Krogh August

November 15, 1874, Mr.. - September 13, 1949
Shek Danish physiologist August Krogh Steenburgen was born in Grenaa (Jutland peninsula), the family shipbuilder, the brewer and publisher of the newspaper Viggo Krogh and Marie Krogh (Drehman), whose ancestors were gypsies. Since an early age to. interested in natural sciences and spent much time studying insects around your home. When K. was about 14 years, he left school, and dreaming to become a naval officer, joined the Danish navy ship, protecting fisheries, Iceland. This service generated the. lifelong love of the sea and ships. A year later he began to study at the cathedral school in Aarhus, and in 1893. enrolled in the University of Copenhagen, to study physics and medicine.
Under the influence of the zoologist William Sorensen K. larvae began to explore the kind of organism Corethra, aquatic. He found that their bladder is functioning like plunging the submarine. In the interests of K. also had a great influence lectures Christian Bohr (father of physicist Niels Bohr), the well-known authority on the physiology of blood and respiration. In 1897. K. began work under the guidance of Bohr in the laboratory of medical physiology. Two years later, K. Master of Science degree in zoology at the University of Copenhagen and was appointed assistant to Bora.
For research Corethra K. mikrotonometr invented - a device to measure the partial pressure or tension, the gas dissolved in the liquid (eg, oxygen in the blood). In 1902, during sea expeditions to Greenland, to. measured the oxygen and carbon dioxide in the marine and fresh water and improved method of tonometric measurement of dissolved gases. This work provided new understanding of the ocean's role in the regulation of carbon dioxide in the atmosphere.
In the next year to. received his doctorate in zoology at the University of Copenhagen for his thesis on lung and skin breathing frogs. Respiration - is the exchange of oxygen and carbon dioxide between cells and the environment. K. found that the frog skin respiration is relatively constant, and the lung - changes and is regulated by the vagus nerve, related to the vegetative (autonomous) nervous system. At the time of breathing oxygen passes into the capillaries of the lungs through the pulmonary membrane vesicles - alveoli. More oxygen is carried to the tissues of the body and in the oxidation process turns into carbon dioxide. In turn, carbon dioxide passes from the blood into the alveoli and the lungs removed from the body.
When K. began to study the mechanism of respiration was still unclear and was a discussion between representatives of the two concepts. According to one of them, the cells alveolar-capillary membrane actively secrete the respiratory gases in one direction or another. Proponents of the opposite point of view argued that the gases diffuse through the membrane passively. Bohr, who believed that the lungs function like cancer, took a first concept. Nevertheless, with the help mikrotonometra for measuring the partial pressure of oxygen and carbon dioxide in the lungs and blood,. and his colleagues have shown that gas exchange in the lungs is carried out only by diffusion. In addition, K. Bohr described the effect of different concentrations of carbon dioxide in the blood of oxyhemoglobin dissociation curve (a phenomenon known as the Bohr effect).
In 1905, Mr.. K. married Mary Jorgensen, also worked as a physiologist in the laboratory of Bohr. Their son became a dissector at the department of anatomy at the University of Aarhus, two daughters - dentists, and the youngest daughter - a physiologist in the United States.
A year after his marriage to. Siegen was awarded the Prize of the Austrian Academy of Sciences for his work in which he showed that gaseous nitrogen is not involved in normal metabolic processes in animals. His international reputation grew further when, in 1907. at the International Congress of Physiologists in Heidelberg (Germany), he presented the work on the diffusion of gases in the lungs.
In 1908, Mr.. specifically for K. University of Copenhagen was established as Adjunct Professor of Zoology. In the same year, he and his wife went into the second expedition to Greenland to study the effects of a diet consisting almost exclusively of meat, on metabolism and respiration Eskimos. Two years later, University of Copenhagen gave K. physiological laboratory in Ny-Vestergeyde, in which the couple continued their collaboration.
Together with Johannes Lindgaard, who later became a professor of the theory of gymnastics, K. determined cardiac output at rest and during muscular load. For this he used the method to determine the velocity of blood flow in the lungs with nitrogen oxide. The researchers found that the number of arterial blood flowing from the left heart, depends on the number of venous blood coming in to the right departments.
In 1916, Mr.. K. was appointed Professor of Zoology, University of Copenhagen. In a series of studies he examined the physiological regulation of capillary blood flow (and hence oxygen delivery to tissues and cells). Capillaries - small blood vessels is the diameter of the order of several microns, which are the continuation of precapillary arterioles and postcapillary venules in passing. In contrast to the arteries and veins, whose walls are composed of several layers, the capillaries have a wall of one layer of cells. Through these walls are exchanged between the blood and tissues of oxygen, carbon dioxide, nutrients and other substances. In previous studies of the capillaries of muscles under the binocular microscope revealed that the capillaries 'open' and 'closed' is not synchronous, ie. not in the rhythm of fluctuations in blood pressure. In addition, it was already known that any increase in blood flow due to increased blood pressure and increases capillary blood flow.
. Having concluded that the surface area of 'open', or functioning, capillaries (capillary diffusion surface) should directly depend on the oxygen consumption, K
. showed that the number of functioning capillaries in turn, is regulated by local mechanical, chemical and temperature factors. In experiments conducted in the language of the frogs, he found that if the work of the muscles language capillaries are clearly visible and are filled with blood, the rest are empty and become invisible. Subsequently, one of the students Krogh, Bevolf Vimtrup, said that the 'discovery' and 'closure' of the capillaries is controlled by the contractile elements contained in specialized cells of Rouget capillary wall. Research to. gas exchange in the lungs and the regulation of capillary blood flow were the basis of respiratory intubation and application of hypothermia in open heart surgery.
In 1920, Mr.. K. was awarded the Nobel Prize in Physiology or Medicine "for his discovery of the mechanism of regulation of the lumen of the capillaries'. K. showed that at rest is open only part of the capillaries, whereas in the work of their number increases in accordance with the consumption of oxygen. Proof By. that this mechanism operates in all organs and tissues, is of great importance for modern science. In his Nobel lecture to. examined the physiology of the capillaries on the basis of data obtained in experiments on frogs.
During a visit to the United States in 1922. read Sillimanovskih lectures at Yale University to. studied insulin, open the year before, Frederick G. Banting and John dP. Macleod. Due to the fact that his wife to. suffered from diabetes, insulin is particularly interested in him, and he made a great contribution to the organization in Denmark laboratories for the study and production of insulin. Later K. investigated the permeability of cell membranes for water and salts, the differences in breathing during the flight in insects, and studied the history of science. He was keenly interested in issues of sociobiology bees and wrote articles on the works of Karl von Frisch on the development of communication links in honey bees.
When the Nazi army occupied Denmark, K., an outspoken opponent of Nazism, he moved to Sweden. Back in 1945. home, he began work on his chair at Copenhagen University and continued his studies in the laboratory, provided to him and Carlsberg Scandinavian insulin funds. K. written numerous popular science books and he was a passionate bibliophile, he is particularly fond of novels of Rudyard Kipling. K. died in Copenhagen on 13 September 1949
In English physiologist Archibald. Hill wrote of K.: 'Krogh was a great experimenter and inventive creator of scientific instruments, but his experience and love for the beautiful techniques never obscured for him the fundamental scientific problems. "
To. been awarded many prizes, t. h. Bailey medals to the Royal Society of Physicians (1945), honorary degrees from Edinburgh, Budapest, Gottingen, Harvard, Ratgerovskogo, Oxford University, as well as the universities of Lund and Oslo. He was a foreign member of the London Royal Society and many other scientific societies.