What happens in the arteriovenous shunts present in the finger tips and toes when temperatures are cold?

What happens in the arteriovenous shunts present in the finger tips and toes when temperatures are cold?

• A. Colder temperatures will result in vasoconstriction
• B. Warmer temperatures will result in vasoconstriction
• C. They become permanently closed
• D. They move blood away from skin to core

Answer: (A)

Cold exposure triggers sympathetic signals that constrict cutaneous vessels, including the arteriovenous shunts in the fingertips and toes. This vasoconstriction reduces blood flow through the skin and the shunts, so less heat is lost to the environment and blood is kept toward the body’s core. These shunts aren’t permanently closed; they dynamically respond to temperature—warming tends to promote dilation to release heat.

Cold exposure triggers sympathetic signals that constrict cutaneous vessels, including the arteriovenous shunts in the fingertips and toes. This vasoconstriction reduces blood flow through the skin and the shunts, so less heat is lost to the environment and blood is kept toward the body’s core. These shunts aren’t permanently closed; they dynamically respond to temperature—warming tends to promote dilation to release heat.