Question

Consider the mechanisms used to maintain homeostasis and especially the components of the feedback loops used to maintain variables around their set points. Why is it beneficial to have redundant or antagonistic control over a given variable?

Answer 1

Homeostasis is the maintenance of steady state of physical ,interna and chemical conditions in a living system.It maintains the functioning of the body within certain limits or homeostasis range.Parmeters like body temperature,blood pH ,glucose level and all the normal functioning of the body is kept constant by the mechanism of holeostatis.For example,to maintain the body temperature some mammals show behavioral response like basking in sun.Deposition of fat under skin,concentration of urine are some adaptations to reduce water lose from body.Size of limbs ,nose,ears etc are also adaptations in mammals to maintain the body temperature.Homeostasis os maintained by Negative feedback and rarely by positive feedback.Negative feedback involves mechanisms to bring down the changes to their set points or homeostasis range.If the functioning of body deviates from the normal conditions,negative feedback counteract the changes and bring back the deviation to the preset values.For example,when we exercise hard,our body temperature rise above the set values.So body will activate mechanisms like sweating,increased blood flow to the skin etc. to cool down the temperature to the set value.The components of negative feedback are a sensor or receptor, the control center and the effector .The sensor or receptor detects the change or deviation in the physiological system and conveys this to the control center.Control center compares the deviation to its normal range.If the deviation is strong it triggers the effector.Effector apply mechanisms to reverse the change to its normal set values.For example when the body temperature rises due to severe exercise,the rise in the body temperature is the stimulus which is detected by the nerve cells in the skin and brain which acts as the effector.They send signals to the temperature regulatory center in brain (control center).The signals are sent from brain to the sweat glands which act as the effector and induce sweating to cool down the temperature.

Positive feedback helps the body to continue in the state of change or deviation.This feedback occurs during childbirth and body's response to blood lose.It doesn't reverse the change but insist to continue in that change until a definite end point is reached.

Antagonistic control over a given variable helps to reverse the change and bring back to the set values or normal range.A change from the normal functioning leads to upnormal physiological functioning.So this control mechanism acts against this change ,reverse the change and brings to normal range.While in positive feedback,it allows the body to continue with the change without maintaining the homestasis.So it is beneficial to have antagonistic control over a given a variable.