Smooth muscles
in arterioles in the
skin.
Muscles contract causing
vasoconstriction. Less heat is
carried from the core to the surface
of the body, maintaining core
temperature. Extremities can turn
blue and feel cold and can even be
damaged (frostbite).
Muscles relax causing vasodilation.
More heat is carried from the core to
the surface, where it is lost by
convection and radiation
(conduction is generally low, except
when in water). Skin turns red.