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10 Cards in this Set
- Front
- Back
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How is an image formed on the retina
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cornea and lens responsible for refraction of light on retina
most refraction from cornea, but lens is adjustable ciliary muscle responsible for changing lens, contraction of muscle reduces tension on lens |
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How does light become an electrical signal
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stimulated photoreceptor causes HYPERpolarization, not depolarization due to no AP needed
this hyperpolarization causes a decrease in the number of open cGMP channels |
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How does the retina detect differences in luminance
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On-center vs. off center ganglion
On-center: light produces a burst of AP, darkness reduces discharge Off-center: light reduces rate of discharge, darkness bring a burst of AP the two types overall all over retina |
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Rod characteristics
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very sensitive to light, in low light only rods activated
low spatial resolution many more rods than cones in retina |
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Cone characteristics
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high spatial resolution, low light sensitivity
100 photons of light needed to produce a response very adaptable over varying light conditions |
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What is sound
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pressure waves that vibrate air
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What is the pathway for sound from the pinna of the ear to the primary auditory cortex on the superior temporal gyrus
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external and middle ear collect sound waves and amplify pressure
inner ear, fluid filled cochlea motion of the wave displaces hair cells travels thru auditory nerve and into 3 parts of cochlear nucleus: anteroventral, posterioventral, and dorsal |
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How does the cochlea of the inner ear discriminate various frequencies of sound
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the cochlea is wider and stiffer at its opening, narrower and more flexible at its end
each area of the cochlea responds more intensely to a specific frequency |
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How do sound waves become electrical signals
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stereocilia surround a single longer hair fiber
tip links that connect the stereocilia are displaced in parallel movement towards the tallest stereocilia, opening channels and depolarizing hair cell opposite movement closes them, and hyperpolarizes |
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What are the major causes of acquired deafness
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acoustical trauma: rupture of the tympanic membrane
ototoxic drugs: can affect hair cells presbyacusis: aging, atherosclerotic damage to vasculature of inner ear, hair cell damage Infection: scar tissue, stretching of tympanic membrane |
