Answer:
Body temperature is monitored and controlled by the thermoregulatory centre in the brain. This centre has receptors sensitive to the temperature of the blood flowing through the brain. If the core body temperature is too high, the thermoregulatory centre causes the blood vessels supplying the skin capillaries to expand so that more blood flows through them. Since the blood flows through the entire body, it can take the excess heat from the core of the body to the skin, where it can be lost. When a blood vessel of any sort increases in diameter, we say that it dilates. Because the dilation is related to the vascular (blood) system, this process is called vasodilation.
