Throughout everyday life rarely do we give thought as to how our trillions of cells- throughout constant contact- are maintained to produce a relatively stable environment. This marvellous process is termed homeostasis (ho” me-o-sta’sis), named by twentieth century physiologist Walter Cannon.
The literal term of homeostasis is ‘unchanging’, however this does not accurately describe the process at first thought. The body is striving to maintain a level state of equilibrium (or balance), therefore is constantly adjusting, creating – in actual effect- a dynamic state. The body is striving to maintain unchanged conditions by constantly adapting. Homeostasis regulation is controlled through the nervous (electrical) and endocrine (chemical) systems.
The homeostasis process runs through a path which involves three main components: the receptor, the control centre and finally the effector. The receptor will pick up data or signals called stimuli, and will then send it through the afferent pathway to the control centre. The control centre is your brain, which will decide what action to take, once our control centre makes its decision it will send the signals along the efferent pathway to the effectors to process the decision.
An example of the above point would be in the situation when an individual’s body temperature rises where the receptors will send a signal to our inbuilt thermostat in the brain (hypothalamus), which acts as our control centre. The control centre will then send a signal through the efferent pathway to 1) allow the skin blood vessels to dilate, enabling the capillaries to fill with warm blood 2) activate sweat glands- therefore raising evaporative cooling. At the bottom line, without the process of homeostasis the body will not be able to efficiently function.
Two categories in which homeostasis can be split into is negative feedback and positive feedback.
Negative feedback is the most common homeostatic mechanisms. In this process the control centre will send signals to shut off, or reduce the intensity of the original stimulus, for example when your heart rate increases through exercise negative feedback is delivered to maintain a relatively moderate heart rate rather than going beyond its 100% maximum. Negative feedback will always move in the opposite direction of the original stimulus. Think of negative feedback mechanisms as correctional officers at a prison, whenever the inmates try and escape the offers bring the inmates back to where they should be.
Positive feedback is not as common as negative. It will always be heading in the same direction as the original stimulus, and will quite often result in an escalating water fall effect in that the initial positive feedback will result in more of the same- but in greater numbers, this is termed the cascade effect. An everyday functional example of positive feedback is in the case of an individual wanting pass urine- but not having the opportunity to do so. As time passes the urge increases; hence the process of positive feedback.
Whilst homeostasis is an amazing system, there is a flip side: homeostatic imbalance. Homeostatic imbalance is quite often the cause of most disease and illness. As we get older our ability to use homeostasis decreases as our bodies control systems lose their ability to function- which will lead to health problems. An example of homeostatic imbalance is when a prize fighter ages and loses his ability to absorb punishment.
When negative feedback mechanisms are overwhelmed they can be replaced by positive feedback mechanisms, therefore producing the opposite to homeostasis- and disastrous results.
The most important fact to acknowledge is that negative feedback mechanisms are more predominantly used over positive due to the function of the body. Many of the body’s organs rely on regulation to maintain a steady level for functioning in everyday life. As previously discussed, it is the negative feedback mechanism which facilitates this process, whereas the positive feedback mechanisms are only used on the occasions that the body is not regularly accustomed to adjusting to.
Negative feedback could be related to a football team coach who’s day to day job is to make sure things are running smoothly- allowing the opportunity for improvement, whereas positive feedback is more likened to a clubs board of directors; who primarily only take action in times of uncertainty and panic.
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