The ability of an organism to change internally or externally in relation to changes in the environment is called Homeostasis. Example of some of the most common things which organisms can regulate in response to the changes in environment are body temperature, blood pressure, volume of body water, blood sugar/glucose level etc. These changes help the organism to maintain a constant equilibrium with the external environment in order to support their vital functions. There are various organs in the body which are responsible for Homeostasis but commonly in mammals the signals for such changes are sent by brain. However in less complex life forms, these changes can also be done local to the organ.
