Sep. 24th, 2012
Homeostasis (Body Temperature)
There is an initial change in your internal body temperature. The normal body temperature is called the set point and your body temperature drops below the set point. The immediate increases of heat loss from your warm skin upsets the dynamic balance between heat gain and heat loss. Your internal body temperature falls. The first homeostatic responses is that abode vessels to the skin narrow, reducing the amount of warm blood flowing through the skin and therefore reducing heat loss. Given that there is no way to stay worm, e.g., putting on a jacket, it is necessary for the body to produce more heat to stay warm. Involuntary, shivering, or voluntary, exercise, muscle activity may be used to generate heat. The chemical reactions of muscle active generates heat which raises the body temperature. The internal body temperature rises towards the set point. As long as the internal temperature remains below the set point, there will be a tendency to remain active and generate more heat. If excess exercise is done, the temperature will rise above the set point and sweating may occur. As the temperature increases above the set point the desire for exercise will decrease.
All homeostatic mechanisms use negative feedback to maintain a constant value. Negative feedback means that whenever a change occurs in a system, this automatically causes a corrective mechanism to start, which reverses the original change and brings the system back towards the set point. It also means that the bigger the change the bigger the corrective mechanism. Negative feedback applies to electronic circuits and central heating systems as well as to biological systems. When your oven gets too hot, the heating switches off; this allows the oven to cool down. Eventually it will get too cold, when the heating will switch back in, so raising the temperature once again. So, in a system controlled by negative feedback,...
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