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PHYSL 212 > VISION > Flashcards

VISION Flashcards

1
Q

how are mecahno receptors activated

A

mechanical deformation in nerve endings

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2
Q

how are thermo receptors activated

A

temp

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3
Q

how are chemo receptors activated

A

chemicals in enviro

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4
Q

what energy is required to activate photo receptors

A

photon energy

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5
Q

what do osmo receptors regulate

A

osmolarity of body fluids

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6
Q

what are AP s of nociceptors interpreted as

A

pain

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7
Q

what receptors are involved in hearing

A

meachno receptors

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8
Q

what mechanical deformation occurs in mechano receptors for hearing

A

bending of hair

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9
Q

what receptors are involved in vision

A

photo receptors

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10
Q

what is sensory perception

A

converting en from outside of body into form that body can interpret

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11
Q

what form of en can body interpret

A

AP s

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12
Q

what is adequate stimulus

A

particular type of energy that sensory ending responds to

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13
Q

what must all energy be converted to

A
  • electrochemical energy (AP s)

- change in mem potential

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14
Q

what is primary transduction process

A

conversion of one form of energy / event to electrochemical energy

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15
Q

what is primary transduction process for vision

A

photons of light converted to AP

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16
Q

what is primary transduction process for hearing

A
  1. sound waves in air get converted to sound waves in fluid
  2. sound waves in fluid cause bending of hair
  3. bending of hair opens channels
  4. opening of channels changes mem potential
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17
Q

what is generator potential

A

stimulus that causes depolarization or hyper polarization in sensory nerve

graded

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18
Q

when is generator potential hyper polarizing

A

if K + leaves cell

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19
Q

what is generator potential proportional to

A

strength of stimulus

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20
Q

what determines how many stimuli can be discriminated

A
  1. range

2. stimuli

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21
Q

VISION what does range of visual system depend on

A

the wavelengths visible to humans

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22
Q

VISION what is sclera

A

white fibrous part of eye

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23
Q

VISION what is cornea

A

clear continuation of sclera

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24
Q

VISION what is conjunctiva

A

thin protecting mem covering cornea

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25
Q

VISION what is most powerful part of light focusing system

A

cornea

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26
Q

VISION where does light get partially focused

A

cornea

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27
Q

VISION what is anterior chamber

A

small chamber behind cornea

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28
Q

VISION what is anterior chamber filled with

A

aqueous humor

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29
Q

VISION what secretes aqueous humor

A

ciliary body

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30
Q

VISION what drains aqueous humor

A

canal of schlemm

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31
Q

VISION where is canal of schlemm

A

where cornea and sclera join

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32
Q

VISION what is posterior chamber

A

chamber behind anterior chamber

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33
Q

VISION what is posterior chamber filled with

A

aqueous humor

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34
Q

VISION where is crystalline lens located

A

behind anterior chamber

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35
Q

VISION what are characteristics of lens

A
  1. convex

2. elastic

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36
Q

VISION what does fluid filled anterior chamber allow cornea and lens to do

A

act as single optical unit

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37
Q

VISION what is cornea analogous to

A

coarse adjustment

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38
Q

VISION what is lens analogous to

A

fine adjustment

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39
Q

VISION where is vitreous chamber located

A

behind lens

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40
Q

VISION what is vitreous chamber filled with

A

vitreous humor

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41
Q

VISION what is the function of vitreous humor

A

maintain shape of eye

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42
Q

VISION what does fibrous tissue and fluid in eye allow

A

deformation without breaking

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43
Q

VISION where is retina located

A

back of eye

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44
Q

VISION what kind of layers of cells does retina contain

A
  1. receptor cells

2. processing cells

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45
Q

VISION where is choroid layer located

A

behind retina

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46
Q

VISION what is choroid layer composed of

A

layer of pigment cells

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47
Q

VISION what do pigment cells contain

A

melanin

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48
Q

VISION what does melanin absorb

A

light not absorbed by receptor cells to prevent light scatter

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49
Q

VISION what would light scatter result in

A

blurred image

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50
Q

VISION what is accommodation

A

process by which curvature of lens increased

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51
Q

VISION when does accommodation occur

A

during near vision

52
Q

VISION what holds lens in place behind iris

A

suspensory ligaments

53
Q

VISION what are suspensory ligaments attached to

A

ciliary muscles

54
Q

VISION what are ciliary muscles

A

sphincter like muscles

55
Q

VISION what happens when ciliary muscle relaxes

A
  1. tension on suspensory ligaments increases
  2. lens flattens
    - distance vision (unaccomodated)
56
Q

VISION what happens when ciliary muscle contracts

A
  1. tension on suspensory ligaments decreases
  2. lens roundens
    - near vision (accomodated)
57
Q

VISION what is refraction

A

deflection of light from straight path when passing from one medium to another

58
Q

VISION what is focal distance

A

distance from refractive surface to point where parallel light rays converge

59
Q

VISION what is refractive surface

A

cornea

60
Q

VISION what is refractive power

A

reciprocal of focal distance

61
Q

VISION what is unit for refractive power

A

diopter

62
Q

VISION what is refractive power of cornea

A

42 dioptewrs

63
Q

VISION what does refractive power of cornea mean

A

parallel light striking surface of cornea will be focused 2.4 cm behind it

64
Q

VISION what is 2.4 cm behind cornea

A

retina

65
Q

REFRACTIVE ERRORS what is myopia

A

nearsightedness

66
Q

REFRACTIVE ERRORS what causes myopia

A

eyeball too long

67
Q

REFRACTIVE ERRORS what is hyperopia

A

farsightedness

68
Q

REFRACTIVE ERRORS what is cause of hyperopia

A

eyeball too short

69
Q

REFRACTIVE ERRORS in myopia where is image focused

A

in front of retina

70
Q

REFRACTIVE ERRORS in hyperopia where is image focused

A

behind retina

71
Q

REFRACTIVE ERRORS how is myopia corrected

A
  • concave / neg lens

- moves focal point back

72
Q

REFRACTIVE ERRORS how is hyperopia corrected

A
  • convex / pos lens

- moves focal point forward

73
Q

REFRACTIVE ERRORS what is presbyopia

A

lens stiffening

74
Q

REFRACTIVE ERRORS what causes presbyopia

A

age

75
Q

REFRACTIVE ERRORS what does presbyopia result in

A

decreased ability to focus for close up vision

76
Q

REFRACTIVE ERRORS why is there decreased ability to focus

A
  • lens loses flexibility

- lens loses ability to accomodate

77
Q

REFRACTIVE ERRORS what is astigmatism

A

when cornea or lens is more curved in one plane than another

78
Q

REFRACTIVE ERRORS what are cornea and lens both involved in

A

focusing light to retina

79
Q

REFRACTIVE ERRORS what is result of astigmatism

A

eye unable to focus light rays to single point causing vision to be out of focus

80
Q

REFRACTIVE ERRORS what is correction for astigmatism

A

cylindrical lens

81
Q

REFRACTIVE ERRORS how is cylindrical lens diff from spherical lens

A

focus light into a line instead of a point

82
Q

REFRACTIVE ERRORS what does uneven curvature result in

A
  1. difference in refraction

2. point of light seen as line or oval

83
Q

REFRACTIVE ERRORS what is emmetropia

A

normal vision

84
Q

what is fovea

A

area of greatest visual acuity

85
Q

what is fovea lacking

A

blood vessels

86
Q

RETINA why does retina appear to be built upside down

A
  • first layer of cells light strikes is ganglion cells

- second layer light strikes is receptor cells

87
Q

RETINA what are ganglion cells a part of

A

final common pathway

88
Q

RETINA how are axons of ganglion cells diff from other cells in retina

A

able to conduct AP

89
Q

RETINA what happens despite retinal being transparent

A
  • some light absorbed

- some light reflected away

90
Q

RETINA what is pathway of light once it reaches retina

A
  1. ganglion cells (processing)
  2. bipolar cells (processing)
  3. receptor cells
    - rods
    - cones
  4. choroid layer
91
Q

RETINA what does outer segment of photoreceptors contain

A

discs

92
Q

RETINA what do discs contain

A

visual pigment rhodopsin

93
Q

RETINA what happens to discs

A
  1. shed
  2. phagocytized by retinal pigment epithelium
  3. replaced (from bottom to top)
94
Q

RETINA what are 2 types of receptor cells

A
  1. rods

2. cones

95
Q

RETINA which of receptor cells is more numerous

A

rods

96
Q

RETINA what is vision w rods

A

shades of grey

97
Q

RETINA what is sensitivity of rods

A
  • high ==> require lower light

- night vision

98
Q

RETINA what kind of acuity pathways do rods have

A

low acuity (not a lot of sharp detail)

99
Q

RETINA what happens to pathways that serve rods

A
  • converge

- multiple rods feeding into fewer bipolar cells

100
Q

RETINA what is vision w cones

A

colour

101
Q

RETINA what is sensitivity of cones

A
  • low ==> require brighter light

- day vision

102
Q

RETINA what kind of acuity pathways (cones)

A

high acuity (a lot of sharp detail)

103
Q

RETINA what happens to pathways that serve cones

A
  • little convergence
104
Q

RETINA what does little convergence result in

A

no loss of acuity

105
Q

RETINA where are cones concentrated

A

in fovea

106
Q

DARK in the dark what do receptor cells have a high conc of

A

cyclic GMP

107
Q

DARK what does high conc of cGMP allow

A
  • Na channels open
  • Na flow into cell
  • mem depol
108
Q

DARK what does mem depol result in

A
  1. Ca channels open
  2. Cell increases release of inhibitory glutamate
  3. inhibitory glutamate inhibits bipolar cells
109
Q

DARK what does inhibition of bipolar cells result in

A
  • no AP conducted to ganglion cells
  • no AP conducted to optic nerve
  • no AP conducted to lateral geniculate nucleus of thalamus
110
Q

STEPS IN PHOTO RECEPTION what are steps in photo reception

A
  1. light strikes 11-cis retinal
  2. 11-cis retinal converted to all trans retinal
  3. conformational changes in opsin leads to production of metarhodopsin 2
  4. metarhodopsin 2 activates transducin G protein
  5. transducin activates phosphodiesterase
  6. phosphodiesterase catalyzes conversion of c GMP to 5’-GMP
    (cGMP levels decrease)
  7. Na channels close
  8. hyper polarization decreases release of inhibitory glutamate
111
Q

what are 2 types of glutamate receptors on bipolar cells

A
  1. ionotropic (depolarization)

2. metabotropic (hyper polarizing)

112
Q

what does decreased release of glutamate result in for ionotropic receptors

A
  • no depol
  • hyper polarization
  • inhibit bipolar cells
113
Q

what does decreased release of glutamate result in metabotropic receptors

A
  • no hyper polarization
  • depolarization
  • excite bipolar cells
114
Q

LIGHT in light what do receptor cells have low concentration of

A

cyclic GMP

115
Q

LIGHT what does low concentration fo cGMP allow

A
  • Na channels close
  • no Na flow into cell
  • mem hyper polarization
116
Q

LIGHT what does hyper polarization result in

A
  1. Ca channels close
  2. decrease release of inhibitory glutamate
  3. bipolar cells not inhibited
117
Q

LIGHT what does lack of inhibition of bipolar cells result in

A
  • AP in ganglion cell
  • AP in optic nerve
  • AP in lateral geniculate nucleus of thalamus
118
Q

what surrounds receptor cells

A

retinal pigment of epithelium

119
Q

what is the function of RPE

A
  1. absorb light that does not get absorbed by photoreceptors
  2. transport nutrients and ions to photoreceptors
  3. required for regeneration of 11-cis retinal
  4. required for shedding of photoreceptor disks
120
Q

how is trans retinal converted back to 11 cis retinal

A
  1. trans retinal reduced to trans retinol
  2. trans retinol exits rod and goes to RPE
  3. trans retinol converted to 11 cis retinol
  4. 11 cis retinol converted to 11 cis retinal
  5. 11 cis retinal returns to rod
  6. 11 cis retinal combines w opsin to form rhodopsin pigment
121
Q

RECEPTIVE FIELD what is receptive field

A

area on retina which when stimulated enhances / inhibits activity of bipolar or ganglion cells

122
Q

RECEPTIVE FIELD how are receptor fields set up

A
  1. RF s have areas that excite ganglion cell when stimulated
  2. RF s have areas that inhibit ganglion cell when stimulated
123
Q

what is pathway of axons from ganglion closest to nose

A
  1. ganglion cell to optic nerve
  2. optic nerve to optic chiasm
  3. cross over to opposite side
124
Q

what is pathway of axons from ganglion closest to temporal lobe

A
  1. ganglion cell to optic nerve
  2. optic nerve to optic chiasm
  3. do not cross over to opposite side
125
Q

where does info about L visual field go

A

R side of brain

126
Q

where does info about R visual field go

A

L side of brain

PHYSL 212 (22 decks)

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