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neurophys > vision > Flashcards

vision Flashcards

1
Q

as objects come closer what happens to the lens

A

lens thickens and increases refraction

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2
Q

strength of lens defined by

A

diopters

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3
Q

cornea bends light by __ diopters

A

48

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4
Q

hyperopia

A

farsightness

eyeball too short

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5
Q

where is image formed in hyperopia

A

in back of fovea

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6
Q

hyperopia corrected by

A

convex lens

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7
Q

myopia

A

nearsightness

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8
Q

where is image formed in myopia

A

front of fovea

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9
Q

myopia corrected by

A

concave lens

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10
Q

astigmatism is

A

defect in cornea shape or lens shape

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11
Q

astigmatism corrected by

A

adding barrel shape to specific areas of lens

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12
Q

accommodation focuses image onto

A

fovea

suspensory ligaments attach elastic lens to circularly arranged ciliary muscles

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13
Q

focusing on far objects, lens becomes what

and what innervation

A

lens thinner
sympathetic innervation(beta) from ciliary ganglion inhibit ciliary muscle contraction
radial tension on suspensory ligaments increased
refraction less
pupil diameter wider

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14
Q

what happens during accommodation to near objects

A

ciliary muscles contract

relieve tension on suspensory ligaments

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15
Q

what innervation responsible for accommodation to near objects

A

parasympathetic

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16
Q

presbyopia is

A

impaired ability to focus on near objects

lens looses elasticity

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17
Q

pupil constriction limits

A

limits incoming light, reducing scatter of light

improves focus

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18
Q

in binocular vision

A

both eyes converge on object of interest

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19
Q

rods purpose is

A

detection of photons

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20
Q

where are rods found

A

lateral to fovea

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21
Q

cones purpose

A

detection of photons and mediation of visual acuity

22
Q

where are cones found

A

fovea centralis

23
Q

only ___ cells have action potentials

A

ganglion

24
Q

fovea is center of

A

macula

25
Q

___cells synapse with cones

A

horizontal

26
Q

___ cells synapse from rods to cone circuits

A

amacrine

27
Q

unstimulated photoreceptors are

A

depolarized

28
Q

vision operates ___ compared to other neural circuits

A

opposite

29
Q

photoreceptors depolarzed to

A

-40

30
Q

glutamate does what

A

metabotropically inibits on bipolar cells via mGluR6

iontropically stimulates off bipolar cells via AMPA and kainate receptors

31
Q

light sensitive portion of rhodopsin activates

A

G protein transducin which activates PDE

32
Q

gultamate release ceases as

A

Ca inside conc falls

33
Q

rhodopsin absorbs light at

A

505mm

34
Q

melanopsin function

A

detect darkness and release melatonin from pineal gland

35
Q

receptors synapse onto

A

bipolar cells

36
Q

presence of glutamate stimulates

A

off bipolar cells

37
Q

presence of GABA stimulates what

A

on center cells stimulate ganglion cells

38
Q

what is key elements involved in lateral inhibition circuits of retina

A

horizontal cells

39
Q

when stimulate horizontal cells release

A

GABA

40
Q

GABA does what

A

hyperpolarizes cones

41
Q

hyperpolarized cones do what

A

cease releasing glutamate

mediate detection of light

42
Q

GABA release from HC stops when

A

HC hyperpolarized aka unstimulated

43
Q

if photons strike only cones in off surround what happens to on center cones

A

become depolarized. glutamate release increased

off surround hyperpolarized

44
Q

off center ganglion cells wired to visual cortex to perceive

A

blackness

45
Q

lack of GABA from HCs stimulates

A

lateral inhibition mechanisms in retina

46
Q

visual cortex can process maximum of ___ images eper second

A

20-70

47
Q

shining light onto one pupil causes ___ constriction

A

ipsilateral/same side

48
Q

consensual light reflex demonstrated when

A

contralateral pupil also constricts

49
Q

absence of consensual light reflex in opposite pupil indicates

A

lesion in CN III

50
Q

ciliary reflex is stimulation of

A

sympathetic ANS division

Adelta fiber pain dilates pupil

neurophys (8 decks)

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