On November 15, 1874, Danish zoophysiologist August Krogh was born. Krogh contributed a number of fundamental discoveries within several fields of physiology, and is famous for developing the Krogh Principle, which states that “for such a large number of problems there will be some animal of choice, or a few such animals, on which it can be most conveniently studied.” In 1920 August Krogh was awarded the Nobel Prize in Physiology or Medicine for the discovery of the mechanism of regulation of the capillaries in skeletal muscle.
August Krogh was born on the peninsula of Jutland in Denmark. He attended the University of Copenhagen and earned his doctorate degree in 1903. Krogh wrote his thesis on the through the skin and lungs in frogs, entitled Respiratory Exchange of Animals. Already in 1897 he began to work in the Laboratory of Medical Physiology under the Professor Christian Bohr. After completing his examination in zoology, Krogh became Bohr’s assistant. In 1908, he started teaching at the University of Copenhagen and was promoted to full Professor becoming the head of the first laboratory for animal physiology in 1916. He later took on studies of water and electrolyte homeostasis of aquatic animals and wrote two books Osmotic Regulation, published in 1939 and Comparative Physiology of Respiratory Mechanisms, published in 1941. During his career, Krogh contributed to more than 200 research articles in international journals.
Along with Johannes Lindhard, Krogh researched blood flow. They intended to find an explanation for the massive increase in the need for muscular work, because in order to do so, the blood flow of the venous blood in particular had to be highly variable and was not allowed to fill the cardiac ventricle completely during rest periods. Another result of Krogh’s experiments was a precise analysis of the increase in blood and oxygen flow in the muscles during exercise. Krogh’s research led to a better understanding of the involvement of blood capillaries in the musculature. The scientst was able to show that the capillary network of the musculature only fills up with blood when the muscle is active. He managed to investigate the process and discussed the activation of capillary blood flow and regulation. August Krogh received his Nobel Prize in Physiology or Medicine in 1920. After this big success, he continued his research in the field and published his results for instance in the influential book The Anatomy and Physiology of the Capillaries in 1922. Later on, Krogh expanded his research area and investigated heat regulation, the influence of nutrition and the capacity of muscle performance, the formation of lactic acid in muscles, training and muscle fatigue as well as the connection with kidney activity.
References and Further Reading:
- August Krogh at the Nobel Prize Foundation Webpage
- August Krogh at Britannica Online
- August Krogh Short Biography and Career