In the negative feedback control system of the papillary lig

In the negative feedback control system of the papillary light reflex, what are the physiological processes that represent what engineers call the controller, plant, feedback element, controlling, controlled, feedback variables?

Solution

EdingerWestphal nuclei of brain (controller) lead to change in neural traffic down the efferent nerves back to the eyes (controller action). It affects the plant retina by feedback sensors sphincter muscles and radial dilator muscles which relax and contract respectively. The output is increase in pupil area.