Reflex action occurred in eye

[Primarygun]

Does the reflex action occurred in eye involve the cerebral cortex of the cerebrum?

There are many reflex actions, such as dilation and constriction of pupil...

[dttom]

As we can feel the dilation or contraction of the pupil(just for an example), I think the reflex actions of the eyes will finally enter out cerebral cortex(actually all of the explicit reflex actions in body will almost, eventually enter our cerebral cortex). But I'm not sure whether it enters the cortex directly or indirectly.

[Mokele]

The brain does not directly control the dilation or constriction of the pupil through nerves. Instead, hormones are secreted, such as adrenaline, which cause many effects throughout the body, including pupil dilation.

 

Mokele

[Primarygun]

Can you explain further? I don't know whether the nerve impulse passes through the cerebral cortex to the medulla oblongata.

[Glider]

Does the reflex action occurred in eye involve the cerebral cortex of the cerebrum?

There are many reflex actions' date=' such as dilation and constriction of pupil...[/quote']

No. Pupilliary reflex is under the control of the autonomic nervous system (ANS). The ANS consists of two sub-divisions; the sympathetic and parasympathetic divisions. These work in opposition to each other and exist in a kind of tonic balance.

 

The ANS is responsible for all somatic functions outside of conscious control, i.e. heart rate, digestion, renal and bladder function pupillary dilation/constriction etc..

 

The sympathetic division is responsible for processes requiring or preparing for energy use (preparing us for fight or flight). The parasympathetic division is responsible for 'stand down'; energy conserving processes.

 

In every day situations sympathetic activity results in pupillary dilation and parasympathetic activity in pupillary constriction.

 

However, in the case of pupillary reflex, as with all reflexes this is a function of a 'reflex arc'. A reflex arc is a functional system consisting of an afferent (sensory) pathway, an integrating system, usually interneurons at the spinal level, and an efferent (motor) pathway. As I said, this is a functional system that works at the spinal level and it does not involve the higher CNS (brain).

 

In the case of the eye, sudden bright light is detected by the sensory cells in the retina. The signals are transmitted to an integrating system (in this case in the brain stem), which relays signals straight back down the efferent (motor) pathway causing the pupil to constrict.

 

The purpose of reflex arcs is to generate the most rapid response to an aversive or potentially harmful stimulus. By arcing at the spinal level and thus cutting out the higher CNS they reduce the response time, thus limiting any damage exposure to harmful stimuli can do.

 

As the integrating system of the pupillary reflex is in the brain stem, medics use the pupillary reflex to test for brain stem damage.