Final answer:
The consensual reflex of the pupils is an autonomic response to bright light where both pupils constrict to protect the retina and is controlled by the central nervous system.
Step-by-step explanation:
The consensual reflex of the pupils, also known as the pupillary light reflex, is a response to bright light hitting the retina. When light is detected, it triggers a sensory signal to travel along the optic nerve.
The signal then induces a parasympathetic reaction, which is mediated through the oculomotor nerve, then to the postganglionic fibers from the ciliary ganglion, and ultimately stimulates the circular fibers of the iris to constrict the pupil, hence reducing the amount of light entering the eyes.
This reflex is crucial for protecting the retina from excessive light that might cause damage. It is an autonomic response, different from somatic reflexes (like pulling back a hand from a hot surface), since the response involves both eyes, regardless of which eye is exposed to the light stimulus.
This indicates the central control of the autonomic system by the hypothalamus and other CNS locations, rather than a localized response.
When ambient light levels are low, the sympathetic nervous system takes charge and the pupils dilate, which is the opposing reflex, to allow more light to enter and improve vision under these conditions.