Blushing causes the face and neck to redden and become warm. It occurs when the capillaries, the tiny blood vessels in the skin, suddenly swell with blood. Vasodilator nerves in the capillaries cause blood vessels to expand and fill with blood. Blushing results from stimulation of these nerves, which may be stimulated by anxiousness, cold temperatures, increased physical activity, or nervousness. Vasoconstrictor nerves cause the blood vessels to contract, and produce pale skin when stimulated by warmth, nervousness, or illness. See also Capillary .
