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Pupillary light reflex

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The pupillary light reflex (PLR) or photopupillary reflex is a reflex that controls the diameter of the pupil, in response to the intensity (luminance) of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation to various levels of lightness/darkness. [1]

44 relations: Adaptation (eye), Afferent nerve fiber, Attention, Axon, Barbiturate, Binocular rivalry, Brainstem, Brainstem death, Ciliary ganglion, Consensual response, Edinger–Westphal nucleus, Efferent nerve fiber, Emergency department, Eye, Hippus, Intrinsically photosensitive retinal ganglion cells, Iris (anatomy), Iris sphincter muscle, Lateral geniculate nucleus, Lesion, Luminance, Marcus Gunn pupil, Melanopsin, Midbrain, Miosis, Motor system, Mydriasis, Oculomotor nerve, Optic chiasm, Optic disc, Optic nerve, Oxford University Press, Pretectal area, Pupil, Pupillary response, Reflex, Retina, Retinal ganglion cell, Retinohypothalamic tract, Sensory nervous system, Slit lamp, Stimulus (physiology), Synapse, Visual cortex.

Adaptation (eye)

In ocular physiology, adaptation is the ability of the eye to adjust to various levels of light.

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Afferent nerve fiber

Afferent nerve fibers refer to axonal projections that arrive at a particular region; as opposed to efferent projections that exit the region.

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Attention

Attention, also referred to as enthrallment, is the behavioral and cognitive process of selectively concentrating on a discrete aspect of information, whether deemed subjective or objective, while ignoring other perceivable information.

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Axon

An axon (from Greek ἄξων áxōn, axis) or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that typically conducts electrical impulses known as action potentials, away from the nerve cell body.

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Barbiturate

A barbiturate is a drug that acts as a central nervous system depressant, and can therefore produce a wide spectrum of effects, from mild sedation to death.

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Binocular rivalry

Binocular rivalry is a phenomenon of visual perception in which perception alternates between different images presented to each eye.

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Brainstem

The brainstem (or brain stem) is the posterior part of the brain, adjoining and structurally continuous with the spinal cord.

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Brainstem death

Brainstem death is a clinical syndrome defined by the absence of reflexes with pathways through the brainstem—the "stalk" of the brain, which connects the spinal cord to the mid-brain, cerebellum and cerebral hemispheres—in a deeply comatose, ventilator-dependent patient.

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Christmas

Christmas is an annual festival commemorating the birth of Jesus Christ,Martindale, Cyril Charles.

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Christmas and holiday season

The Christmas season, also called the festive season, or the holiday season (mainly in the U.S. and Canada; often simply called the holidays),, is an annually recurring period recognized in many Western and Western-influenced countries that is generally considered to run from late November to early January.

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Christmas Eve

Christmas Eve is the evening or entire day before Christmas Day, the festival commemorating the birth of Jesus.

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Christmas traditions

Christmas traditions vary from country to country.

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Ciliary ganglion

The ciliary ganglion is a parasympathetic ganglion located just behind the eye in the posterior orbit.

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Consensual response

A consensual response is any reflex observed on one side of the body when the other side has been stimulated.

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Edinger–Westphal nucleus

The Edinger–Westphal nucleus (accessory oculomotor nucleus) is the parasympathetic pre-ganglionic nucleus that innervates the iris sphincter muscle and the ciliary muscle.

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Efferent nerve fiber

In the peripheral nervous system, an efferent nerve fiber is the axon of a motor neuron.

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Emergency department

An emergency department (ED), also known as an accident & emergency department (A&E), emergency room (ER), emergency ward (EW) or casualty department, is a medical treatment facility specializing in emergency medicine, the acute care of patients who present without prior appointment; either by their own means or by that of an ambulance.

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Eye

Eyes are organs of the visual system.

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Hippus

Hippus, also known as pupillary athetosis, is spasmodic, rhythmic, but regular dilating and contracting pupillary movements between the sphincter and dilator muscles.

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Intrinsically photosensitive retinal ganglion cells

Intrinsically photosensitive retinal ganglion cells (ipRGCs), also called photosensitive retinal ganglion cells (pRGC), or melanopsin-containing retinal ganglion cells (mRGCs), are a type of neuron in the retina of the mammalian eye.

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Iris (anatomy)

In humans and most mammals and birds, the iris (plural: irides or irises) is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupil and thus the amount of light reaching the retina.

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Iris sphincter muscle

The iris sphincter muscle (pupillary sphincter, pupillary constrictor, circular muscle of iris, circular fibers) is a muscle in the part of the eye called the iris.

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Lateral geniculate nucleus

The lateral geniculate nucleus (LGN; also called the lateral geniculate body or lateral geniculate complex) is a relay center in the thalamus for the visual pathway.

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Lesion

A lesion is any abnormal damage or change in the tissue of an organism, usually caused by disease or trauma.

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Luminance

Luminance is a photometric measure of the luminous intensity per unit area of light travelling in a given direction.

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Marcus Gunn pupil

Relative afferent pupillary defect (RAPD) or Marcus Gunn pupil is a medical sign observed during the swinging-flashlight test whereupon the patient's pupils constrict less (therefore appearing to dilate) when a bright light is swung from the unaffected eye to the affected eye.

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Melanopsin

Melanopsin is a type of photopigment belonging to a larger family of light-sensitive retinal proteins called opsins and encoded by the gene Opn4.

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Midbrain

The midbrain or mesencephalon (from Greek mesos 'middle', and enkephalos 'brain') is a portion of the central nervous system associated with vision, hearing, motor control, sleep/wake, arousal (alertness), and temperature regulation.

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Miosis

Miosis is excessive constriction of the pupil.

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Motor system

The motor system is the part of the central nervous system that is involved with movement.

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Mydriasis

Mydriasis is the dilation of the pupil, usually having a non-physiological cause, or sometimes a physiological pupillary response.

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New Year

New Year is the time or day at which a new calendar year begins and the calendar's year count increments by one.

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New Year's Day

New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar.

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New Year's Eve

In the Gregorian calendar, New Year's Eve (also known as Old Year's Day or Saint Sylvester's Day in many countries), the last day of the year, is on 31 December which is the seventh day of Christmastide.

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Oculomotor nerve

The oculomotor nerve is the third cranial nerve.

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Optic chiasm

The optic chiasm or optic chiasma (Greek χίασμα, "crossing", from the Greek χιάζω 'to mark with an X', after the Greek letter 'Χ', chi) is the part of the brain where the optic nerves partially cross.

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Optic disc

The optic disc or optic nerve head is the point of exit for ganglion cell axons leaving the eye.

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Optic nerve

The optic nerve, also known as cranial nerve II, is a paired nerve that transmits visual information from the retina to the brain.

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Oxford University Press

Oxford University Press (OUP) is the largest university press in the world, and the second oldest after Cambridge University Press.

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Pretectal area

The pretectal area, or pretectum, is a midbrain structure composed of seven nuclei and comprises part of the subcortical visual system.

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Pupil

The pupil is a hole located in the center of the iris of the eye that allows light to strike the retina.

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Pupillary response

Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve.

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Reflex

A reflex, or reflex action, is an involuntary and nearly instantaneous movement in response to a stimulus.

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Retina

The retina is the innermost, light-sensitive "coat", or layer, of shell tissue of the eye of most vertebrates and some molluscs.

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Retinal ganglion cell

A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the eye.

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Retinohypothalamic tract

The retinohypothalamic tract (RHT) is a photic neural input pathway involved in the circadian rhythms of mammals.

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Sensory nervous system

The sensory nervous system is a part of the nervous system responsible for processing sensory information.

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Slit lamp

The slit lamp is an instrument consisting of a high-intensity light source that can be focused to shine a thin sheet of light into the eye.

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Stimulus (physiology)

In physiology, a stimulus (plural stimuli) is a detectable change in the internal or external environment.

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Synapse

In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron or to the target efferent cell.

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Visual cortex

The visual cortex of the brain is a part of the cerebral cortex that processes visual information.

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2018

2018 has been designated as the third International Year of the Reef by the International Coral Reef Initiative.

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2019

2019 (MMXIX) will be a common year starting on Tuesday of the Gregorian calendar, the 2019th year of the Common Era (CE) and Anno Domini (AD) designations, the 19th year of the 3rd millennium, the 19th year of the 21st century, and the 10th and last year of the 2010s decade.

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References

[1] https://en.wikipedia.org/wiki/Pupillary_light_reflex

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