood into the circulatory system.

Opponents of Harvey's discovery

Having refuted Galen's ideas, Harvey was criticized by contemporary scientists and the church. Opponents of the theory of blood circulation in England called its author the name “circulator”, which was offensive to a doctor. This Latin word translates as “wandering medicine man”, “charlatan”. They also called all supporters of the doctrine of blood circulation circulators. It is noteworthy that the Paris Medical Faculty also refused to recognize the fact of blood circulation in the human body. And this is 20 years after the discovery of blood circulation.

Jean Riolan

The fight against Harvey was led by Jean Riolan son. In 1648, Riolan published the work “Manual of Anatomy and Pathology,” in which he criticized the doctrine of blood circulation. He did not reject it as a whole, but expressed so many objections that, in essence, he crossed out Harvey's discovery. Riolan personally sent his book to Harvey. The main feature of Riolan as a scientist was conservatism. He knew Harvey personally. As physician to Marie de' Medici, the French dowager queen, mother of Henrietta Maria, wife of Charles I, Riolan came to London and lived there for some time. Harvey, as the king's personal physician, when visiting the palace, met with Riolan, demonstrated his experiments to him, but could not convince his Parisian colleague of anything.

Riolan's father was the head of all anatomists of his time. He, like his son, bore the name Jean. Father Riolan was born in 1539, in the village of Montdidier near Amiens, and studied in Paris. In 1574 he received the degree of doctor of medicine and in the same year the title of professor of anatomy. Then he was dean of the Paris Faculty of Medicine (in 1586-1587). Riolan the father was a famous scientist: in addition to medicine, he taught philosophy and foreign languages, left many works on metaphysics and the works of Hippocrates and Fernel; outlined the doctrine of fevers in “Tractatus de febribus” (1640). He died in 1605.

Jean Riolan son was born, studied and received his doctorate in medicine in Paris. Since 1613, he headed the department of anatomy and botany at the University of Paris, and was physician to Henry IV and Louis XIII. The fact that, as the first physician to Henry IV's wife Marie de' Medici, he followed the disgraced queen into exile, treated her for varicose veins and remained with her until her death, enduring countless hardships, speaks volumes about his spiritual qualities.

Riolan the son was an excellent anatomist. His main work, “Anthropographie” (1618), wonderfully describes human anatomy. He founded the "Royal Garden of Medicinal Herbs", a scientific institution, conceived in 1594 by Henry IV. Under the pseudonym Antarretus he wrote a number of polemical articles against Harvey. Through the efforts of this magnificent scientist, the outstanding physician Harvey was slandered at the faculty: “He who allows blood to circulate in the body has a weak mind.”

Guy Paten

A devoted student of Riolan the son of Guy Patin, one of the luminaries of the then medicine, the physician of Louis XIV, wrote about Harvey’s discovery: “We are living through an era of incredible inventions, and I don’t even know whether our descendants will believe in the possibility of such madness.” He called Harvey's discovery “paradoxical, useless, false, impossible, incomprehensible, absurd, harmful to human life,” etc.

Patan's parents prepared him to become a lawyer, and at worst they agreed to become a priest, but he chose literature, philosophy and medicine. In his immense zeal as an orthodox follower of Galen and Avicenna, he was very distrustful of the new means used in medicine in his time. Paten's reactionary attitude may not seem so wild if we remember how many victims the craze for antimonial drugs brought about. On the other hand, he welcomed bloodletting. Even infancy did not save from this dangerous procedure. “Not a day passes in Paris,” writes Patin, “when we do not prescribe bleeding from infants.”

“If medicines do not cure, then death comes to the rescue.” This is a typical reflection of the era when the satire of Molière and Boileau ridiculed scholastic doctors who, as they aptly put it, stood with their backs to the patient and their faces to the “holy scriptures.” For his conservatism that knows no bounds, Moliere ridiculed Guy Patin in “Malade imaginoire” (“The Imaginary Invalid”), showing him in the person of Doctor Diafuarus.

For a long time, the Paris Faculty of Medicine was a hotbed of conservatism; it consolidated the authority of Galen and Avicenna by parliamentary decree, and deprived doctors who adhered to the new therapy of practice. The Faculty in 1667 banned blood transfusions from one person to another. When the king supported this saving innovation, the faculty went to court and won the case.

Harvey found defenders. The first among them was Descartes, who spoke out in favor of blood circulation, and thereby greatly contributed to the triumph of Harvey’s ideas.

In 1654, Harvey was unanimously elected president of the London College of Medicine, but declined the position for health reasons.

If Vesalius laid the foundations of modern human anatomy, Harvey created a new science - physiology, a science that studies the function of human and animal organs. I. P. Pavlov called Harvey the father of physiology. He said that the doctor William Harvey spied on one of the most important functions of the body - blood circulation and thereby laid the foundation for a new department of precise knowledge - animal physiology.

Circulation studies after Harvey

Harvey did not know about the existence of capillaries, which he designated as “tissue pores.” He could not see them without a microscope, and the assumption of their existence was a brilliant guess based on correct premises. In 1661, after Harvey's death, capillaries were discovered by Malpighi. After Malpighi's discovery there could no longer be any doubt about the correctness of Harvey's views, which had previously been disputed.

Malpighi, using a microscope, studies the development of the chicken, blood circulation in the smallest vessels, the structure of the tongue, glands, liver, kidneys, and skin. Ruysch became famous for his excellent fillings (injections) of vessels, which made it possible to see vessels where they were previously unsuspected. Over the course of 50 years, Leeuwenhoek found many new facts in the study of all tissues and parts of the human body; discovered blood cells and seminal filaments (spermatozoa).

The next important event in the study of blood circulation was the determination of arterial blood pressure. This was done by measuring the height to which the blood rises in a vertically reinforced glass tube connected to the lumen of the horse's carotid artery (Gels experiment, 1732).

Intensive development of the physiology of blood circulation began only in the 40s of the last century. Since that time, graphic recording of processes occurring in the circulatory system began to be used; The amount of blood in the body was measured, and the importance of various physical factors involved in the movement of blood was studied. At the same time, the study of the regulation of blood circulation began.

An important study that established the existence of nervous influences on the activity of the circulatory system was the work carried out in 1842 in Kyiv by N. I. Pirogov’s student, Walter. He proved that stimulation of the “sympathetic threads” contained in the sciatic nerve of the frog leads to a narrowing of the blood vessels of the leg. Then the inhibitory effect of the anticipatory nerve on the heart was established (Weber brothers, 1845): an increase in heart rate was shown when sympathetic nerve fibers were excited (Pezold, Zion); the influence of various nerves on blood vessels was studied in detail (Claude Bernard); reflex changes in blood circulation were discovered. naturally occurring in response to irritation of afferent fibers coming from the aortic receptors (I. F. Iipn and K. Ludwig). V. Ovsyannikov accurately established that certain areas of the medulla oblongata contain nerve formations, the destruction of which disrupts the reflex regulation of the sogus. At about the same time, N. O. Kovalevsky, M. Traube and others proved that blood circulation changes when carbon dioxide accumulates in the blood.

Thus, for the period 1840-1880. a number of important individual facts characterizing the physical processes occurring in the circulatory system were described in detail, the influence exerted on the heart and blood vessels by nerve fibers approaching them, and changes in blood circulation that reflexively occur during “painful” irritation, bloodletting, asphyxia (suffocation) and other effects on the body. These works revealed some processes that play an important role in the regulation of blood circulation, but could not provide clear ideas about the mechanisms that determine the normal functioning of the circulatory system under normal living conditions.

I. P. Pavlov

For the first time I.P. Pavlov in 1880-1890. with his systematically conducted experiments, he indicated ways to study the normal regulation of blood circulation, showing that the regulation of blood circulation can be studied under conditions of chronic experiment on healthy, non-anesthetized animals. It was in these animals that he established a significant constancy of arterial blood pressure and found that it was maintained due to the constantly ongoing regulatory influence of the central nervous system, leading to the redistribution of blood.

By introducing the technique of “cold cutting” (reversible shutdown by cooling) of the vagus nerve, Pavlov showed the importance of nervous influences in maintaining a relatively constant level of blood pressure.

I.P. Pavlov did not at all belittle the importance of vivisection experiments - his study of the amplifying nerve of the heart is an example of research of this kind. He saw, however, in acute experiments only a means for isolating (analyzing) the role of various factors involved in a particular complex phenomenon, and never forgot that the vivisection technique as such is associated with a disruption of the animal’s normal connections with the environment.

Back in 1882, Pavlov raised in all its breadth the question of the importance of the regulation of blood circulation in maintaining the relative constancy of blood pressure. He wrote about this: “The enormous importance of an accurate study of the devices that guard this desire for constancy is immeasurable.”

After Ludwig, Zion and Pavlov, the physiological mechanisms that ensure the constancy of blood pressure began to be studied in detail again only in the 20s of our century. At the same time, however, foreign researchers focused only on reflexes from two groups of receptors of the vascular system, namely from the endings of the aortic nerve discovered by Zion and Ludwig and from the receptors of the branching region of the common carotid artery discovered about 30 years ago. Meanwhile, Pavlov emphasized back in the 80s that the regulation of blood circulation is carried out due to the action of various stimuli “... on the peripheral endings of the centripetal nerves,” i.e., receptors contained in all organs and all tissues. The irritation of these receptors constitutes, as Pavlov wrote, “the starting point of the reflex,” which “... in the life of a complex organism... is the most significant and most frequent nervous phenomenon.” In particular, all normal regulation of blood circulation is based on reflexes. Thus, I.P. Pavlov 60-70 years ago indicated ways to study the normal regulation of blood circulation as reflex acts arising from various receptors.

Clinical studies have been and are of significant importance in the study of blood circulation. The clinic allows you to study in humans changes in blood circulation caused by one or another damage to the heart, blood vessels, nervous system, etc. The needs of the clinic led to the development of methods for determining blood pressure in the arteries and veins of a person, the amount of blood ejected by the heart. Many works have been carried out to study fluctuations in blood pressure and pulse rate, as well as venous pressure, blood flow speed and the amount of blood ejected by the heart per minute in various diseases and different conditions of the body. Many studies are devoted to the so-called functional diagnostics of the cardiovascular system, the study of the causes and consequences of a long-term increase in blood pressure (hypertension) and its sharp drop (with shock, collapse, blood loss), the study of the mechanism of vascular spasms and blockage of blood vessels, the analysis of changes in heart activity by studying electrical phenomena in it, etc.