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S2 Neuroscience > Visual System > Flashcards

Visual System Flashcards

1
Q

optic disk

  • produces
  • exit of…
A

produced blind spot

exit of optic nerve

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2
Q

macula lutea

-contains

A

central fovea (pit)

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3
Q

components of retina

A

optic disc

macula lutea

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4
Q

cell layers of retina

A

pigment cell layer
layer of rods and cones
ganglion cell layer

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5
Q

retina: pigment cell layer
- derived from
- attaches retina to…
- absorbs…

A

derives from choroid
attaches to eyeball
absorbs stray light

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6
Q

rods

  • location
  • function
A

periphery of retina
function
-low light vision
-perception of movement

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7
Q

cones

-location

A

central retina

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8
Q

what is the name for the structure that contains only cones that is the area of maximum visual acuity, color, and brightness discrimination

A

fovea

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9
Q

retina: ganglion cell layer
- _____ of these cells form the _____
- _____ are described for ganglion cells

A

myelinated axons of these cells form the optic nerve

receptive fields are described for ganglion cells

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10
Q

in the normal eye, a _____ image of the object is focused on the retina

A

inverted

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11
Q

light is refracted by the…

-which parts inverts the image?

A

cornea
aqueous humor
lens (where image is inverted)
vitreous humor

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12
Q

lens

  • function
  • how does this occur?
  • -what is this called
A

changes the refractive power of the eye
accomplished by changing the shape fo the lens
-called accommodation

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13
Q

how does the lens shape change for

  • close viewing
  • distant viewing
A

rounder for close viewing

flatter for distant viewing

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14
Q

accommodation

-to view a near object, the lens must _____ its refractive power by becoming _____

A

increase by becoming more convex (rounder)

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15
Q

at rest, how is the lens held in a relatively flat shape?

A

suspensory fibers that connect it to the ciliary muscle

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16
Q

how does the ciliary muscle react to accommodate for near vision?
-when this happens, what property of the lens allows it to contract into a more spherical shape

A

ciliary muscle contracts, reducing the tension on the suspensory fibers
its natural elasticity

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17
Q

ciliary muscle controlled by what type of nerve fibers

A

parasympathetic nerve fibers

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18
Q

emmetropia

-what is it

A

naturally occurring condition where the image of an object is focused on the retinal surface

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19
Q

what are some refractive abnormalities

A

hypermetropia
myopia
presbyopia

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20
Q

hypermetropia

  • another name
  • what happens
A

far-sightedness

focal point falls behind the retinal surface

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21
Q

myopia

  • another name
  • what happens
A

near-sightedness

falls in front of the retina

22
Q

presbyopia

  • what is it
  • what is a common external accommodation for this?
A

loss of lens elasticity noted with age
corrective prescriptions may then include a part of the lens that corrects vision for distance and a part that corrects for near vision = bifocals

23
Q

rods

  • excitation threshold level
  • used in _____ conditions
  • rod acuity is _____
A

low excitation threshold
used in dim conditions
rod acuity is poor (doesn’t matter, because when light is low, you can’t see small objects anyways)

24
Q

cones

  • excitation threshold level
  • used in _____ conditions
  • acuity is…
A

high excitation level
used in high light conditions
acuity is high

25
Q

which provide color vision: rods or cones

A

cones

26
Q

ability to distinguish color vision is due to presence of…

A

three separate cone populations, each of which is maximally sensitive to a different wavelength of light

27
Q

what are the difference cone populations responsible for color vision?

A

blue
green
red

28
Q

color blindness

-results from…

A

absence of one or more of the cone populations

29
Q

what is the rest of the retina doing that is not responsible for sensing light?

A

neural coding of visual signals

30
Q

generator potentials

  • originate…
  • transmitted to…
  • altered by…
A

originate in receptors
transmitted to bipolar cells
altered by other cells in the retina

31
Q

generator potential pathway can be visualized as…

-what are they?

A

two separate systems

  • vertical system
  • horizontal system
32
Q

how do signals pass in the vertical system?

A

from receptors to bipolar cells to ganglion cells

33
Q

what happens in the horizontal system?

A

horizontal and amacrine cells provide lateral interactions (lateral inhibition) between the different vertical system components

34
Q

ganglion cellc

-function

A

final stage of retinal processing

transmit information to subcortical visual centers in the brain

35
Q

optic nerve is formed by what types of cells

A

axons of ganglion cells

36
Q

receptive field of a ganglion definition

A

area in visual space (or the corresponding area of retinal surface) which, upon illumination, influence the signaling of that neuron
-remember on-center and off-surround

37
Q

ganglion cells can be categorized on the basis of their…

A

response duration

morphology

38
Q

“sustained” ganglion cells

  • characteristic
  • typically correspond with what size ganglion cells
A

respond as long as the stimulus remains within the receptive field
small ganglion cells (P-cells)

39
Q

“transient” ganglion cells

  • characteristic
  • typically correspond with what size ganglion cells
A

respond only when the light is turned on or off

correspond with large ganglion cells (M-cells)

40
Q

M-cells

-primarily concerned with…

A

signaling changes in the scene being viewed

-includes movement, changes in light and dark contrast, and basic form analysis

41
Q

P-cells

-primary function

A

provide information about fine detail (high resolution analysis of image) and color

42
Q

what is a visual field

A

the part of space that is being viewed

43
Q

signals transmitted through the central visual pathways are divided into…

A

primary and secondary pathways

44
Q

explain the concept of hemifields within the visual field

-this is accomplished at the level of the…

A

visual field can be divided by a vertical line at the fixation point into a left and right hemifield
each half of the brain receives information only from the opposite (contralateral) hemifield
this separation is accomplished at the level of the optic chiasm

45
Q

relation bewteen binocularity and homonymity

A

images of the visual world are composed of information from the two eyes (binocular) which are merged to form a single image (homonymity)

46
Q

homonymous

-this term, as it applies to visual fields, describes…

A

both eyes viewing the same or corresponding visual fields

47
Q

which part of the brain is perceiving the contralateral half of the visual field
-what is this called?

A

primary visual cortex

called contralateral homonymous perception

48
Q

everything caudal to the optic chiasm is carrying only…

A

contralateral homonymous sensation

49
Q

hemianopia

  • also called…
  • what is it
A

also called hemianopsia

loss of visual perception of half of the entire visual field

50
Q

heteronymous

-as it applies to visual fields, what does it describe

A

describes individual eye viewing different visual fields

51
Q

if each eye is only able to see the ipsilateral temporal visual field and not the nasal visual fields, the deficit would be classified as

  • give both names
  • which is preferred
A

binasal heteronymous hemianopia

binasal hemianopia is preferred

S2 Neuroscience (25 decks)

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