Various factors that can cross the blood-brain barrier, such as pyrogenic sources, act on the thermoregulatory point, causing it to change, resulting in an upward shift. The thermoregulatory centre then regulates the body’s temperature and increases the body’s metabolism through various factors or the uncontrolled movement of the skeletal muscles through the motor nerves (clinically manifested as chills), resulting in increased heat production; on the other hand, the increased excitation of the vegetative nerves reduces heat loss, with the end result that the body’s heat production is greater than the body’s heat loss, resulting in a rise in body temperature and fever.