As ambient temperature approaches normal skin temperature, which is true about the body's ability to dissipate heat?

• A. Cooling becomes easier
• B. Blood brought to the body can lose heat
• C. Evaporation becomes the primary means of temperature regulation
• D. Sweat glands stop functioning

Answer: (C)

When ambient temperature gets close to skin temperature, the gradient for dry heat loss (radiation, convection, and conduction) shrinks, making those dry methods less effective. The body then relies on evaporative cooling to shed heat, because evaporation can remove heat without needing the surrounding air to be cooler than the skin. Sweat evaporates from the skin, and the latent heat required to vaporize that water carries heat away from the body, helping to lower core temperature even when the air is warm. Humidity can hinder evaporation, but it remains the dominant cooling mechanism in this scenario. So, evaporation becomes the primary means of temperature regulation as the environment approaches normal skin temperature.