What has been documented about the study of blood?

The understanding of blood by early 19th-century medical scientists was little different from that of ancient Greek medical scientists more than 2,000 years earlier. Although as early as the 17th century, scholars had described a change in the color of venous blood from dark to light when it came into contact with air and had experimentally demonstrated that a certain gas was involved in life support, it was not until 100 years later that scientists were sure what this gas involved in life support was.In the second half of the 18th century, the English chemist Priestley isolated oxygen. Unsure of his discovery, he told his friend, the famous French scientist Lavoisier, about it. Lavoisier immediately recognized its importance and began experimenting with respiration, combustion and oxygen. By 1777, he had created a chemical theory that considered life to be an oxidizing process. But the French revolution ended their work, and Priestley was exiled to America after his church was sacked, while Lavoisier was guillotined.

Despite the fact that Priestley and Lavoisier were not able to complete their work, there was no break in the scientific study of oxygen and blood. This vast scientific subject began at the end of the 18th century and continued into the 20th century. 1851 saw the discovery of hemoglobin by the German physiologist Funk, and soon after another German scientist, Hopper Sailer, demonstrated that hemoglobin carries and releases oxygen. The greatest contribution to the study of hemoglobin function is the Danish scientist Bohr's work on oxygen transport, who mathematically expressed the relationship between oxygen and hemoglobin, the famous S-shaped oxygen departure curve. The oxygen departure curve he proposed describes a remarkable property of blood - its changeable affinity for oxygen. The Bohr family has a tradition of excellent scientific research. His son, Niels Bohr, and grandson, Ager Bohr, won the 1922 and 1975 Nobel Prizes in Physics, respectively.

By the end of the 19th century, many of the important functions of blood were gradually being recognized by medical scientists. The realization of these functions was closely related to the development of chemical analysis of blood. It has already been mentioned that in the 19th century medical men made great progress in the study of the cellular constituents of blood, but little was known about the other constituents of blood. In fact, at that time, there were already some medical scientists began to pay attention to the changes in the chemical composition of the blood in normal and abnormal conditions, for example, Roger Tansky, André, Magendie and Bernard, etc. have noticed that the tissue cells of the organism in the absence of anatomical changes before the body has shown signs of disease, and therefore speculated that these lesions may be related to the changes in the chemical composition of the blood. The concept of "milieuintemal" (internal environment) proposed by the famous French medical doctor Bernard emphasized the important role of blood in regulating the stability of the "internal environment". However, due to the limitations of testing methods, they could only do simple semi-quantitative studies, such as blood glucose; uric acid testing, and did not understand most of the components of the blood.

It was not until the beginning of the 20th century, with the development of analytical chemistry and the invention of various measuring instruments, that the various metabolites in the blood became known. Medical scientists who have made outstanding contributions in this field include Flynn, Bunn and Slaughter. Wu Xian, a medical scientist in China, had made important improvements to Flynn's method of blood glucose analysis, and later people called their analysis method Flynn a Wu method.