The concept of Homeostasis was first introduced by Cannon to describe the relative constancy of the internal processes of the body, such as blood oxygen and carbon dioxide levels, blood pressure, body temperature, blood glucose, and fluid and electrolyte balance. To Cannon, the word homeostasis did not imply something stagnant, set or immobile; it meant a condition that may vary but remained relatively constant. Cannon viewed the human being as a separate from the external environment and constantly endeavoring to maintain physiologic equilibrium, or balance, through adaptation to that environment.
Homeostasis, then, is the tendency of the body to maintain a state of balance or equilibrium while continually changing. The homeostatic mechanisms have four characteristics: they are self-regulating, they are compensatory, they tend to be regulated by negative feedback systems, they may require several feedback mechanisms to correct and they may require several feedback mechanisms to correct only one physiologic imbalance. In good health, a delicate balance of fluids, electrolytes, and acids and bases is maintained in the body.
This balance, or physiologic homeostasis, depends on multiple physiologic processes that regulate fluid intake and output and the movement of water and the substances dissolved in it between the body compartments. Almost every little illness has the potential to threaten this balance. Even in daily living, excessive temperatures or vigorous activities can disturb the balance if adequate water and salt intake is not maintained.
The volume and composition of body fluids is regulated through several homeostatic mechanisms. A number of body systems contribute to this regulation, including the kidneys, the endocrine system, the cardiovascular system, the lungs, and the gastrointestinal system. Reference: 1. Allender, J. A. , & Spradley, B. W. (2000). Community health nursing: Concepts and practice (5th Ed. ). Philadelphia: Lippincott Williams and Wilkins.