Principles of Homeostasis


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12.1 Principles of Homeostasis

What is homeostasis?

Homeostasis is the maintenance of constant internal environment i organisms. It involves maintaining the chemical make up, volume and other features of the blood and tissue fluid within restricted limits.

Homeostasis is the ability to return to that set point and so maintain organisms in a balanced equilibrium.  

Maintaining a constant internal environment means that reactions can take place at a constant but predictable rate.

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The importance of homeostasis

Homeostasis is essential for the proper functioning of organisms for the following reasons:

- Enzymes that control the biochiemical reactionswithin cells and other proteins, such as channel proteins are sensitibe to changes in pH and temperature. Any change to these factors reduces the efficiency of enxymes or may even prevent them working altogether, temperature ofpH can impair the ability of enzymes to carry out their roles effectively. 

- Changes to water potential of the blood and tissue fluids may cause cells to shrink and expand, as a result of water leaving or entering by osmosis. In bothinstances the cellscannot operate normally. The maintenance of a constant blood glucose concentration is essential in ensuring a constant water potential. A constant blood glucose concentration also ensures a reliable source of glucose for respiration by cells. 

- Organisms with the ability to maintaina constant internal environment are more independant of the external environment. they have a wider geographical range and therefore have a greater chance of finding good and shelter etc. 

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Coordination of Control mechanisms

it is important to ensure that the information provided by receptors is analysed by thecontrol centre before action is taken. Receiving information from a number of sources allows a better degree of control. Information from the temperature centre in the brain may indicate that blood temperature is already above normal. This situation could arise during stenious exercise when blood temperature rises but sweating cools the skin. By analysing the informatino from all thedetectors, the brain can decide the best course of action - in this casenot to coordinate the action of the effectors  so that they operate harmoniously. For example, sweating wouldbe less effective in colling the body is it were not accompanied by vasodilation. 

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