August Krogh - Danish Men, Family and Childhood

Schack August Steenberg Krogh was born on November 15, 1874, at Grenaa, Jutland, Denmark to Viggo Krogh and Marie, née Drechmann. His father was a shipbuilder.

A child prodigy, young Krogh’s interest in natural science developed early. When boys of his age played sports, Krogh immersed himself in experiments. He widely read books in botany, zoology, physics and chemistry.

As a young man, Krogh attended a lecture on medical physiology by Professor Christian Bohr. Impressed by the latter and inspired by his teacher friend William Sorenson, Krogh decided to make a career in physiology.

In 1893, Krogh enrolled at the University of Copenhagen as a student of medicine. However, he couldn’t keep himself away from studying zoology. In 1897, he started working under Professor Bohr at the Laboratory of Medical Physiology. In 1899, upon completing his examination in zoology, he received the appointment of an assistant to Professor Bohr.

In 1903, Krogh earned his doctorate degree. His thesis was on the respiratory exchanges of oxygen and carbon-dioxide in the lung and skin of frogs.

Following his doctorate degree, Krogh became highly interested in the gas exchange of the living organism. He submitted a paper on the pulmonary exchange of nitrogen wherein he demonstrated that free nitrogen played no role in respiratory exchanges. He backed up his work with careful experiments that used chrysalides, eggs and mice in a temperature-controlled apparatus. The work won him Seegan Prize of the Austrian Academy of Sciences.

Krogh adopted his own method of study and extended his research on respiration to other animals as well. During this time, Krogh believed that pulmonary exchanges took place through secretory processes regulated by nervous system. He also devised an instrument called tonometer and a device for microanalysis of gases.

In 1904, he published, with Bohr and K. A. Hasselbalch, a study on the relation between the carbon dioxide tension and the oxygen association of blood. His initial belief that lung secreted oxygen into the bloodstream was later given away for the new fundamental that pulmonary gas exchange was only dependent on diffusion.

Following the establishment of the fact that absorption of oxygen and elimination of carbon dioxide from the lungs is carried out by diffusion, a number of articles came up that criticized this new point of view and highlighted the problems. Krogh spent the following years publishing works concerning blood flow through lungs.

In 1908, a special associate professorship of zoo-physiology was created at the University of Copenhagen exclusively for Krogh. Leaving Bohr’s laboratory, Krogh set forth to make new discoveries and research in the field. In 1916, it was changed to an ordinary chair.

Having no laboratory of his own, Krogh refurnished his residence to turn it into a laboratory. Therein, he developed many instruments that evaluated the function of blood flow and respiration such as the rocker spirometer, the electromagnetic bicycle ergometer, and a gas analysis apparatus accurate to 0.001 per cent.

From 1915, Krogh turned his attention to the mechanism in which blood capillaries supplied oxygen to muscle cells and removed carbon dioxide from them through exercise. This study concluded the fact that blood capillaries remained open while working and closed at the time of rest.

With the help of intensive microscopical and histological methods, Krogh finally proved his hypothesis of the opening and closing of blood capillaries. He determined that the capillaries were metabolically controlled. This became the masterpiece of his career and drew him stunning success. His work helped him bag the coveted Nobel Prize in Physiology or Medicine in 1920.

In 1922, Krogh came up with his book, ‘The Anatomy and Physiology of the Capillaries’. Through it, he emphasized the fact that capillary movement were influenced by both nerves and hormones, a research carried out in association with numerous foreign scientists. Interestingly, till date the book exudes dominant influence for its implication on cell metabolism, water balance, inflammation and disease.

In 1922, Krogh undertook a lecture trip to America. Therein, he first found about the then newly-discovered insulin. Upon returning to Denmark, he along with internist H.C. Hagedorn, organized the fabrication of insulin. The duo established two institutions, Nordisk Insulinlaboratorium and Nordisk Insulinfond. He even worked on the standardization of insulin with A. M Hemmingsen.

In 1928, the Rockfeller Institute was officially established at the Rockfeller Complex. The complex had other institutes as well, the institute of medical physiology and biophysics, and the institute for the theory of gymnastics.

At the Rockfelller Institute, Krogh carried out his research on heavy muscle work. He created new methods for determination of total osmotic tension of blood and studied the balance of insensible perspiration. During this time, he also showed his interest on the physiological problems of heating house

In 1934, he withdrew from his academic duties and in 1945, officially retired from the university. However, this did not mean the end of his career. He continued with his research and studies privately at his home laboratory. Post retirement, he took to studying the flight of insects and grasshoppers. He even studied the development of bud in trees.

In his lifetime, Krogh contributed more than 200 research articles in international journals. He studied water and electrolyte homeostasis of aquatic animals and published two books in the genre as well, ‘Osmotic Regulation’ and ‘Comparative Physiology of Respiratory Mechanisms’

Though Krogh achieved new academic heights in the field of physiology, he never really gave up on his love for marine biology, insect physiology and osmotic relationship in plants and animals. He continuously returned to read vigorously about each of the fields and kept himself updated with the new research works.

Krogh most remarkable work as a scientist and professor of zoophysiology came with his discovery of the mechanism of regulation of the capillaries in the skeletal muscle. The work helped in the better understanding of the anatomy and physiology of the capillary system. It also earned him a Nobel Prize in Physiology or Medicine in 1920.

Krogh was the man behind the ‘Krogh Principle’ which stated 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’. The concept is till date dominant to those disciplines of biology relying on comparative method, such as neuroethology, comparative physiology, and functional genomics.

Krogh was bestowed with the prestigious Nobel Prize for Physiology or Medicine in 1920 for his discovery of the mechanism of regulation of gas in blood capillaries in muscles.

He received honorary doctorate degrees from various universities across the globe including Edinburgh, Budapest, Lund, Harvard, Göttingen, Oslo, and Oxford.

He was made a member of the Academy of Sciences, Denmark. Furthermore, he was appointed as a foreign member of numerous academies and societies, including The Royal Society, London.

In 1939, he was declared honorary citizen of Grenaa.

He was awarded the Baly medal of the Royal College of Physicians, London in 1945.

Krogh married Birte Marie Jörgensen, a medical student and later a scientist, in 1905. The couple was blessed with four children, a son and three daughters. Their son became a Prosector of Anatomy at the University of Arahus. Marie died in 1943

August Krogh died on September 13, 1949, at the age of 74, in Copenhagen.