Respuesta :
The answer is excessive narrowing of blood vessels.
When exposed to the cold, our body tries to reduce its heat loss by tightening the arterioles under the skin (vasoconstriction). This mechanism increases the flow of blood into the deep veins and allows the body to maintain its internal temperature.
In people with Raynaud's disease, this reaction is excessive: the nerves that control the tightening of arterioles are hypersensitive and cause spasm, rather than normal vasoconstriction. When the spasm stops, the arterioles dilate again, restoring blood circulation.