Which physiological change accompanies cutaneous vasodilation during heat stress to promote heat loss?

• A. Decreased ventilation
• B. Increased heart rate and cardiac output
• C. Decreased sweating
• D. Decreased skin temperature

Answer: (B)

Cutaneous vasodilation during heat exposure moves more warm blood to the skin, increasing heat transfer from the core to the body surface for loss via radiation, convection, and sweating. As vessels in the skin dilate, systemic vascular resistance drops, which can lower arterial pressure. To keep blood pressure and perfusion adequate, the heart rate rises and cardiac output increases. The higher cardiac output helps push more blood through the dilated skin, supporting heat loss while maintaining circulation to vital organs. Ventilation typically increases rather than decreases, sweating increases rather than decreases, and skin temperature rises rather than falls, so these options don’t fit.