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101 Cards in this Set
- Front
- Back
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Innermost Tunic of Eye |
Retina |
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Retina is made up of what type of tissue? |
Neural tissue |
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The Neural Tissue of retina is composed of two types of Photoreceptors? |
Rod Cones |
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Rods |
Photoreceptors that allow for black and white vision |
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Cones |
Photoreceptors for color vision
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Photoreceptors convert light energy to what? |
Nerve impulses |
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What type of energy is light? |
Radiant |
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What happens to the nerve impulses sent from the ganglion cells of the retina? |
they are transmitted to the optic cortex resulting in visual perception |
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What is the blind spot of the eye composed of? |
Axons of ganglion cells, it lacks photoreceptors |
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What is the Optic Chiasm? |
Area where fibers from the medial retina from each eye cross over to opposite side and lateral fibers of eyes remain on the same side |
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Blind Spot is also known as what? |
Optic Disc
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Optic tract |
extends form the optic chiasm to the Lateral Geniculate Body of the Thalamus |
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Visual Pathway |
Retina Optic nerve Optic Chiasm Optic Tracts Lateral geniculate body of Thalamus Terminates in the visual cortex occipital lobe
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Where is the visual Cortex? |
Occipital lobe
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Where is the Lateral Geniculate Body? |
Thalamus |
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Each eye receives light from where? |
both right and left hemifields
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What happens when light passes from one medium to another? |
speed of transmission changes and rays are bent or refracted (spoon in water) |
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Refracted |
bent |
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Does light travel faster through air or water? |
air |
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What happens to light rays as they pass through the cornea, lens and vitreous humor? |
they are slowed and refracted |
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Does the vitreous humor or cornea refraction index vary? |
no, it remains constant
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The lens refraction index varies based on what? |
shape of lens |
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Greater the convexity or bulge means more or less refraction? |
More refraction |
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When does the lens need to change convexity for near or far objects? |
NEAR |
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How does the lens change shape? |
Contraction of ciliary body decreasing tension on suspensory ligaments and this relaxation causes bulge of lens |
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Accommodation |
adjustments that lead to plumping or increased convexity of the lens |
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What are the intrinsic eye muscles ? |
Ciliary body and Iris |
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Ciliary body |
smooth intrinsic eye muscle responsible for shape of lens |
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Iris |
Smooth intrinsic eye muscle responsible for the size of pupil |
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Extrinsic Eye muscles |
skeletal muscles attached to outside of the eye and are responsible for eye movement controlling focus on fovea centralis
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Fovea Centralis |
most dense with cones photoreceptors, sharpest vision
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What is responsible for convergence? |
extrinsic eye muscles (skeletal) |
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Covergence |
medial eye movement, allows tracking of object for near vision |
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Visual Acuity |
sharpest vision |
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Snellen Eye test |
Chart consisting of letter of various size, can be distinguished by normal vision at specific distance |
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Astigmatism |
condition of unequal curvature of cornea or lens |
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How does astigmatism affect vision? |
prevents light rays from being focused with equal sharpness on retina
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Test for astigmatism |
Chart consisting of circle in center and lines radiating form there around in a circle
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Astigmatism would be marked by? |
Blurred vision |
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Color vision relays on the degree of impulses by what 3 receptors? |
Cones: red Blue Green |
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Is colorblindness more common in men or women, Why? |
Men Cones are coded for on x chromosome female redundancy helps prevent errors |
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What is the most common type of color blindness? |
Red and Green colorblindness |
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What causes red and Green colorblindness? |
deficit in cones stimulated by green or red light |
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What color would one see if they had complete colorblindness? |
Shades of Gray |
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How to the eyes actually view the image of the world? |
upside down and the brain flips it |
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Lens convexity is flatter to see closer or further objects? |
Further |
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What 3 things are needed to see close objects? |
Accommodation Convergence constriction of pupil |
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Why does the pupil need to be constricted to focus on near objects? |
Focus the light on the Fovea Centralis
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What would happen to Vision if there was a lesion a optic nerve? |
Blindness in the eye with the nerve |
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What would happen to vision if there was a lesion in the optic chiasm? |
Tunnel vision, loss of peripheral vision |
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What would happen to vision if there was a lesion at the optic tract? |
Left: Loss of left medial, and Right peripheral
Right: loss of Right medial, and left peripheral |
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Blind Spot Test |
find optic disc as you slowly move image towards you when you lose sight of object next to focus |
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Near point accommodation |
test for near point by moving letter towards eye until blurry |
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Near point |
closest distance one can see an object in sharp focus |
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Why does near point increase with age? |
The lens begins to lose flexibility and the ciliary body can lose strength |
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Eye reflexes test |
test for 3 requirements for near vision 1. Accommodation 2. Convergence 3. Constriction of pupils |
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What does 20/20 mean? |
using one eye a person with normal vision can read at 20 feet away |
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So is 20/ 15 better or worse than 20/20? |
Better you can read what someone with good vision can read at 15ft from 20ft or further away |
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Color Blindness Test |
can you see colors from 30 inches using Ishihara plates |
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Mechanism of hearing |
sound waves through external auditory canal tympanic membrane ossicles (incus, malleus, stapes) oval window Inner ear (fluid filled cochlea) |
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Travel of sound in inner ear |
oval window to fluid filled cochlea vestibular duct to tympani duct Vibrate basilar membrane, stereocilia bends at tectorial membrane (endolymph Organ of Corti) Transmits to neural signals by depolarizing auditory center
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Hearing |
neural perception of sound |
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Where is the auditory center in brain? |
Temporal lobe
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What occurs once the sound travels to the mechanoreceptors in the Organ of Corti? |
they are stimulated by a sounds of various frequencies and amplitude and the depolarize beginning a chain of nerve impulses through cochlear nerve to auditory centers |
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Tone or pitch is determined by what? |
specific receptors based on frequency of vibrations and part of brain that receives it
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High frequency is noted by what? |
High pitch sound detected by oval window
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Low frequency waves are noted by what? |
Low pitch sound detected by the apex of the cochlea |
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Frequency of waves means what? |
How many waves occur or speed of waves
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Amplitude determine what? |
Loudness |
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What determines amplitude or loudness of waves? |
intensity or strength of wave |
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Conduction Deafness |
blockage of waves reaching the inner ear |
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What test can test for Conduction deafness? |
Rhinne Weber
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Is Conduction deafness reversible? |
Yes, surgery or hearing aids can help
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Sensoneural deafness |
Nerve deafness
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Is nerve deafness reversible? |
No it is permanent
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What can cause nerve deafness? |
damage to sound receptors or neurons that send impulse to brain, can result form loud sounds
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Rhinne test |
test for conduction deafness using tuning fork and comparing bone conduction vs air conduction
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Positive Rhinne test |
Conduction deafness if Air Conduction < Bone Conduction |
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Negative Rhinne Test |
Air Conduction > Bone Conduction
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Weber Test |
detects differences between left and right ear simultaneously |
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Weber test if Conduction deafness is present |
Sound is louder in ear that is not covered |
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Weber test procedure |
tuning fork placed on top of middle of head, then cover one ear |
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Weber test indicating no deafness or damage |
plugged ear is louder |
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Where do you find apparatus for equilibrium? |
Inner ear |
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Dynamic Equilibrium |
spinning or rotation detected by the crista ampullaris containing hair cell with cupula |
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3 planes for Dynamic Equilibrium |
Frontal Horizontal Sagittal |
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Cupula |
Hair cell in the crista ampullaris covered in gelatinous cap responsible for creating an action potential if rotation or spinning occurs |
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How does the cupula signal that movement is occuring? |
The movement cause the surrounding endolymph in the canal to shift pushing cupula in opposite direction of movement and the bent hair cells create an action potential
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Which direction does the cupula bend as movement occurs and why? |
the opposite direction because the endolymph lags behind ( bucket with water moving quickly) |
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Nystagmus |
trailing of eyes slowly in one direction followed by rapid movement in opposite
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Is Nystagmus an indication of semicircular canals working properly or improperly? |
properly, this is normal and should occur |
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Barany Test |
test for Nystgamus and indicates function of semicircular canals |
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Static Equilibrium |
gravitational and linear changes
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What area of the inner ear is responsible for determining static equilibrium? |
Maculae in saccule and utricle |
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Mechanism for static equilibrium |
hair cells in each macula are embedded with otolithic membrane (Calcium carbonates aka otoliths); movement causes movement of otoliths |
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What are the 3 inputs for Equilibrium |
Proprioreceptors Vestibular input Visual Sensory Input
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Proprioreceptors
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send signals to vestibule nuclei about body position |
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Vestibular Input |
very helpful. but not essential for maintaining equilibrium |
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Visual input |
informs us of our orientation to the ground |
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Romberg Test |
test equilibrium and role vision plays in maintaining equilibrium |
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Romberg Procedure |
test equilibrium with eyes open Test equilibrium with one foot raised tst equilibrium with eyes closed |
