Describe the roles of the nervous muscular circulatory and respiratory systems in heat regulation

The nervous system can detect the body temperature and will send signal to alter the body organ to act differently when body temperature too high or too low. 
Muscle contraction can produce heat, that is why when someone feeling cold they start shivering unconsciously. The nervous system detects the cold and tells the muscle to shiver to produce heat.
When temperature too high, the blood vessel in the skin will dilate to increase the rate of losing heat but it will constrict when the temperature too low.
The respiratory organ can also remove heat from the body so the respiratory rate can be increased if the body temperature too high.