Homeostasis is the tendency of the body to maintain a stable internal environment for cells by narrowly regulating critical variables.
- Oxygen tension
Any disruption to optimal homeostatic conditions will elicit multiple regulatory responses by the body In an attempt to bring disrupted variables back to normal levels.
For example, when you ascend the high altitude, due to the low oxygen pressure in the inspired air, oxygen levels in your blood drop below desired levels. As a result, you're nervous, endocrine, cardiovascular and respiratory systems, makes adjustments in an attempt to compensate for this disruption in homeostasis.