Classical emotions

Another neurological approach distinguishes two classes of emotion: "classical" emotions such as love, anger and fear that are evoked by environmental stimuli via distance receptors in the eyes, nose and ears; and "homeostatic" (or "primordial" ) emotions – imperious (attention-demanding) feelings such as pain, hunger and fatigue, evoked by internal body states communicated to the central nervous system by interoceptors, that motivate behavior aimed at maintaining the body's internal milieu at its ideal state.

Derek Denton defines the latter as "the subjective element of the instincts, which are the genetically programmed behaviour patterns which contrive homeostasis. They include thirst, hunger for air, hunger for food, pain and hunger for specific minerals etc. There are two constituents of a primordial emotion--the specific sensation which when severe may be imperious, and the compelling intention for gratification by a consummatory act."