Answer
The skin helps to control body temperature by two mechanisms:
1. By rerouting blood from the shell (periphery) to the core (internal parts) of the body
2. By sweating and heat loss by evaporation
Work Step by Step
Thermoreceptors are non-specialized nerve endings in the skin (and elsewhere) that sense changes in temperature.
a. If body temperature falls below normal body temperature range ( 97.7deg -99.5 deg F) because of a cold environment , the cutaneous blood vessels ( in the dermis) constrict ; this results in the rerouting of most of the blood to the deeper blood vessels of the core. This reduces heat loss and keeps the vital organs warm.
b. If body temperature rises above the normal set range( 36.5 deg C-37.5 deg. C) cutaneous blood vessels dilate, permitting an increase in blood flow to the periphery (shell). The skin can lose some heat by radiation and convection, but the most effective process by which the skin promotes cooling is sweating followed by evaporation. "The latent heat of vaporization is high" so this is a very effective heat-loss mechanism.
Normal body temperature varies slightly with age and where the temperature is taken-- mouth , axilla or rectum. The most common range given is 97 deg F -99 deg F (36.1 deg C-37.2 deg C). However, it has been proposed that 97.6 deg F- 99.6 deg F is a more accurate range from the preteen years to the middle sixties.
