pupillary reflex

pupillary reflex
pupillary reflex n the contraction of the pupil in response to light entering the eye

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the reflex change in the size of the pupil according to the amount of light entering the eye. Bright light reaching the retina stimulates nerves of the parasympathetic nervous system, which cause the pupil to contract. In dim light the pupil opens, due to stimulation of the sympathetic nervous system. See also iris.

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1. contraction of the pupil on exposure of the retina to light. Called also light r. and pupillary light r. 2. any reflex involving the iris, changing the size of the pupil in response to a stimulus, e.g., change in illumination, change in point of fixation, sudden loud noise, or emotional stimulus.

Medical dictionary. 2011.

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Look at other dictionaries:

  • Pupillary reflex — refers to one of the reflexes associated with pupillary function. Types include: Pupillary light reflex Accommodation reflex Although pupillary dilation is not usually called a reflex , it is still usually considered a part of this topic.… …   Wikipedia

  • pupillary reflex — noun reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller • Syn: ↑light reflex, ↑miosis, ↑myosis • Derivationally related forms: ↑myotic (for: ↑myosis), ↑ …   Useful english dictionary

  • pupillary reflex — light reflex the reflex change in the size of the pupil according to the amount of light entering the eye. Bright light reaching the retina stimulates nerves of the parasympathetic nervous system, which cause the pupil to contract. In dim light… …   The new mediacal dictionary

  • Westphal phenomenon pupillary reflex — West·phal phenomenon, pupillary reflex (vestґfahl) [Alexander Karl Otto Westphal, German neurologist, 1863–1941] orbicularis pupillary reflex …   Medical dictionary

  • reversed pupillary reflex — any abnormal pupillary reflex opposite to one that occurs normally, such as dilation of the pupil when the retina is stimulated by light. Called also paradoxical pupillary r. or phenomenon …   Medical dictionary

  • Pupillary response — or dilation of the pupil is a physiological response that varies the size of the pupil of the eye via the iris dilator muscle. It can have a variety of causes. It may be an involuntary reflex reaction to exposure to light. Or it may indicate… …   Wikipedia

  • Westphal pupillary reflex — Westphal Piltz reflex orbicularis pupillary r …   Medical dictionary

  • orbicularis pupillary reflex — unilateral contraction of the pupil, followed by dilatation after closure or attempted closure of eyelids that are forcibly held apart. Called also Galassi pupillary, orbicularis, or Westphal Piltz phenomenon and Gifford, Gifford Galassi, or… …   Medical dictionary

  • paradoxical pupillary reflex — 1. reversed pupillary r. 2. dilatation of the pupil on exposure to light; sometimes seen in conditions such as tabes dorsalis. Called also Bekhterev r. and paradoxical pupillary phenomenon …   Medical dictionary

  • РЕФЛЕКС ЗРАЧКОВЫЙ (PUPILLARY REFLEX), РЕФЛЕКС СВЕТОВОЙ — (light reflex) рефлекс, приводящий к изменению размеров зрачка в зависимости от количества попадающего в глаз света. Так, при попадании на сетчатку яркого света возбуждаются парасимпатические нервы, что приводит к сужению зрачка. При тусклом… …   Толковый словарь по медицине

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