August Krogh

Schack August Steenberg Krogh, just when August Krogh known (* November 15, 1874 in Grenaa ( Djursland ); † September 13, 1949 in Copenhagen) was a Danish physician and zoologist. For the discovery of kapillarmotorischen regulatory mechanism in 1920 he received the Nobel Prize for Medicine.

Life and work

Early years and education

August Krogh was born in 1874 in the city Grenaa in Jutland, Denmark. His parents were Viggo Krogh, a shipwright, and Marie Krogh, was born Drechmann. He was very interested already during his school days in the natural sciences and conducted simple experiments with animals and plants. Strongly influenced him was his teacher William Sorensen, who showed him the physiology experiments. In 1893 he began studying medicine at the University of Copenhagen, but moved very quickly to zoology, which was more to him.

Around 1896 he worked as a student with the hydrostatic mechanism of Corethra larvae, a genus of clump mosquitoes, whose larvae live in water and on - and stay on changes in their density. He noted that these larvae have gas bubbles in the body that could be filled as needed with oxygen from the surrounding water. Published his results until 1911.

In 1897 he got a job in the laboratory of Christian Bohr, where he focused on medical physiology and after graduation was Bohr's assistant. He examined here the gas exchange of living organisms and has been honored by the publication of an article about the release of gaseous nitrogen through the body with the blessing Prize, an award from the Austrian Academy of Sciences.

In 1902 he interrupted his studies for a research trip to Greenland, where he grappled with a physically - lacustrine issues. So he studied the tensions into carbonic acid and the oxygen content in the water of source streams and the sea. The role of the sea for the oxygen content in the atmosphere was an important research area, on which he published several important publications.

His doctorate in 1903 on the basis of a study on the gas exchange of frogs. Here he was able to demonstrate that the cutaneous respiration of the animals was very constant during the portion of the gas, which is absorbed through the lungs, has fluctuated widely and is controlled by the control of the vagus nerve. After graduation, he studied the diet of the Inuit in Greenland and the impact of their very one-sided, based only on meat diet on their body. In 1905 he married the medical student Birte Marie Jorgensen, 1914 also received his doctorate. Her doctoral thesis dealt with the gas exchange, but in humans. Together with her he had four children, three daughters. Marie died in 1943.

Research on the gas exchange in the lung

In 1908 August Krogh was an assistant professor of Animal Physiology at the University of Copenhagen, which was created especially for him in 1916 and converted into a full professorship. This chair Krogh kept until his retirement in 1945. Yet even then he continued to work in his private laboratories in Gjenstofte that were put to him by the Scandinavian Insulin Foundation.

At the very beginning of his professorship rejected Krogh his first hypothesis that gas exchange is an active additional form of gas uptake in the lungs. Instead, he put together with his wife, a completely new theory of gas absorption on and was able to confirm this as well. With the help of the developed by him Mikrotonometers he was able to prove in 1910 that the oxygen pressure in the alveoli, the alveoli, always higher than in the surrounding blood vessels, causing the gas exchange between the lungs and blood is solely due to a diffusion process. He disagreed with the work of his colleague and former laboratory director Christian Bohr and the theories of John Burdon Sanderson Haldane, who were at the time favored theses. Through the work of many other researchers his hypotheses have been confirmed and are now recognized and explored doctrine.

His other works focus on the binding and transport of oxygen in the blood and the gas exchange between blood and the surrounding tissue. So he was able to influence the carbon dioxide pressure on the capacity of the hemoglobin for oxygen by the blood, together with Christian Bohr and Charles Albert Hasselbalch. Together with the influence of capture carbon dioxide by oxygen shown by Haldane so could a conclusive explanation for the gas composition of the blood are found.

The Kapillarmotorische regulatory mechanism

Together with Johannes Lindhard explored August Krogh a more general question of the blood flow in order to find an explanation for the massive increase in demand in the work of muscles. To accomplish this had the blood flow, especially of the venous blood have a high variability at rest and he could not be sufficient to completely fill the ventricle. This showed the experiments, which were confirmed by these theories.

Another important result was a more accurate analysis of increasing blood and oxygen flow to the muscles during exercise. Since the oxygen pressure in a resting muscle was small could always the sufficient increase of the oxygen supply can only be explained by an increase of the surface to which an oxygen exchange is possible. On this fundamental concept built on the following research by Krogh, which led to an understanding of the involvement of the blood capillaries in muscle, for which he was awarded the Nobel Prize in 1920. Here he was able to show that the capillary network of the muscles only then fills with blood when the muscle is active. He explored this process called " kapillarmotorischen regulatory mechanism " and has both the activation of the capillary blood flow as well as the regulation clarify.

After the Nobel Prize, he continued his research continues in this area and published it in 1922 in his book The Anatomy and Physiology of the Capillaries and in other publications. He expanded his work to include other areas of the complex, such as the thermal regulation, the influence of diet and the capacity of muscle power, the formation of lactic acid in the muscle training and muscle fatigue as well as the connection with the activity of the kidneys.

Further work

In addition to the work detailed above shown above the gas exchange busy August Krogh many other questions of physiology. He pointed both in insects and in vertebrates by a large influence of the outside temperature, which he explained on the Arrhenius equation. Also external influences on the development of the animals he was able to prove. His work on gas exchange expanded Krogh on the Tracheenatmung of insects. He showed that here also the absorption of oxygen by diffusion only. For the disposal of carbon dioxide it hypothesized that this is delivered through the body surface and does not enter into the trachea, as measured here, the concentration of carbon dioxide is very small. For the increased oxygen consumption when flying through the flight muscles Krogh was able to demonstrate a ventilation mechanism by a slight contraction of the trachea.

For the breakdown of body fat for muscle work Krogh showed a loss of 11% from carbohydrates, which he explained with the conversion of fat to carbohydrates. Another focus of his work group was to investigate the water absorption and the exchange of ions in living cells.

Honors

In addition to the Nobel Prize for Medicine and Physiology August Krogh received a number of other awards for his work. So he became an honorary doctorates from the universities in Edinburgh, Budapest, Lund, Harvard, Göttingen, Oslo and Oxford. In 1916 he became a member of the Academy of Sciences in Denmark in 1937 by the Royal Society in London and the German Academy of Sciences Leopoldina. In the same year he was awarded the Baly Medal of the Royal College of Physicians in London.