how does blood help to maintain  constant body temperature??

The blood distributes heat through out the body. When the body temperature is too high the hypothalamus sends an impulse to the blood vessels to the skin to dilate. The blood vessels then carry more blood (water) to the sweat glands to produce more sweat and because the superficial blood vessels are wider more heat is lost through radiation and conduction. When environmental temp drops the blood vessels in the skin constrict to supply less water to the sweat glands and less heat is lost through radiation and conduction.

Thumsb up please