We, along with other mammals and birds, are endotherms. We use thermoregulation to maintain a consistent internal body temperature – between 37C and 37.5C. When the external environment changes, “A range of physiological responses is initiated, including the reduction of tissue temperature – skin, blood and muscle,” says Dr Joseph Costello, exercise and environmental physiologist at Portsmouth University’s extreme environments laboratories. “If the exposure is over a longer period of time, you may also observe a reduction in deep body temperature.”
Thermoregulation is controlled by the hypothalamus, a structure deep in the brain that maintains internal balance – or homeostasis – by regulating processes such as heart rate and body temperature. If the hypothalamus senses the body growing cold, it sends signals to the skin, glands, muscles and organs, kickstarting responses that will keep the body warm and protect the vital organs.
