THERMOREGULATION IN MAMMALS

THERMOREGULATION IN MAMMALS
Over the course of their evolution, mammals have developed a sophisticated nervous system by which they can control their internal temperature. Thermoregulation allows mammals to keep their internal temperatures constant. This can occur despite external temperature changes in their environment. It offers mammals a degree of freedom from their environment. However, it requires a very large expenditure of energy. This process is centered within the hypothalamus. The hypothalamus is a part of the brain responsible for other subconscious functions like breathing and blinking. By using nervous signals sent from temperature-sensing nerves in the skin, the hypothalamus can activate mechanisms in the body to regulate the body’s internal temperature.   
The most basic process for temperature regulation is simply to change the rate of heat production. The hypothalamus sends signals to skeletal muscles, which causes them to move. This movement requires muscle cells to metabolize substances to produce energy and, in doing so, create heat. A mammal involuntarily shivers when it is cold because the hypothalamus is ordering the muscles to move and produce heat. Conversely, the hypothalamus can also stop unnecessary muscle movement and slow metabolic heat production to cool a mammal.