Death in a hot tub: The physics of heat stroke

High environmental temperature and/or vigorous physical work will tend to cause a person’s body temperature to rise. In an attempt to maintain a normal body temperature of 37°C the body then increases its rate of dissipation of heat by mechanisms that involve large increases in the blood flow to the skin. When there is an increase in the fraction of the blood that flows to the skin, the fraction available to other organs will decrease. A decreased flow to the brain can cause unconsciousness or death. The basic elements of this competition can be represented in terms of a simple dc circuit. Here is an example where the elements of dc circuit theory can be coupled with basic concepts of thermodynamics to help demonstrate the complimentarity of different branches of physics and to help students in elementary physics courses to gain an improved understanding of an important physiological situation. Examples of this type seem to be absent from many of our texts for introductory courses in physics.