The body temperature of human beings is 37°C (98°F) which is constant. When the body temperature increases, the blood vessels of the skin dilates to increase peripheral flow of the blood. As a result, the heat radiates out. Simultaneously, the sweat glands activates to secrete more sweat that evaporates and further reduce the body temperature. Excess sweating causes loss of water and salts from the body which may cause dehydration. Hence, our kidneys absorb more water as a result concentrated urine is formed. On the contrary, when the body temperature decreases the skin blood vessels contracts to reduce peripheral blood flow and the heat loss is prevented. This process of temperature control is regulated by the hypothalamus part of the brain.
