What are the key ideas surrounding homeostasis?

Homeostasis is the maintenance of internal environments within a set narrow range (based around a set point) which is critical for survival. The environment remains relatively stable so reactions can occur at the optimum rate. For homeostasis, a variable, sensor and an effector is needed. Negative feedback is where the variable (which has deviated out of the set range) is set back to the set point – the bigger the change the bigger the effect. Positive feedback has a destabilisation effect by amplifying signals (not part of homeostatic mechanisms but associated with homeostasis in the way that positive feedback also uses a variable, sensor and an effector). Closed loop systems are used, through which the effector brings the variable back within normal ranges. Stability of all body functions is maintained by closed loops with negative feedback to cancel deviations form optimum level. However, extreme conditions can disable negative feedback mechanisms.