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Depending on the intensity of surrounding light, the iris makes an "automatic" adjustment to ensure that the retina receives the correct amount of light. This is another example of a protective reflex; too much light could damage the eye or give an excessively bright image, and too little light would result in an indistinct image.
The iris is a circular disc containing the pigment melanin, which prevents light from passing through, in the middle of which is a hole called the pupil. It contains 2 sorts of muscles:
Radial muscles are attached to the eye at the outside edge of the iris, radiating out like spokes of a wheel.
Circular muscles act like a series of rings around the pupil.
These 2 types of muscles are antagonistic, i.e. only one works at any one time:
Contraction of the radial muscles opens the pupil, allowing more light through, and contraction of the circular muscles closes the pupil, allowing less light through.
What else can I help you with?
What part of in pupil reflex for stimulus?
The stimulus in the pupil reflex would be light
What part in pupil reflex of coordinator?
The pupil reflex, specifically the pupillary light reflex, involves coordination between the optic nerve (cranial nerve II) and the oculomotor nerve (cranial nerve III). When light is shone in one eye, the optic nerve transmits signals to the brain, which then sends motor signals through the oculomotor nerve to constrict the pupil of both the illuminated eye and the other eye (consensual reflex). This reflex helps regulate the amount of light entering the eye and protects the retina from excessive illumination.
What does the ciliospinal reflex do to the pupil of the eye?
The pupil dilates when stimulated by the pinching on the nape of the neck.
Is a pupil autonomic reflex?
yes
What is the consensual reflex of the pupil?
The consensual reflex of the pupil is the simultaneous constriction of the pupil in both eyes when light is shone into one eye. This reflex is controlled by the autonomic nervous system to regulate the amount of light entering the eye and protect the retina.
What part of brain controls pupil dilation?
Edinger-Westphal nucleus of the brainstem controls the pupil reflex. An ER doctor who looks at the response to a pen light is checking on brain stem activity.
Which cranial nerve in responsible for the reflex constriction of the pupil in response to light and accomodation?
The oculomotor nerve (cranial nerve III) is responsible for the reflex constriction of the pupil in response to light and accommodation.
Where are the reflexes such as blinking and pupil reflex centered at?
Reflexes such as blinking and pupil reflex are centered in the brainstem. The trigeminal nerve is responsible for the blinking reflex, while the pupillary reflex is controlled by the oculomotor nerve. These reflexes help protect the eyes from harm and regulate the amount of light entering the eye.
How is pupil reflex controlled?
The pupil reflex is controlled by the autonomic nervous system, specifically the parasympathetic and sympathetic divisions. Constriction of the pupil (miosis) is controlled by the parasympathetic system through the action of the cranial nerve III (oculomotor nerve). Dilation of the pupil (mydriasis) is controlled by the sympathetic system through the action of the superior cervical ganglion.
Is the pupil a reflex or voluntary?
Pupils reacts to light, narrowing in bright light and widening in poor light - so is a reflex action.
Is the response of your pupil a reflex or a voluntary action?
The constriction of pupils in response to bright light is called the pupillary light reflex. If the light is shining directly into one eye, then the pupil in that eye will constrict (a direct response), but so will the pupil in the non-illuminated eye (a consensual response).This reflex involves two cranial nerves: the optic nerve, which senses the light, and the oculomotor nerve, which constricts both pupils. It is considered involuntary since you don't think about it.
What is a list of ten involuntary movements?
Sneezing, coughing, heart racing, peristalsis, pupil contraction, shivering, eructation, flatulence, patellar reflex, Babinsky reflex.
