Homeostatic

Homeostasis is the state of steady internal, physical, and chemical conditions maintained by living systems. This dynamic state of equilibrium is the condition of optimal functioning for the organism and includes many variables, such as body temperature and fluid balance, being kept within certain pre-set limits (homeostatic range). Other variables include the pH of extracellular fluid, the concentrations of sodium, potassium and calcium ions, as well as that of the blood sugar level, and these need to be regulated despite changes in the environment, diet, or level of activity. Each of these variables is controlled by a separate "homeostat" (which operates by feedback mechanisms that take place at the level of the cell and the organism). Collectively, these maintain life.

Mechanisms

The mechanisms of homeostasis are based on the principle of feedback regulation. In feedback regulation, the output or product of a process is used as an input to control the behavior of the process itself, often regulating the production of more product. Feedback regulation can be either positive (the output enhances the original stimulus) or negative (the output reduces the original stimulus).

Role in disease

Disease is a result of a failure in homeostasis. Many diseases are a result of homeostatic failure, such as heart failure where the homeostatic control of arterial blood pressure is not able to compensate for changes in blood volume or peripheral resistance. Other diseases which result from a homeostatic imbalance include diabetes, dehydration, hypoglycemia, gout, and any disease caused by the presence of a toxin in the bloodstream.

See also

• Physiology
• Human body
• Health
• Disease

References

Homeostatic Resources
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