Sweat glands secrete sweat onto the surface of the skin. The sweat then evaporates, and creates a cooling effect, lowering the body s temperature. Skin arterioles and shunt vessels carry blood near the surface of the skin so that some of the body heat can be released. When vasodilation happens, or when stroke volume and heart rate increase upon exercise, more blood can pass near the surface of the skin to release heat. Shivering is an involuntary contraction of the muscles which releases heat in the contraction and warms up the body.
Hormones can also dictate body temperature.
Metabolic hormones can speed up the rate of metabolism, and thus heat the body, or they can slow the metabolism to produce less energy to try to cool the body. The hypothalamus, anterior pituitary, and thyroid all form a hormonal feedback loop which controls the metabolism. This in turn stimulates the thyroid to secrete the hormone thyroxin, which controls metabolism. It also acts as an inhibitor to the release of TRH from the hypothalamus. Thirst - there are osmoreceptors in the hypothalamus that can tell when cells in the body are losing water to their surroundings.