If your blood temperature drop a 10th of a degree on a cold day, and I cause the adrenal glands and the pituitary to make sure the liver releases more blood sugar as fuel for muscles, which are the main furnaces of the body. I get you to start shivering so that heat will be produced by muscle activity. Sweat glands also shut down, detouring blood from body surfaces where it would become further chilled. If you are chilled enough, though, surface blood vessels will almost entirely shut down - and you will turn blue. I do one thing which is rather pointless when you are cold : I give you gooseflesh. This is a hangover from your furry ancestors. For them I used to tighten skin muscles to make their hair stand on end; it produced better insulation that way.
Tags: Hypothalamus, job of hypothalamus, role of hypothalamus