The body’s ability to maintain homeostasis is a critical function. In biology, homeostasis is the state of steady internal physical and chemical conditions maintained by living organisms. The body has many aspects that it maintains using homeostatic control mechanisms including: optimal temperature, fluid balance, cerebrospinal fluid, pH of extracellular fluid, concentrations of oxygen, carbon dioxide, sodium, potassium, calcium ions, copper, iron levels, blood sugar levels, plasma pH, blood oxygen content as well as blood pressure. These levels are kept within certain pre-set limits (homeostatic range) even during changes in the environment, diet, or level of activity.