Pupillary diameter, or more precisely iris size, is controlled by two muscles, the sphincter pupillae, which is primarily under the control of the parasympathetic nervous system, and the dilator pupillae, which is primarily under the control of the sympathetic nervous system.
What part of the nervous system controls the pupillary reflex?
The parasympathetic nervous system is the main system responsible for pupil constriction in response to light. The integrated afferent input is transmitted along the axons of the retinal ganglion cells (RGC), which contribute to the optic nerve.
How do the different nervous systems work together to influence a pupillary response?
Pupillary Reflex Pathways. The pupil is under competing autonomic control in response to light levels hitting the retina. The sympathetic system will dilate the pupil when the retina is not receiving enough light, and the parasympathetic system will constrict the pupil when too much light hits the retina.
How does nervous system affect behavior?
Your nervous system guides almost everything you do, think, say or feel. It controls complicated processes like movement, thought and memory. It also plays an essential role in the things your body does without thinking, such as breathing, blushing and blinking.
Which is more important endocrine or nervous system?
A quick-acting nervous system is essential for immediate activation of the adrenal glands, while the endocrine system mobilizes the body for action. The male sex glands, known as the testes, secrete a number of hormones, the most important of which is testosterone, the male sex hormone.
Why do both pupils constrict in response to light?
Illumination of one eye causes reflexive constriction of both pupils: via the direct and indirect pupillary light reflexes. … Fibres from these nuclei travel with the oculomotor (III) nerves to innervate the ciliary ganglia, which supply the sphincter pupillae muscles (causing both pupils to constrict).
Why do we check pupil response?
Pupillary assessment is an important part of neurological assessment because changes in the size, equality and reactivity of the pupils can provide vital diagnostic information in the critically ill patient (Smith, 2003). Both pupils should be the same shape, size and react equally to light.