If your blood heats up as little as a 10th of a degree on a warm day, I go to work. I send messages to the pituitary gland and through the sympathetic nervous system to dilate surface blood vessels and open tens of thousands of sweat glands. The sweat cools the skin so as to get rid of the extra heat in your blood. At the same time I signal other brain areas to speed up breathing so that, you will pant - and thus carry away more heat.
Tags: Hypothalamus, job of hypothalamus, role of hypothalamus