It is the tendency of an organism or cell to regulate its internal environment and maintain equilibrium, usually by a system of feedback controls, so as to stabilize health and functioning.
Homeostasis or homoeostasis (homeo- + -stasis) is the property of a system in which variables are regulated so that internal conditions remain stable and relatively constant. Examples of homeostasis include the regulation of temperature and the balance between acidity and alkalinity (pH). It is a process that maintains the stability of the human body's internal environment in response to changes in external conditions. Positive and Negative Feedback loops. The negative feedback loop brings the body closer to the set point at which the internal environment of the human body operated. For example, during the cold weather the body uses the thermoregulatory centre to try and keep the body temperature at a constant. The feedback loops are used to inform the body about changes that occur internally and externally. Humans need homeostasis to keep the desired set point at a constant, and with the help of the feedback loops, the body is able to keep the internal environment of the body at the set point. Control systems that keep such conditions constant are examples of homeostasis; this is the maintenance of constant internal conditions in an organism. Negative feedback is an important type of control that is found in homeostasis. A negative feedback control system responds when conditions change from the ideal or set point and returns conditions to this set point. There is a continuous cycle of events in negative feedback.  Positive feedback mechanisms. A positive feedback mechanism is the exact opposite of a negative feedback mechanism. With negative feedback, the output reduces the original effect of the stimulus. In a positive feedback system, the output enhances the original stimulus. A good example of a positive feedback system is child birth. Almost all homeostatic control mechanisms are negative feedback mechanisms. These mechanisms change the variable back to its original state or “ideal value”. A good example of a negative feedback mechanism is a home thermostat (heating system). Negative Feedback and Stability. The usual means of maintaining homeostasis is a general mechanism called a negative feedback loop. The body senses an internal change and activates mechanisms that reverse, or negate, that change. An example of negative feedback is body temperature regulation. Often, however, positive feedback produces the very opposite of homeostasis: rapid loss of internal stability with potentially fatal consequences. For example, if the death of a small area of heart tissue triggers a heart attack (myocardial infarction), the heart pumps an inadequate amount of blood. There are several negative feedback in biological system to regulate and maintain homeostasis. Some of which are the regulation of hormone synthesis, blood glucose levels, body temperature, and baroflex in blood pressure. Compare: positive feedback. See also: feedback mechanism. Negative feedback. Definition. noun. A feedback in which the system responds in an opposite direction to the perturbation. Supplement. It is a self-regulatory system in which it feeds back to the input a part of a system’s output so as to reverse the direction of change of the output. : Some definitions state or imply that homeostasis. the stable condition in which the body is maintained by the action of feedback systems making appropriate adjustments as necessary. Other definitions* of homeostasis state that homeostasis is the (active) maintenance of stable conditions within the body. 1 Negative Feedback Systems (Negative feedback mechanisms). 2  Produce negative feedback which means that negative feedback systems reverse changes in the controlled condition, hence negative feedback tends to bring conditions within the body back into balance. 3  Positive Feedback Systems (Posi Homeostasis. The biological definition of homeostasis is “the tendency of an organism or cell to regulate its internal environment and maintain equilibrium, usually by a system of feedback controls, so as to stabilize health and functioning”. Almost all homeostatic control mechanisms are negative feedback mechanisms. These mechanisms change the variable back to its original state or “ideal value”. A good example of a negative feedback mechanism is a home thermostat (heating system).
https://en.wikipedia.org/wiki/Homeostasis http://homeostasisinhumans.weebly.com/feedback-loops.html http://www.bbc.co.uk/bitesize/higher/biology/control_regulation/homeostatic_control/revision/1/ http://anatomyandphysiologyi.com/homeostasis-positivenegative-feedback-mechanisms/ http://www.biologyreference.com/Ho-La/Homeostasis.html http://www.biology-online.org/dictionary/Negative_feedback http://www.ivyroses.com/HumanBody/Homeostasis.php http://anatomyandphysiologyi.com/homeostasis-positivenegative-feedback-mechanisms/
positive feedback homeostasis definition