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Neuroscience 2016 > Chapter 9: The Eye > Flashcards

Chapter 9: The Eye Flashcards

1
Q

Fovea

A

densely packed cones
cones have three types of opsin (red, green blue) –> color vision
one cone –> one bipolar –> one ganglion cell
area of highest acuity

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2
Q

Peripheral retina

A

more rods than cones
rods: more photopigment=rhodopsin, more sensitive to light
convergence of rods to ganglion cells
greater sensitivity but lower acuity

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3
Q

Light transduction: G protein coupled neurotransmitter receptor

A

Stimulus: transmitter
Receptor activation: change in protein conformation
G protein response: Binds to GTP
Second messenger change: INCREASE second messenger
Ion channel response: increase or decrease conductance

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4
Q

Light transduction: photopigment

A

Stimulus: Light
Receptor activation: change in protein conformation
G protein response: binds GTP
Second messenger change: DECREASE second messenger
Ion channel response: DECREASE Na+ conductance

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5
Q

Transduction of light by rods

A
  1. Light activates (bleaches) rhodopsin
  2. Transducin, the G-Protein, is stimulated
  3. Phosphodiesterase (PDE), the effector enzyme, is activated
  4. PDE Activity reduces the cGMP level
  5. Na+ channels close, cell membraine hyperpolarizes
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6
Q

look at page 306: laminar organization of the retina

A

Ganglion cell layer, inner plexiform layer, inner nuclear layer, outer plexiform layer, outer nuclear layer, layer of photoreceptor outer segments, pigmented epithelium

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7
Q

Path of light

A

Photoreceptors, bipolar cells, ganglion cells

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8
Q

Generic receptive field

A

the part of the sensory surface that, when stimulated, causes a neuronal response

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9
Q

Visual receptive field

A

the area of the retina that, when stimulated, causes a neuronal response in visual pathway

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10
Q

OFF bipolar cells

A

hyperpolarized when light is shined onto a cone

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11
Q

OFF bipolar cells

A

hyperpolarized when light is shined onto a cone
have ionotropic glutamate receptors: hyperpolarization means one less neurotransmitter released means more hyperpolarization

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12
Q

ON bipolar cells

A

depolarized when light is shined onto cone

g-protein-coupled (metabotropic) receptors

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13
Q

Receptive field surround

A

surrounding area of retina, input via horizontal ceclls

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14
Q

Receptive field surround

A

surrounding area of retina, input via horizontal cells

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15
Q

on center ganglion cell pathway

A 
center of cone
glutamate (transmitter)
mGluR6 (receptor)
On center bipolar cell depolarized
Glutamate
AMPA, kainate, NMDA
on center ganglion cell
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16
Q

off center ganglion cell pathway

A

cone
AMPA kainate (receptor)
off center bipolar cell hyperpolarized
off center ganglion cell

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17
Q

off center ganglion cell pathway

A

cone
AMPA kainate (receptor)
off center bipolar cell hyperpolarized
off center ganglion cell

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18
Q

Mtype ganglion cells

A

5%

movement

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19
Q

Ptype ganglion cells

A

90%

more detailed form

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20
Q

Every sensory system has:

A
  1. primary area in cortex
  2. relay nucleus in thalamus
  3. surface where transduction occurs
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21
Q

Frequency of light

A

number of waves per second

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22
Q

amplitude

A

difference between wave trough and peak

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23
Q

Visible light higher vs lower energy

A

higher energy is blues

lower is reds

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24
Q

reflection

A

bouncing of rays off of surface (page 296)

depends on angle at which light ray strikes surface

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25
absorption
transfer of light energy to a particle or surface
26
refraction
forms images in eye | the bending of light rays that travel from one transparent medium to another
27
Pupil
opening of eye, allows light to enter and reach retina
28
iris
contains two muscles to make it larger and smaller when it contracts
29
cornea
glassy transparent external surface of eye, is continuous with sclera
30
sclera
the white of the eye forms tough wall of eyebrow has three extraocular muscles that move eyeball in orbit
31
eye's orbit
eye socket in skull
32
conjunctiva
membrane that folds back from inside of eyelids and attaches to sclera
33
optic nerve
carries axons from retina, exits from back of eye, passes through orbit, and reaches base of brain near pituitary gland
34
optic disk
where optic nerve fibers exit retina | blind spot because there are no photoreceptors
35
blind spots
optic disk, where large blood vessels exit because they cast shadows on retina
36
macula
central vision, part of the retina, high quality of central vision because there are no blood vessels
37
fovea
dark spot; retina thinnest here; center of retina
38
aqueous humor
watery fluid that nourishes cornea; between cornea and lens
39
lens
transparent; located behind iris
40
ciliary muscle
forms ring inside eye, attachment site of ligaments
41
vitreous humor
more viscous jelly-like fluid, in between lens and retina, keeps eyeball spherical
42
focal distance
distance from refractive surface to the point where parallel light rays converge depends on curvature of cornea tighter curve=shorter focal distance
43
accommodation
refractive power bringing rays into focus on retina by changing shape of lens ciliary muscle contracts and swells in size (inside ring smaller and decreasing tension, lens becomes rounder and thicker, increases curvature of lens, increasing refractive power)
44
strabismus
eye disorder: imbalance in extraocular muscles of two eyes, eyes point in opp directions
45
cataract
eye disorder: clouding over of lens
46
glaucoma
progressive loss of vission assocsiated with intra ocuar pressure, pressure in aqueous humor
47
glaucoma
progressive loss of vision associated with intra ocular pressure, pressure in aqueous humor
48
retinitis pigmentosa
progressive degeneration of photoreceptors, loss of peripheral and night vision, tunnel vision
49
macular degeneration
losing central vision
50
visual acuity
the ability of the eye to distinguish between two points near each other
51
visual angle
measurement by distance across retina in terms of degrees
52
most direct pathway for visual information
photoreceptors to bipolar cells to ganglion cells
53
laminar organization
cells are organized in layers
54
ganglion cell layer
innermost retinal layer; cell bodies of ganglion cells
55
inner nuclear layer
contains cell bodies of bipolar cells, horizontal cells, amacrine cells
56
outer nuclear layer
cell bodies of photoreceptors
57
inner plexiform layer
contains synaptic contacts between bipolar amacrine ganglion cells
58
outer plexiform layer
photoreceptors make synaptic contact with bipolar and horizontal cells
59
layer of photoreceptor outer segments
light sensitive elements of retina; embedded in pigmented epithelium
60
photopigments
light sensitive disk membranes absorb light in the outer segment
61
rod photoreceptors
long, cylindrical outer segment with many disks | way more rods than cones
62
cone photoreceptors
shorter, tapering outer segment with fewer membranous disks | color
63
duplex retina
how rods and cones are two complementary systems in one eye
64
scotopic conditions
nighttime lighting | rods
65
photopic conditions
daytime lighting cones therefore much greater spacial sensitivity on central retina
66
mesopic conditions
intermediate light levels (indoor lighting, outdoor traffic lighting at night) both rods and cones
67
rods or cones in the fovea?
most cones in fovea; no rods in fovea
68
photoreceptors
convert/transduce light energy hyperpolarize in response to light light reduces cGMP, Na+ channels close, more negative, hyperpolarization
69
rhodopsin
photopigment in rods; bleaching, which stimulates G protein transucin, etc rods more sensitive to light because cascade for transduction-->amplification
70
young-helmholtz trichromacy theory
theory of color vision | red green and blue light make white, all colors seen through these three

Neuroscience 2016 (7 decks)

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