Homeostasis
Quick Definition
The body's ability to maintain stable internal conditions (like temperature and pH) despite changes in the external environment.
In-Depth Explanation
Homeostasis is a fundamental concept in physiology referring to the body's dynamic process of maintaining relatively stable internal conditions. The term was coined by Walter Cannon in 1926 and derives from the Greek words for 'same' and 'steady.'
Key homeostatic systems regulate body temperature (thermoregulation), blood glucose levels, blood pressure, pH balance, fluid balance, and calcium levels. These systems use feedback loops -- primarily negative feedback -- where a change triggers responses that reverse the change and restore equilibrium.
When homeostatic mechanisms fail, disease results. For example, diabetes occurs when blood sugar regulation fails, and hypertension reflects impaired blood pressure control. Many health practices -- from sleep hygiene to nutrition to exercise -- ultimately support the body's homeostatic processes.