How Your Body Maintains a Constant Temperature: Thermoregulation

By Maggie Norris, Donna Rae Siegfried

All metabolic reactions in all organisms require that the temperature of the body be within a certain range. Because humans are homeotherms or “warm-blooded,” you maintain a relatively constant body temperature regardless of the ambient temperature. You do this by regulating your metabolic rate. The large number of mitochondria per cell enables a high rate of metabolism, which generates a lot of heat.

Regulating body temperature requires a steady supply of fuel (glucose) to the mitochondrial furnaces.

Another way you control your body temperature is by employing adaptations that conserve the heat generated by metabolism within the body in cold conditions or dissipate that heat out of the body in overly warm conditions. A few of the specific adaptations include the following:

  • Sweating: Sweat glands in the skin open their pores to dissipate heat by evaporative cooling of water from the skin. They close to conserve heat. Sweat glands are opened and closed by the action of muscles at the base of the gland, deep under the skin.
  • Blood circulation: Blood vessels close to the skin dilate (enlarge) to dissipate heat in the blood through the skin. They constrict (narrow) to conserve heat. That’s why your skin flushes (reddens) when you’re hot: That’s the color of your blood visible at the surface of your skin.
  • Muscle contraction: When closing sweat pores and blood vessel constriction are not enough to conserve heat in cold conditions, your muscles will begin to contract automatically to generate more heat. This reaction is familiar as “shivering.”
  • Insulation: Regions of fatty tissue under the skin provide insulation, holding the warmth of the body in. Body hair aids in this, too (though not enough to keep us from needing a nice, warm winter coat).