This is a careful, well documented study of the function of the arteriovenous anastomoses in the fingers and toes of man. These shunts are under the dual control of the central nervous system and the local thermal influence. While the arteriovenous anastomoses control the skin temperature through volume changes in the superficial venous bed, the arterioles and capillaries operate by generalized dilatation which results both in increased temperature and in redness of the skin.
Regulation of temperature is governed by two separate and distinct centers. At moderate room temperatures small variations are stabilized by the help of the shunts, which affect the caliber and regulate the heat dissipation from superficial veins. At high temperatures heat radiation is initiated by a dilatation of the skin arterioles, capillaries and small veins together with the secretion of sweat. The shunts do not seem to be dependent on the cerebral cortex for their thermoregulatory