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PHYSL 200 > Vision > Flashcards

Vision Flashcards

1
Q

what is the receptor for taste and smell

A

chemoreceptors

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2
Q

what is the receptor for pain

A

nociceptors

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3
Q

what is the receptor for hearing and balance

A

mechanoreceptors

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4
Q

what is the receptor for temperature

A

thermoreceptors

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5
Q

what is the receptor for vision

A

Photoreceptors

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6
Q

define sensory perception

A

deconstruction of external world and reconstruction of the internal representation

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7
Q

____ is when sensory endings respond to a particular type of energy applied to them

A

adequate stimulus

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8
Q

the conversion of energy into ____ is called

A

electrochemical , primary transduction

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9
Q

what are the two scenarios of primary transduction in the visual and hearing systems

A

visual - converting photos of light in to change in membrane potential
hearing - converting pressure waves to the bending of hair cells

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10
Q

what needs to happen if the generator potential is hyperpolarizing

A

K leaves the cell

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11
Q

the magnitude of the generator potential is proportional/inversely proportional to the strength of stimulus

A

proportional

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12
Q

true or false - generator potentials are usually depolarizing

A

true

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13
Q

humans can detect light with wavelengths between

a) 200-700nm
b) 390-700nm
c) 390-500nm

A

b

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14
Q

humans can distinguish ____ colors
a) million
b) billion
c) hundreds

A

a

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15
Q

the tough white fibrous part of the eye is

A

the sclera

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16
Q

what part of the eye is covered by a thin membrane called a conjunctiva

A

cornea

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17
Q

what is right behind the cornea

A

the anterior chamber

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18
Q

___ is the clear fluid secreted by the _____

A

aqueous humor, ciliary body

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19
Q

where does the aqueous humor drain

A

canal of schlemm at the cornea scleral junction

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20
Q

what is a similarity between the anterior and posterior chamber

A

they are both filled with aqueous humor

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21
Q

the sclera is made of
a) connective tissue
b) elastic tissue
c) fibrous tissue

A

a

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22
Q

true or false the crystalline lens gets more elastic as we age

A

false - gets less elastic as we get older

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23
Q

what is immediately behind the anterior chamber

A

crystalline lens

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24
Q

explain the vitreous chamber

A

it is right behind the crystalline lens and filled with a gelatinous fluid called vitreous humor; it is under a lot of pressure

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25
Q

what part of the eye contains several layers of cells and where is it located

A

back of the eye is the retina

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26
Q

rods and cones are
a) processing cells
b) receptor cells

A

b

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27
Q

what are the three types of processing cells

A

bipolar, ganglion and amacrine

28
Q

how are the retinal visual cells nourished

A

by retinal pigment epithelium outside the neurosensory retina

29
Q

how are the outer layers of retina nourished

A

by the choroid which provides oxygen and nourishment

30
Q

what is the pathway of light

A

strikes cornea -> passes through anterior chamber -> pupil -> focuses on lens -> passes through the vitreous chamber -> strikes retina -> light absorbed by receptor cells -> any excess light not absorbed will be absorbed by the pigment cells to prevent reflection

31
Q

what part of the eye is most affected by accommodation

A

the anterior curvature of the lens

32
Q

suspensory ligaments are also called ____

A

zonule fibers

33
Q

define refraction

A

deflection undergone by a light ray passing from one medium to another in which the velocity is different

34
Q

____ is the distance from the cornea to the point where parallel light rays converge

A

focal distance

35
Q

1/focal distance =

A

diopters

36
Q

name the three refractive errors

A

myopia, hyperopia and presbyopia

37
Q

myopia causes
a) nearsightedness because of a too long eye
b) far sightedness because of a too short eye
c) nearsightedness because of a too short eye
d) far sightedness because of a too long eye

A

a

38
Q

what are the two parts of the eye that are the most important in properly focusing light entering the eyes

A

cornea and lens

39
Q

explain this prescription
-1.00, -1.25 X 180

A

-1.00 indicates the prescription corrects for nearsightedness
-1.25 is the lens power for correction of astigmatism
X 180 is the axis of lens power

40
Q

what are the first layer of cells that the light strikes
a) ganglion cells
b) receptor cells

A

a

41
Q

list the functions of retinal pigment epithelium

A
  1. absorbs the light not absorbed by the photoreceptors
  2. transports nutrients/ions to photoreceptors
  3. helps regenerate 11-cis-retinal
42
Q

true or false - photoreceptors undergo renewal

A

true - daily

43
Q

choose if this is a feature of cones or rods

100-125 million per retina

A

rods

44
Q

choose if this is a feature of cones or rods

low sensitivity

A

cones

45
Q

choose if this is a feature of cones or rods

day vision

A

cones

46
Q

choose if this is a feature of cones or rods

more numerous in the retinal periphery

A

rods

47
Q

choose if this is a feature of cones or rods

lots of convergence

A

rods

48
Q

choose if this is a feature of cones or rods

vision in shades of grey

A

rods

49
Q

choose if this is a feature of cones or rods

concentrated in fovea

A

cones

50
Q

choose if this is a feature of cones or rods

6 million per retina

A

cones

51
Q

choose if this is a feature of cones or rods

high acuity pathway

A

cones

52
Q

list the steps of visual transduction in the DARK

A

DARK -> high concentration of cyclic GMP -> triggers depolarization -> initiates the opening of calcium channels in the synaptic terminal -> photoreceptors will release of glutamate -> inhibition of bipolar cells -> no longer any AP in ganglion cell and lateral geniculate nucleus

53
Q

list the steps of visual transduction in the light

A

LIGHT -> isomerization of retinal -> G protein. transducin is activated -> activates phosphodiesterase -> breakdown of cGMP -> sodium channels close -> hyperpolarization -> calcium channels close -> prevents release of inhibitory transmitter -> excitation of bipolar cells -> AP in ganglion cell and lateral geniculate nucleus

54
Q

what vitamin is retinal derived from

A

vitamin A

55
Q

what are the differences between OFF and ON bipolar cells

A

OFF events - photoreceptor is depolarized -> light hyperpolarizes photoreceptor cells -> inhibition of glutamate release -> reduced excitation by glutamate receptors -> hyperpolarization of bipolar cells -> less neurotransmitter -> hyperpolarization of ganglion cells -> less AP

ON cells - photoreceptor is depolarized -> light hyperpolarizes photoreceptor cells -> inhibition of glutamate release -> reduced inhibition -> depolarization of bipolar cells -> more neurotransmitter -> depolarization of ganglion cells -> more AP

56
Q

all trans retinal is reduced to ____

A

trans retinol

57
Q

how is pigment reformed

A

trans retinal is reduced to trans retinol -> exits cell -> transported to retinal pigment epithelium -> converted to 11-cis-retinal -> returns to rod -> combined with opsin

58
Q

_____ is the only cell whose output goes to the brain

A

ganglion cells

59
Q

stimulation of what causes a change in the output of bipolar/ganglion cells

A

receptive field

60
Q

true or false - receptive fields do not overlap

A

false - they do

61
Q

where are the axon terminals of the ON channels

A

inner plexiform layer

62
Q

what do OFF bipolar cells express

A

AMPA and kainate type receptors

63
Q

AMPA and kainate type receptors are anion/cation channels

A

cation

64
Q

what do ON bipolar cells express

A

mGluR6, a metobotropic receptor

65
Q

what happens when the metobortropic receptor binds to glutamate

A

closing of the cation channel TRPM1

66
Q

true or false - all optic fibers cross at the optic chiasma

A

false - not all

PHYSL 200 (17 decks)

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