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exci 360 final > visual system > Flashcards

visual system Flashcards

1
Q

the eye is a fluid filled sphere enclosed by what 3 layers of tissue (what is their order from outermost to innermost)

A

sclera (outermost), choroid (intermediate) and retina (innermost)

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2
Q

what are the 2 fluid compartments of the eye

A

aqueous humor and vitreous humor

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3
Q

describe aqueous humor (where, consistency, function)

A

in ant chamber
watery liquid
supplies nutrients to surrounding structures

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4
Q

describe vitreous humor (where, consistency, function)

A

fills space btw back of lens and retina
thick gelatinous substance
maintains shape of eye and supplies nutrients to surrounding structure

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5
Q

what is the sclera

A

white fibrous tissue forming the outermost layer of the eye

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6
Q

what does the sclera become in front of the eye

A

cornea

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7
Q

what is the cornea

A

transparent tissue that separates and protects ere from external environment and allows light rays into the eye

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8
Q

what is the choroid

A

capillary bed that nourishes retinal cells

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9
Q

whats the ciliary body and what two parts does it have to it

A

a ring of tissues that encircles the lens and consists of a muscular (ciliary m.) and vascular part (ciliary processes)

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10
Q

whats the function of the ciliary muscle and what connects it to the lens

A

controls the shape of lens
Zonule fibers

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11
Q

whats the function of ciliary processes

A

produces aqueous humor in ant chamber

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12
Q

whats the iris, what does it contain and whats their function

A

colored portion of the eye seen thru cornea
contains 2 sets of m. that contract and adjust size of pupil

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13
Q

what does the lens do

A

it refracts light rays coming into eye and generates a focused image on the surface of the retina

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14
Q

what does accommodation of the lens mean and what part of the eye does these accommodations

A

dynamic changes in refractive power of the lens to form a shape image on the retina
done by contraction of ciliary m.

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15
Q

what accommodation of the lens is done for distant vision

A

lens becomes thin and flat, less refractive power

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16
Q

what accommodation of the lens is done for near vision

A

lens becomes thick and round, more refraxctive power

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17
Q

where is the image focused in emmetropia

A

right on the retina (normal eye)

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18
Q

describe myopia (how does the lens accommodate, where is the image, hard to see what, corrected by what)

A

lens doesn’t accommodate enough
image is in front of retina
hard to see distant objects
corrected by converging (convex) glasses

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19
Q

describe hyperopia (how does the lens accommodate, where is the image, hard to see what, corrected by what)

A

lens over accommodates
image is focused beyond the retina
hard to see nearby objects
corrected by diverging (concave) glasses

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20
Q

the retina is considered to be part of what

A

the nervous system

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21
Q

what is the retina’s function

A

it contains neurons that are sensitive to light, and convert visual info to electrical signals and transmit it to the brain

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22
Q

what are the 2 photoreceptor neurons

A

rods and cones

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23
Q

describe rods (shape, number, location in retina, luminosity level, vision accuracy, photosensitive pigments, type of cell, color vision)

A

shape: rod-shaped (rectangular head)
number: 120 millions
location in retina: periphery
luminosity level: dim light (highly sensitive to light)-night vision
vision accuracy: low resolution
photosensitive pigments: rhodopsin (found in carrots)
type of cell: 1: monochromic (absorb white color)
color vision: no

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24
Q

describe cones (shape, number, location in retina, luminosity level, vision accuracy, photosensitive pigments, type of cell, color vision)

A

shape: cone-shaped (triangular head)
number: 8 millions
location in retina: center (fovea)
luminosity level: bright light (low sensitivity to light)- day vision
vision accuracy: high resolution
photosensitive pigments: iodopsin, porphyropsin, cyanopsin
type of cell: 3 types; S-cones (blue), M-cones (green), L-cones (red)
color vision: yes

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25
Q

what are the 5 classes of neurons of the retina

A

photosensitive
bipolar cells
ganglion cells
horizontal cells
amacrine cells

26
Q

what forms the optic nerve

A

axons of the ganglion cells

27
Q

what cells regulate the activity of photosensitive neurons

A

horizontal cells

28
Q

what cells are the lateral communication between neurons

A

amacrine cells

29
Q

what is the electrical activity of photosensitive and retinal neurons for dark light

A

dark light –> cone cell depolarized –> bipolar cell hyperpolarized (active inhibition) –> ganglion cell hyperpolarized (passive inhibition) –> no info transmitted to the brain

30
Q

what is the electrical activity of photosensitive and retinal neurons for light light

A

light –> cone cell hyperpolarized –> bipolar cell depolarized –> ganglion cell depolarized –> info transmitted to the brain

31
Q

what are the 2 classes of ganglion cells (what are they active and silent to)

A

on-center cells: active to light spot in center and silent to dark spot in center
off-center cells: silent to light spot in center and active to dark spot in center

32
Q

what other type of cell as on and off-center cells

A

bipolar cells

33
Q

the activity of on-center and off-center ganglion cells are controlled by what and what behavior do these interractions determine

A

multiple interractions btw photosensitive cells, bipolar cells and horizontal cells
center-surround behavior

34
Q

what cells regulate the amount of transmitter that the photosensitive cells release onto bipolar cell dendrites

A

horizontal cells

35
Q

how is an image projected on the retina

A

inverted top to bottom and revered R to L

36
Q

the visual field is divided into what

A

2 hemifields: R and L hemi field

37
Q

the R visual hemi-field is seen by what type of retina

A

right nasal and left temporal retinas

38
Q

the L visual hemi-field is seen by what type of retina

A

left nasal and right temporal retinas

39
Q

what is the name of when visual fields of both eyes overlap in the central portion of visual field

A

binocular visual field

40
Q

what % of optic n. fibers cross at the optic chiasm and what % stay on the same side

A

60% contralateral
40% ipsilateral

41
Q

what retina fibers project to contralateral side

A

fibers fron nasal retina

42
Q

what retina fibers project to ipsilateral side

A

fibers fron temporal retina

43
Q

after the optic hciasm, what do the optic fibers form

A

optic tract

44
Q

where do the majority of the optic fibers terminate

A

Lateral geniculate body in the thalamus

45
Q

what do neurons from the LGB form and where do they terminate

A

optic radiation and they terminate in the striate cortex

46
Q

where do axons of the ganglion cells also project in the midbrain

A

hypothalamus, pretectum, sup colliculus

47
Q

function of hypothalamus

A

reg of circadian rhythm (biological clock)

48
Q

function of pretectum

A

control of pupillary light reflex

49
Q

function of sup colliculus

A

orienting the mvts of head and eyes

50
Q

what are the other names for visual cortex

A

striate cortex, primary visual cortex, V1, Brodmann’s area 17

51
Q

what does the visual cortex process (give examples)

A

basic sensory info sent by retina
examples: place back inverted image to og position, binocular vision, 3D image, …

52
Q

what representation in the visual cortex does the central region (macula, fovea) of the retina have

A

a large representation

53
Q

what is called the 6 cellular layers in the striate cortex

A

cytoarchitecture

54
Q

describe binocular vision (combining inputs from both eyes)

A

-lat geniculate nucleus receives input from both eyes (monocular)
-LGN input remains segregated in layer 4 of the striate cortex (ocular dominance columns) (monocular)
-layer 4 send their outputs to other cortical layers (binocular vision)

55
Q

what is involved in complex visual pathways

A

extrastriate cortex

56
Q

what are the 2 complex visual pathways

A

dorsal (where) path and ventral (what) path

57
Q

what are each pathway responsible for and where do they project to

A

dorsal: project to parietal lobe, and responsible of spatial aspect of vision (analysis of motion)
ventral: projects to temporal lobe responsible for object recognition

58
Q

consequence of damage at Left lat and med visual field before optic chiasm

A

Left is gone R is intact

59
Q

consequence of damage at Left med visual field before optic chiasm

A

R and L lat is intact , L med is gone

60
Q

consequence of damage at L and R visual field at optic chiasm

A

L med and R med are intact, L lat and R lat are gone

61
Q

consequence of damage at visual field at med optic tract before geniculate nucleus

A

L lat and R med are intact, R lat and L med are gone

62
Q

consequence of damage at visual field at med optic tract after geniculate nucleus

A

L lat and R med are intact, R lat and L med are gone

exci 360 final (6 decks)

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