Who is the British doctor who discovered blood circulation?

For a long time, human beings have been full of all kinds of magical ideas about blood. Blood is regarded as a symbol of life and vitality. Scholars have been studying it since ancient India and ancient Greece. However, people have always believed Galen's theory. Galen suggested that food nutrition flows from the intestine to the liver, where it becomes venous blood, then flows to the right side of the heart through the vein, then flows to the left side from the small hole of the heart diaphragm, meets fresh air from the lungs, becomes bright red arterial blood, and then is sent to the whole body from the artery. The flow of blood in the body rushes forward like a tide and finally disappears around the body. Since the Renaissance, scholars have questioned Galen's theory. Leonardo da vinci observed that the human heart has four chambers, not two as Galen said; Vesaliua found that there was no hole in the heart as Galen said. However, none of them can shake Galen's theory of blood flow and tide. Servit, a contemporary Spanish doctor and scholar of Vesaliua, was also a man who didn't believe in authority. Through dissection, he found that blood flowed from the right ventricle into the lungs, and after air purification, bright red blood flowed from the lungs into the left atrium. In fact, this is the pulmonary circulation. Servit was close to discovering blood circulation, but he was burned alive by the church because his views betrayed religion. He is 42 years old. His works, except a few manuscripts, have been reduced to ashes. Servit gave his life for science and truth. Blood circulation was finally discovered by Harvey, a famous British doctor and physiologist. Harvey was born in a peasant family in England. He has been diligent and studious since childhood. 16 years old was admitted to Cambridge University with excellent results, 19 years old received a bachelor's degree in literature, and 24 years old received a doctor's degree in medicine. In order to solve the mystery of blood flow, Harvey did a lot of autopsies, especially animal vivisection experiments, and made careful observation and research. Harvey found that cold-blooded animals such as snakes are good materials for heart experiments. Their heartbeat is very slow, and they can keep beating for a while when exposed to the outside world. He observed that when the heart contracts, it turns white and blood is squeezed out of the heart, but when the heart expands, it turns red and blood enters the heart again. He concluded that the heart is like a pump, which is the power source of blood flow. Harvey did many experiments, trying to measure the exact amount of blood pumped by each heartbeat. He found that even a rough calculation can prove that the heart pumps so much blood. The human heart beats about 72 times per minute and 4320 times per hour. Assuming that the heart can hold 2 ounces of blood, the heart can send 8,640 ounces of blood into blood vessels in one hour, 1 ounce equals 28.35g, and 8,640 ounces equals 244,944g, which means that the heart can deliver nearly 245kg of blood in one hour. It is impossible for the body to produce and consume blood at such a fast speed. The logical explanation is that blood circulates in the body. To prove the direction of blood flow, Harvey did a very simple experiment. He tied human upper limbs or animal bodies with ropes. The arterial tube between each ligation and the heart will bulge with the beating of the heart, while the vein will not. This shows that arterial blood flows from the heart to all parts of the body, while venous blood flows towards the heart. He found that each half of the human heart is divided into two chambers, which are separated by a valve that can only pass in one direction, so blood can only flow in one direction, but not in the opposite direction. According to these experiments, Harvey put forward the theory of blood circulation. Venous blood enters the right ventricle from the right atrium, and then enters the lungs, where it turns into bright red blood and then flows back to the left ventricle, then flows from the left ventricle into arterial blood vessels and flows to the whole body, and then flows back to the right atrium through veins, and the cycle is endless. 1682, Harvey published his monograph on blood circulation, The Theory of Heart-Blood Movement, which, like Vesaliua's Human Body Structure, has also been severely criticized by conservatives headed by the church for more than ten years. But the fact is unstoppable. Engels spoke highly of Harvey's achievements and pointed out that "Harvey established physiology as a science because he discovered blood circulation". However, Harvey's theory also left an unsolved mystery, that is, how does blood return from artery to vein? Harvey guessed that there must be an invisible vascular network between arteries and veins. As there was no microscope at that time, this hypothesis could not be confirmed. Four years after Harvey's death, the mystery was finally solved by Italian doctor Marby. He observed the capillaries in frog's lungs with a microscope, and confirmed that besides arteries and veins, there are countless tiny blood vessels invisible to the naked eye. It is these tiny blood vessels that connect arteries and veins into a sealed pipeline, making blood flow around.