The thermoneutral zone is defined as: the region of the body halfway between the high-temperature core and the low-temperature skin. the environmental temperature range in which shivering, changes in blood flow, and changes in thyroid hormone concentrations can maintain homeostasis of the body's core temperature. the core body temperature at which no energy is expended to maintain homeostasis. the environmental temperature range over which the changes in skin blood flow alone can regulate body temperature. the region in the central core of the body where temperature never changes.