Explain two ways in which the human body reacts to an increase in body temperature above the optimum.

Firstly sweat is released from sweat glands onto the surface of our skin. This acts to decrease body temperature by causing thermal engery to be transfered away from the skin as the sweat evaporates.

Secondly erector pillae muscles within the skin will relax causing hairs on the body to lie flat, preventing a layer of warm insulating air from being trapped, increasing heat loss and thus decreasing body temperature.