With Reference to Specific Examples and Mechanisms Assess the Significance of Homeostasis to the Human Body.

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With Reference to Specific Examples and Mechanisms Assess the Significance of Homeostasis to the Human Body

Homeostasis derives from the Greek word homeo meaning same and stasis meaning staying, therefore homeostasis refers to the maintenance of the stability of the internal environment within a body, giving an organism a level of internal independence from the external environment (1).

The actual environment of the cells of the body is the interstitial component of the Extra-Cellular Fluid (ECF), this fluid has to be kept constant from the changing external environment or necrosis occurs. Since normal cell function depend upon the constancy of this fluid, it is not surprising that in multicellular animals, an immense number of regulator mechanisms have evolved to maintain it. W.B cannon used the term homeostasis to describe the various physiological arrangements which serve to restore the normal state once it has been disturbed (2).

Homeostatic mechanisms involves the interactions of many organs and systems in providing the optimum conditions for the cells, which results in optimum environment for the enzymes to work in thus keeping the cell alive. The mammalian kidney is central to homeostasis, being involved in the regulation of water and salt balance, pH and metabolites levels. The liver is centrally concerned in the regulations of the metabolite levels and thermogenesis. The hypothalamus monitors pH, osmotic pressure and temperature and it brings about the regulation either by direct affect on the nervous system or via the hormones from the pituitary gland. (1)

The buffering properties of the body fluids and the renal respiratory adjustments to the presences of excess acid and fluid are more examples of homeostatic mechanisms. The other factors in the internal environment which must be maintained within narrow limit include temperature, glucose levels, O2 and CO2 levels. (3)

The homeostatic processes which intend to maintain a possible alternating feature within narrow limits all use a mechanism known as negative feedback. In these mechanic systems there are three basic elements; detector/receptor which send information to the control centre/integrator. This control centre determines the limits within which the changeable feature is kept. This receives information from one or more receptors and sends out signals appropriate to this information to the effector (4). The effector responds to the incoming signals sent by the control centre and affirms that modifications are needed.

There are generally two ways the body can respond to a change. In the negative feedback mechanism the effector response negates the effect of the original stimulus thus restoring homeostasis. This level is called the 'norm' because it is which the body finds most suitable. There is also the possibility of positive feedback mechanism. In these mechanisms, the result or response enhances the original stimulus so that the activity (output) is accelerated. This feedback mechanism is "positive" because the change that occurs proceeds in the same direction as the initial disturbance, causing the variable to deviate further and further from the original value or range (5). This does not return to the norm and has a destabilising effect and therefore not result in homeostasis. There are two behavioural mechanisms that are involved in homeostasis; they are intrinsic and extrinsic regulation.
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Intrinsic involves internal motivation which benefit the body such as organs and muscles contraction and extrinsic is stimulated by external conditions which benefit the person such as putting on a jacket.

Homeostasis is so important that most diseases is regarded as a results of its disturbance, a condition called homeostatic imbalance (6). Homeostatic imbalance is therefore the disruption of homeostatic mechanism where there is little change in homeostatic mechanisms in young and old during rest but it has been demonstrated that the rate of readjustment to normal equilibrium after stress is slower in old compared to ...

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