Arrector pilorum

The skin s mechanism of heat conservation involves its very complex circulatory system [2,3]. To conserve heat, blood is diverted away from the skin s periphery by way of the arteriovenous anastomoses. The ex-ternalmost circulation of the blood is effectively shut down, leading to a characteristic blanching of the skin in fair-skinned individuals. Less heat is irradiated and convectively passed into the atmosphere. Furry mammals have yet another mechanism to conserve body heat. Each tiny arrector pilorum stands its hair up straight, adding appreciable thickness to the insulating air layer entrapped in the fur, reducing heat loss. 

Only the sympathetic system supplies the ureters, uterus, uterine tubes, vasa deferentia, blood vessels (which are constricted), sweat glands (actually cholinergic, however, fig. 3) and ihe arrectores pilorum which are contracted. 

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