Is it hot in here? Thermoregulation and homeostasis through an exercise activity.

HOMEOSTASIS, the control of an internal environment to maintain stable, relatively constant conditions, is a key concept in physiology (1). In endothermic species, including humans (Homo sapiens), the control of body temperature is fundamental to the control of a suitable internal environment. To help regulate core body temperature, the body has a number of different responses. For example, under warm conditions by initiating processes such as peripheral vasodilation and sweating, heat is dissipated via the skin’s surface to maintain a constant core temperature. This activity seeks to illustrate the difference between thermal perception (how warm or cold individuals “feel”) and core body temperature by monitoring changes in both during exercise. Using exercise, the activity can change thermal perception quickly, although core temperature will remain relatively stable. While homeostasis remains a core theme in physiology, many aspects of it are difficult to illustrate in a noninvasive activity (e.g., ion concentrations). Temperature can be more easily manipulated to demonstrate the concept, and the presence of the carotid artery, just behind the ear, ensures that core body temperature is easy to measure. This activity was developed for use in The Physiological Society’s stand at the Big Bang Fair, a science festival that attracts 50,000 school children and families over 4 days. Subsequently, it was adapted for use at the Cheltenham Science Festival and public activities at the International Union of Physiological Sciences Congress (in Birmingham, United Kingdom) for a wider public audience. This activity seeks to provide, in an informal environment, four key learning objectives for participants and observers. At the end of the activity, participants should be able to 1) describe their results and state whether they met their predictions before the activity, 2) compare the variability of skin surface temperature and temperature perception with that of core body temperature, 3) explain why core body temperature must be kept relatively constant, and 4) Explain the physiological mechanisms used by the body to maintain a relatively constant core body temperature.