Rudolf Heidenhain

Rudolf Peter Heinrich Heidenhain (January 29, 1834 - October 13, 1897) was a German physiologist who was born in Marienwerder, East Prussia (now Kwidzyn, Poland). He studied medicine at the Universities of Halle and Berlin. After receiving his doctorate, he remained in Berlin as an assistant to Emil du Bois-Reymond (1818-1896). In 1856 he returned to Halle and worked in the laboratory of Alfred Wilhelm Volkmann (1801-1877). In 1859 he attained the chair of physiology at the the University of Breslau, where he remained for the rest of his career. Two of his famous students at Breslau were Karl Weigert (1845-1904) and Ivan Petrovich Pavlov (1849-1936).

Heidenhain is remembered for his work involving muscle and nerve physiology, particularly in the study of physiological thermoelectrics. He demonstrated the muscles' self-regulatory process for expenditure of energy, as well as its ability to "economize" energy. Heidenhain showed that total output energy (heat and mechanical work) increases with an increased load, in other words, a muscle freed more energy when resistance to its contraction was greater. Also, when a muscle was fatigued, it had the ability to work more economically. Heidenhain's research also dealt with the study of heat production during muscular activity. He was able to detect and measure a small increase of temperature during the slightest muscular movement.

Heidenhain did extensive research concerning the secretory and absorption processes of glands. He studied the stomach's gastric glands and the processes it used to produce pepsin and hydrochloric acid. Also, the eponymous demilunes of Heidenhain were described by him. These are half-moon shaped cellular structures associated with the salivary glands.

Heidenhain also performed scientific studies on hypnotism. His research was from a physiological basis, and he explained hypnosis in terms of inhibition of the cortex. Later, Ivan Pavlov carried on Heidenhain's physiological studies of hypnosis. Also, while an assistant in Halle, Heidenhain made improvements on Hermann Welcker’s (1822-1897) methodology for measurement of blood volume. His son, Martin Heidenhain (1864-1949) was a highly regarded anatomist.