controlling body temperature requires...
- temperature receptors in the skin to detect the external temperature
- temperature receptors in the brain to measure the temperature of the blood
- then brain which acts as a processing centre, to receive information from the temperature receptors, responding by triggering the effectors
- effectors (sweat glands and muscles) to carry of the automatic response
if your body temperature is too high, heat needs to be transferred to the environment. this is done by sweating, since evaporation from the skin requires heat energy from the body.
if your body temperature is too low, your body will start to shiver. shivering is the rapid contraction and release of muscles. these contractions require energy from increased respiration, and heat is released as a by-product, warming surrounding tissue.
vasondilation and vasoconstriction
blood temperature is monitored by a centre in your brain called the hypothalamus.
in hot conditions, blood vessels in the skin dilate, allowing more bloody to flow through the skin capilleries. this means that more heat is lost from the surface of the skin by radiation. this is called vasodilation.
in cold conditions, blood vessels in the skin constrict, reducing the amount of blood that flows through the skin capilleries. this means that less heat is lost from the surface of the skin by radiation. this is called vasoconstriction.