Homeostasis can be defined as the maintenance of a *stable internal environment through negative feedback despite fluctuations in the external environment.
((*stable = conditions fluctuate within a narrow range about a set point))
- Ion concentration in the blood
- Glucose concentration in the blood
The Role Of Homeostasis
- Homeostasis provides a constant internal environment and independence from fluctuating external conditions.
- Features that influence internal environment have a set level ((called the 'norm')).
- Any changes from the norm are called 'deviation'.
- Negative feedback is caused by deviation from the norm; it results in a return to the norm.
- When the body experiences changes in the external environment, the homeostatic system evens out the variations experienced by the body in a number of ways:
- The liver can store or release glucose
- Blood is kept at a constant, ideal state; glucose concentration remains at 80mg/cm3
- Tissue fluid surrounding the cells has constant ideal conditions and contains the optimum glucose concentration for respiration to occur