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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
Q

absorption

A

transfer of light energy to a particle or surface

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26
Q

refraction

A

forms images in eye

the bending of light rays that travel from one transparent medium to another

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27
Q

Pupil

A

opening of eye, allows light to enter and reach retina

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28
Q

iris

A

contains two muscles to make it larger and smaller when it contracts

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29
Q

cornea

A

glassy transparent external surface of eye, is continuous with sclera

30
Q

sclera

A

the white of the eye
forms tough wall of eyebrow
has three extraocular muscles that move eyeball in orbit

31
Q

eye’s orbit

A

eye socket in skull

32
Q

conjunctiva

A

membrane that folds back from inside of eyelids and attaches to sclera

33
Q

optic nerve

A

carries axons from retina, exits from back of eye, passes through orbit, and reaches base of brain near pituitary gland

34
Q

optic disk

A

where optic nerve fibers exit retina

blind spot because there are no photoreceptors

35
Q

blind spots

A

optic disk, where large blood vessels exit because they cast shadows on retina

36
Q

macula

A

central vision, part of the retina, high quality of central vision because there are no blood vessels

37
Q

fovea

A

dark spot; retina thinnest here; center of retina

38
Q

aqueous humor

A

watery fluid that nourishes cornea; between cornea and lens

39
Q

lens

A

transparent; located behind iris

40
Q

ciliary muscle

A

forms ring inside eye, attachment site of ligaments

41
Q

vitreous humor

A

more viscous jelly-like fluid, in between lens and retina, keeps eyeball spherical

42
Q

focal distance

A

distance from refractive surface to the point where parallel light rays converge
depends on curvature of cornea
tighter curve=shorter focal distance

43
Q

accommodation

A

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
Q

strabismus

A

eye disorder: imbalance in extraocular muscles of two eyes, eyes point in opp directions

45
Q

cataract

A

eye disorder: clouding over of lens

46
Q

glaucoma

A

progressive loss of vission assocsiated with intra ocuar pressure, pressure in aqueous humor

47
Q

glaucoma

A

progressive loss of vision associated with intra ocular pressure, pressure in aqueous humor

48
Q

retinitis pigmentosa

A

progressive degeneration of photoreceptors, loss of peripheral and night vision, tunnel vision

49
Q

macular degeneration

A

losing central vision

50
Q

visual acuity

A

the ability of the eye to distinguish between two points near each other

51
Q

visual angle

A

measurement by distance across retina in terms of degrees

52
Q

most direct pathway for visual information

A

photoreceptors to bipolar cells to ganglion cells

53
Q

laminar organization

A

cells are organized in layers

54
Q

ganglion cell layer

A

innermost retinal layer; cell bodies of ganglion cells

55
Q

inner nuclear layer

A

contains cell bodies of bipolar cells, horizontal cells, amacrine cells

56
Q

outer nuclear layer

A

cell bodies of photoreceptors

57
Q

inner plexiform layer

A

contains synaptic contacts between
bipolar
amacrine
ganglion cells

58
Q

outer plexiform layer

A

photoreceptors make synaptic contact with bipolar and horizontal cells

59
Q

layer of photoreceptor outer segments

A

light sensitive elements of retina; embedded in pigmented epithelium

60
Q

photopigments

A

light sensitive disk membranes absorb light in the outer segment

61
Q

rod photoreceptors

A

long, cylindrical outer segment with many disks

way more rods than cones

62
Q

cone photoreceptors

A

shorter, tapering outer segment with fewer membranous disks

color

63
Q

duplex retina

A

how rods and cones are two complementary systems in one eye

64
Q

scotopic conditions

A

nighttime lighting

rods

65
Q

photopic conditions

A

daytime lighting
cones
therefore much greater spacial sensitivity on central retina

66
Q

mesopic conditions

A

intermediate light levels (indoor lighting, outdoor traffic lighting at night)
both rods and cones

67
Q

rods or cones in the fovea?

A

most cones in fovea; no rods in fovea

68
Q

photoreceptors

A

convert/transduce light energy
hyperpolarize in response to light
light reduces cGMP, Na+ channels close, more negative, hyperpolarization

69
Q

rhodopsin

A

photopigment in rods; bleaching, which stimulates G protein transucin, etc
rods more sensitive to light because cascade for transduction–>amplification

70
Q

young-helmholtz trichromacy theory

A

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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