Human body Temp Control -Heat exposure

If the core temperature rises above 37°C, the core temperature sensors in the brain signal this increase. This has several effects that produce results opposite to those described for a fall in core temperature. The brain now sends messages to the blood vessels in the skin causing them to dilate (have a larger diameter). More blood carrying heat from the core is brought to the surface outside the insulating fat layer. The blood is cooled by heat loss to the environment.

If the core is not sufficiently cooled, sweat glands in the skin are activated so that the skin surface is moistened. Evaporation of the sweat cools the blood.

The nerve signals from the heat sensors in the skin cause us to have a sensation of being hot. As a result, we may make behavioural changes like seeking the shade, reducing clothing, turning on a fan and reducing muscular activity to a minimum.

In certain animals evaporative cooling from the respiratory tract is also increased by panting when the core temperature rises.