Essay from the year 2001 in the subject Biology - Human Biology, grade: 70/80, Oxford University (New College), language: English, abstract: Homeostasis is the ability of an organism to maintain a relatively constant internal environment despite changes in and exchanges with the external environment. The importance of a stable internal environment was emphasised by the French physiologist Claude Bernard as early as 1859. By maintaining a relatively stable internal environment, complex multicellular animals are able to live freely in changing external environments. The American physiologist Walter Cannon (1871-1945) called this stable state of the internal environment homeostasis, from the Greek words homeo (same) and stasis (staying). Homeostasis is dynamic and it is the result of compensating regulatory responses performed by homestatic control systems.