August Krogh discovered the capillaries and determined how they are working. Because of that important discovery, he was Medicine Nobel prize winner in 1920. Capillaries are a very important element of blood net. In short, they are linking the arterioles and venules, having an autonomous working way, peristaltic one. Capillaries net is the biggest exchanger of the body, with about 7176 sq yd (6000 m²), estimation from A. Krogh himself. However, they are very small vessels of about few microns’ diameter, which can triple their diameter on the demand.
Their function is to feed with food, oxygen, information, and remove waste toward and from the cells in a perimeter of about 15 microns (A. Krogh), by osmotic exchanges through their wall. It’s to say that during the connection to an arteriole, pressure inside capillary increase, allowing the diffusion toward the cells. And in the second time, during their connection to the venules, pressure decrease, allowing transfer back to the blood (CO2, wastes).
All hereunder information are from Wikipedia
August Krogh was born on 1874, November, 15th in Grenaa, in Denmark. He was physiologist, professor of zoophysiology at Copenhagen University from 1916 to 1945.
He discovered lot fundamentals in physiology, defining the “Krogh constant” as example.
In 1920 August Krogh was awarded the Nobel Prize of Medicine for the discovery of the capillaries and their regulation’s mechanism in skeletal muscle. A. Krogh was first to describe the adaptation of blood perfusion in muscle and other organs according to demands through opening and closing the capillaries, connecting arterioles to venules.
He was one of the pioneers of comparative studies on animals. He got his physiology’s doctorate in 1915, with a study of the respiration through the skin and the lungs of frogs, named “Animal breathing exchanges”.
Later on, he worked on the osmotic functions of water and salts in the aquatic animals and published Osmotic regulations in 1939 and Comparison of physiological breathing mechanism in 1941. He wrote as well over 200 scientific articles. He built several scientific tools, of which 2 of them are still in use today: spirometer and metabolism measurement one.
After the discovery of insulin in 1922 (Banting & Best, Canada), he with Dr Hagedorn started insulin production in Denmark.
Main part of his work was produced with the collaboration of his wife, Marie Krogh (1874-1943), who was renown scientist as well.
He died in 1949, September 13th.