Schack August Steenberg Krogh, briefly as August Krogh admits, (* 15 November 1874 in Grenaa, "† 13 September 1949 in Copenhagen) was a Danish physician and zoologist. For the discovery of the capillary-motor regularization mechanism it received the Nobelpreis for medicine to 1920.

Life and work

Early years and training

August Krogh was born 1874 in the city Greena on Jutland in Denmark. Its parents were Viggo Krogh, a ship farmer, and Marie Krogh, born Drechmann. It was interested already during its school time very much in the natural sciences and accomplished simple experiments with animals and plants. Strongly its teacher William which pointed him experiments to the physiology, affected it. 1893 it began its study of the medicine at the university in Copenhagen, changed however very fast to the Zoologie, which was appropriate for it more.

Over 1896 it itself as a student with the hydrostatic mechanism of the Corethra larvae, a kind of bundle mosquitoes, whose larvae in the water live and ascend and descend over changes of their density. It stated that these larvae have gas bubbles in the body, which could be filled if necessary with oxygen from the surrounding water. Its results only 1911 were published.

1897 he got a place in the laboratory of Christian bores, where it became with medical physiology busy and after its exam Bohrs assistant. It examined here the gas exchange of living organisms and by the publication of an article over the delivery by gaseous nitrogen by the body with the sea-gene price, an honor of the Austrian Academy of Sciences, was honoured.

In the year 1902 it interrupted its studies for a Forschungsreise to Greenland, where it argued with physical limnischen questions. Thus it studied the stress ratios in carbonic acid and the oxygen content in the water of source, brooks and the sea. Also the role of the sea for the oxygen household of the atmosphere was an important Forschungsgebiet, over which it published several important publications.

Its graduation took place 1903 on the basis of an investigation for the gas exchange of the frogs. Here it could prove that the skin respiration of the animals was very constant during the portion of the gas, which is taken up over the lungs, very strongly varied and by control of the Nervus vagus is controlled. After the graduation it studied the nutrition of the Inuit in Greenland and the effects of its very one-sided, only nutrition which is based on meat on their body. 1905 he married the medicine student Birte Marie which likewise attained a doctorate to 1914. Also its graduation topic busy itself with the gas exchange, however with humans. Together with their it had four children, of it three daughters. 1943 died Marie.

Research over the gas exchange in the lung

In the year 1908 August Krogh received a Asistenzprofessur for animal physiology at the university in Kopenhangen, which was created specially for it and 1916 were converted into a tidy Professur. Krogh up to its retirement kept this chair in the year 1945. But even after it it continued to work in its private laboratories in Gjenstofte, which were put to it by the Scandinavian insulin Foundation at the disposal.

Equal to beginning of its professor activity Krogh rejected its first hypothesis that the gas exchange was in the lungs an active additional form of the gas admission. Instead it set up a completely new theory of the gas admission together with its wife and could these also confirm. With the help of the Mikrotonometers developed by him it could prove 1910 that the oxygen pressure in the alveoli, which is ever higher alveoles, than in the blood vessels surrounding them, whereby the gas exchange between lung and blood is to be led exclusive on Diffusionsvorgang back. Thus it contradicted the work of his colleague and former laboratory leader Christian bores and the theories of John Burdon Sanderson Haldane, which applied at the time as favourisierte theses. By the work many further researcher was confirmed its hypotheses however and is today recognized and investigated Lehrmeinung.

Its further work was concerned with the connection and the transport of the oxygen in the blood as well as the gas exchange of the blood with the surrounding fabric. Thus it knew Karl Albert Hasselbalch the influence of the carbon dioxide pressure on the photograph capacity that together with Christian bores and hemoglobin for oxygen by the blood. Together with the influence of the admission for carbon dioxide by oxygen, represented by Haldane, so a conclusive explanation for the gas composition of the blood could be found.

The capillary-motor regularization mechanism

Together with Johannes Lindhard investigated August Krogh a further general question of the blood river, around an explanation for the substantial increase of the need with the work of the musculature. In order to manage this had the blood river above all the venous blood a high variability to exhibit and in dwell phases could it not be sufficient, in order to fill the heart ventricle completely. The experiments could show this, whereby these theories were confirmed.

A further important result was a more exact analysis of the increase of the blood and oxygen throughput in the musculature during the manipulation. Since the oxygen pressure was always in a resting muscle shr small could the sufficient increase of the oxygen supply only by an enlargement of the surface is explained, at which an oxygen exchange is possible. On this basic consideration the following research of Krogh develops, which led to an understanding of the praying hurrying of the blood capillaries in the musculature and were distinguished for which it with the Nobelpreis 1920. Here it could show that the capillary net of the musculature fills only then with blood if the muscle is active. He investigated as "capillary-motor regularization mechanism" designated procedure for these and could both the activation of the capillary blood river and the regularization up clear.

After the Nobelpreis it continued its research at this Geniet and published it 1922 in its book "The Anatomy and Physiology OF the Capillaries" as well as in further publications. It expanded its work also on other ranges of the complex, for instance the heat regularization, the influence of the nutrition as well as the capacity of the muscle achievement, the formation of lactic acid in the muscle, training and muscle fatigue as well as the connection with the kidney activity.

Further work

Beside above in detail represented work over the gas exchange employed August Krogh many further questions of the physiology. It proved both with insects and with vertebrate animals a large influence of the outside temperature, which it explained over the Arrhenius equation. Also it could prove external influences on the development of the animals. Also Krogh expanded its work to the gas exchange on the trachea respiration of the insects. It proved that the admission of oxygen takes place also here exclusively via diffusion. For the delivery carbon dioxide it set up the hypothesis that this is not delivered over the unf into the tracheae arrived, since the concentration at carbon dioxide, measured here, is only very small. For the increased rushing first off only with flies by the flight musculature Krogh could a ventilation mechanism by an easy contraction of the tracheae prove.

For the dismantling of body fat for the muscle work Krogh proved a loss of 11% opposite coal hydrates, which he explained with the change of the fat as coal hydrates. A further emphasis of its working group was the study of the water absorption and the exchange of ions with living cells.

Honours

Beside the Nobelpreis for medicine and physiology August Krogh received a number of further honors for its work. Thus he became an honour doctor of the universities in Edinburgh, Budapest, Lund, Harvard, Goettingen, Oslo and Oxford. 1916 it became member of the Academy OF Sciences in Denmark 1937 the Royal Society in London. In the same year it received the Baly medal of the Royal college OF Physicians in London.

Literature

• Bernhard Kupfer: Encyclopedia of the , Patmos publishing house Duesseldorf 2001, ISBN 3491724511

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