7. When body temperatures exceed 98.6¾F,
several negative feedback loops are triggered which relax body hairs so they
lay flat, dilate blood vessels near the skin, increasing blood flow there so
heat may escape, and thus causing release of sweat from sweat glands via evaporation.
In some cases, cellular repsiration is decreased, thus releasing less heat.
All of these responses lower the body temp.
When the body temp decreases below 98.6¾F, the negative feedback
response releases hormones to stimulate cellular respiration, initiates minute
muscular contractions in the skin (shivering), and causes other skin muscles
to erect the hairs to trap heat. In addition, blood vessels to the skin may
constrict under more drastic body temp decreases. This keeps the warmer blood
in circulation in the core body areas and prevents the escape of heat.
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Slichter