If body temperature is too high some blood vessels increase in size and sweat glands will excrete sweat resulting in a lower body temperature these changes are an example of

The answer is - Homeostasis

The human body has the ability to maintain a constant internal environment so that every organ function properly. Maintenance of a constant internal conditions is called homeostasis. For examples, a healthy human body functions optimum at normal temperature which is 37°C. If the body temperature increases well above 37°C, then by self-regulatory process, our body brings down temperature to the normal. This is homeostasis.