In response to cold exposure, how do the arteriovenous shunts in the digits typically respond?

In response to cold exposure, how do the arteriovenous shunts in the digits typically respond?

• A. Vasoconstriction
• B. Vasodilation
• C. No change
• D. Hemorrhage

Answer: (A)

Cold exposure triggers a sympathetic vasoconstrictive response in the skin to conserve heat. In the digits, the arteriovenous shunts constrict as part of this response, which reduces cutaneous blood flow to limit heat loss from the extremities. By narrowing these shunts, less blood bypasses the capillary beds and overall warmth is retained in the core. If these vessels were to vasodilate, more heat would be lost through the skin. A lack of change wouldn’t account for the noticeable drop in blood flow, and hemorrhage isn’t a normal mechanism of thermoregulation.

Cold exposure triggers a sympathetic vasoconstrictive response in the skin to conserve heat. In the digits, the arteriovenous shunts constrict as part of this response, which reduces cutaneous blood flow to limit heat loss from the extremities. By narrowing these shunts, less blood bypasses the capillary beds and overall warmth is retained in the core. If these vessels were to vasodilate, more heat would be lost through the skin. A lack of change wouldn’t account for the noticeable drop in blood flow, and hemorrhage isn’t a normal mechanism of thermoregulation.