what is a pupillary reflex
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Pupillary light reflex The pupillary light reflex (PLR) 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 eye, thereby assisting in adaptation to various levels of lightness/darkness.he pupillary reflex pathway begins with the photosensitive retinal ganglion cells, which convey information to the optic nerve (via the optic disc). The optic nerve connects to the pretectal nucleus of the upper midbrain, bypassing the lateral geniculate nucleus and the primary visual cortex.
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Iris sphincter muscle In humans, it functions to constrict the pupil in bright light (pupillary light reflex) or during accommodation. [citation needed] In lower animals, the muscle cells themselves are photosensitive causing iris action without brain input. Innervation
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What is the Pupil of the Eye? - Definition & Function The whole job of the iris and pupil is to control the amount of light that gets into the eye. It's called a pupillary reflex, and you have probably noticed that a person's pupils are smaller in bright light and bigger in low light.This is your pupil controlling the amount of light that goes through the clear lens of your eyes to the retina in the back of your eye.he pupil of the eye is the black circle in the center of your iris. The iris is the colored ring in your eye whose color and structure is as individual as you are. From the outside of the eye, light passes through the clear lens, then through the hole that is the pupil.
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Pupillary Responses (CN II, III) In an afferent pupillary defect there is a decreased direct response caused by decreased visual function in one eye. This can be demonstrated with the swinging flashlight test, in which the light is moved back and forth between the eyes every two to three seconds. The afferent pupillary defect becomes obvious when the flashlight is moved from the normal to the affected eye, and the affected pupil dilates in response to light. Under normal conditions, the pupil constricts in response to light.
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- A stretch reflex, also referred to as a deep tendon reflex or myotatic stretch reflex, is a physical response to the extension of a muscle. In essence, it is a process that causes a contraction, thereby stopping a stretch.he stretch reflex prevents people from overextending their muscles. Protective response is what prevents muscles from being stretched too far. Before a workout, take time to gently and slowly stretch the muscles in order to help prevent any muscle damage.
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H-reflex The H-reflex (or Hoffmann's reflex) is a reflectory reaction of muscles after electrical stimulation of sensory fibers (Ia afferents stemming from muscle spindles) in their innervating nerves (for example, those located behind the knee).
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Mydriasis Mydriasis (/mᵻˈdraɪ.əsɪs/) is the dilation of the pupil, usually defined as when having a non-physiological cause, but sometimes defined as potentially being a physiological pupillary response. Non-physiological causes of mydriasis include disease, trauma, or the use of drugs. Normally, as part of the pupillary light reflex, the pupil dilates in the dark and constricts in the light to respectively improve vividity at night and to protect the retina from sunlight damage during the day.
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Startle response In animals, including humans, the startle response is a largely unconscious defensive response to sudden or threatening stimuli, such as sudden noise or sharp movement, and is associated with negative affect.[1] Usually the onset of the startle response is a startle reflex reaction. The startle reflex is a brainstem reflectory reaction (reflex) that serves to protect vulnerable parts, such as the back of the neck (whole-body startle) and the eyes (eyeblink) and facilitates escape from sudden stimuli.
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Digital single-lens reflex camera A digital single-lens reflex camera is a digital camera that combines the optics and the mechanisms of a single-lens reflex camera with a digital imaging sensor, as opposed to photographic film. The reflex design scheme is the primary difference between a DSLR and other digital cameras. In the reflex design, light travels through the lens, then to a mirror that alternates to send the image to either the viewfinder or the image sensor. The traditional alternative would be to have a viewfinder wit
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- Follow Us On: A reflex is an involuntary motor response to a sensory stimulus. For example when a light shines into your eyes, your pupils should get smaller very quickly, or when there is a loud, sudden, unexpected sound nearby, you startle.Reflexes perform many jobs for our central nervous system.ollow Us On: A reflex is an involuntary motor response to a sensory stimulus. For example when a light shines into your eyes, your pupils should get smaller very quickly, or when there is a loud, sudden, unexpected sound nearby, you startle.
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Response of the pupil ? 1 The pupillary light reflex is the reduction of pupil size in response to light. 2  The pupillary accommodation reflex is the reduction of pupil size in response to an object coming close to the eye.
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- 2. any reflex involving the iris, resulting in change in the size of the pupil, occurring in response to various stimuli, e.g., change in illumination or point of fixation, sudden loud noise, or emotional stimulation. quadriceps reflex knee jerk. quadrupedal extensor reflex Brain's reflex.
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Mydriasis (Redirected from Blown pupil) Mydriasis (/mᵻˈdraɪ.əsɪs/) is the dilation of the pupil, usually defined as when having a non-physiological cause, but sometimes defined as potentially being a physiological pupillary response. Non-physiological causes of mydriasis include disease, trauma, or the use of drugs.
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- Noun. 1. pupillary reflex-reflex contraction of the sphincter muscle of the iris in response to a bright light (or certain drugs) causing the pupil to become smaller. light reflex, miosis, myosis.
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- Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve. This response results in either. Abnormally constricted or “pinpoint” pupils are a great finding for our rapid diagnosis series.
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reflex 1. contraction of the pupil on exposure of the retina to light. 2. any reflex involving the iris, resulting in change in the size of the pupil, occurring in response to various stimuli, e.g., change in illumination or point of fixation, sudden loud noise, or emotional stimulation. quadriceps reflex knee jerk.
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Pupillary Responses (CN II, III) Pupillary Responses (CN II, III). First, record the pupil size and shape at rest. Next, note the direct response, meaning constriction of the illuminated pupil, as well as the consensual response, meaning constriction of the opposite pupil.
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Top 20 Doctor insights on: How Long Does Cough Associated With Roseola Last The cough reflex is a protective mechanism that uses muscles in your throat and chest to expel mucous and saliva that may contain pathogens that would otherwise possibly be inhaled via aerosol or to expel pathogens infecting the throat and respiratory system.
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- The corneal reflex is driven by the autonomic nervous system and is not controlled by the human desire/thought process. This means that the spasm/ corneal reflex is involuntary, and will occur no matter how much a person is trying not to. The corneal reflex is a good method of determining if a patient is “faking” a seizure or not.
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Pupillary reflex Pupillary reflex. In medicine, there are two pupillary reflexes 1  -. The pupillary light reflex is the reduction of pupil size in response to light. 2  The pupillary accommodation reflex is the reduction of pupil size in response to an object coming close to the eye.he optic nerve is responsible for the afferent limb of the pupillary reflex, or in other words, senses the incoming light. The oculomotor nerve is responsible for the efferent limb of the pupillary reflex; in other words, it drives the muscles that constrict the pupil.
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- 1 What it assesses-the integrity of the pupillary light reflex pathway. 2  How to perform it-dim the ambient light and ask the patient to fixate a distant target. 3  Illuminate the right eye from the right side and the left from the left side.here are essentially three reflexes to specifically test for: Light reflex test. 1  What it assesses-the integrity of the pupillary light reflex pathway. 2  How to perform it-dim the ambient light and ask the patient to fixate a distant target.
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- Purpose. A reflex is a simple nerve circuit. A stimulus, such as a light tap with a rubber hammer, causes sensory neurons (nerve cells) to send signals to the spinal cord. Here, the signals are conveyed both to the brain and to nerves that control muscles affected by the stimulus.
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Pupil The iris is a contractile structure, consisting mainly of smooth muscle, surrounding the pupil. Light enters the eye through the pupil, and the iris regulates the amount of light by controlling the size of the pupil. The iris contains two groups of smooth muscles; a circular group called the sphincter pupillae, and a radial group called the dilator pupillae.
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Chapter 8 - Reflex evaluation In this chapter we will discuss the evaluation of commonly tested reflexes of the spinal cord. We have previously considered reflexes involving the cranial nerves such as the pupillary light reflex, the jaw-jerk reflex, the baroreceptor reflex and gag.n this chapter we will discuss the evaluation of commonly tested reflexes of the spinal cord. We have previously considered reflexes involving the cranial nerves such as the pupillary light reflex, the jaw-jerk reflex, the baroreceptor reflex and gag.
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reflex reflex. a reflected involuntary action or movement; the sum total of any particular automatic response mediated by the nervous system. A reflex is built into the nervous system and does not need the intervention of conscious thought to take effect. positive reaction is a sharp contraction of the muscle of which the tendon is part. The patellar reflex is the best known of these reflexes. Absence indicates a defect in the reflex arc, an exaggerated response suggests an upper motor neuron lesion. Called also myotactic reflex.
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corneal reflex corneal reflex, a protective mechanism for the eye in which the eyelids close when the cornea is touched. This reflex is mediated by the ophthalmic division of the fifth cranial nerve (sensory) and seventh cranial nerve (motor) and may be used as a test of integrity of those nerves.