Homeostasis refers to the ability of the body to maintain a stable internal environment despite changes in the external environment. One way the body achieves homeostasis is through negative feedback loops.
A negative feedback loop occurs when a change in a variable triggers a response that counteracts the original change and returns the variable to its original set point. In regards to temperature regulation in humans, the set point is typically around 37°C (98.6°F).
An example of a negative feedback loop in regards to temperature regulation is when a person walks from the hot summer heat outside to a cold air-conditioned room inside. The change in temperature will trigger the body to respond in order to bring the internal temperature back to its set point. In this scenario, the hypothalamus in the brain senses the drop in body temperature and activates mechanisms to generate heat, such as increasing blood flow to the skin and inducing shivering. These responses work to counteract the initial change in temperature and return the body to its set point.