Special Senses: Vision Flashcards

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1
Q

Optic Nerve (2)

A

sensory for vision

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2
Q

Oculomotor (3)

A

Iris, ciliary body control, all eye muscles except the superior oblique and lateral rectus

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3
Q

Trochlear (4)

A

motor for superior oblique muscle

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4
Q

Abducens (6)

A

motor for lateral rectus muscle

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5
Q

Trigeminal (5)

A

general sensation of eye

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6
Q

Humans are sensitive to visible light. Visible light wavelength is…

A

380nm - 760nm

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7
Q

Conjunctiva

A

thin mucous membrane that covers the inside of the eyelid and the sclera, made of unkeratinized stratified squamous and stratified columnar epithelium with goblet cells

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8
Q

Goblet cells

A

modified epithelial cells that secrete mucous on mucous membranes

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9
Q

Eyelids

A

thin fold of skin that covers and protects the eye

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10
Q

Eye muscles

A

levator palpebrae superioris, superior rectus, inferior rectus, medial rectus, lateral rectus(6), inferior oblique muscle, superior oblique muscle(4)

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11
Q

Cornea

A

transparent front part of the eye that covers the pupil, iris, and anterior chamber, refracts light

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12
Q

Sclera

A

opaque, fibrous, protective outer layer of the human eye, made from collagen and elastic fiber

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13
Q

Iris

A

thin, annular structure responsible for controlling the diameter and size of the pupil, controls the amount of light reaching the retina

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14
Q

Pupil

A

hole located in the center of the iris that allows light to strike the retina, appears black because light rays entering the pupil are absorbed

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15
Q

Choroid

A

thin, pigmented, vascular layer, between the sclera and retina, brings oxygen and nutrients to the outer retina

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16
Q

Ciliary Body

A

part of the eye that included the ciliary muscle and the ciliary epithelium

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17
Q

Ciliary muscle

A

controls the shape of the lens

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18
Q

Ciliary epithelium

A

produces aqueous humor

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19
Q

Lens

A

transparent biconvex structure that refracts light, focusing it on the retina

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20
Q

Accommodation Triad (Near)

A
  1. Ciliary Body Contracts (relaxed suspensory ligaments, lens balls up)
  2. Eyes converge
  3. Pupil constricts
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21
Q

Accommodation Triad (Far)

A

ciliary body relaxes, contracted suspensory ligaments, flat lens

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22
Q

Retina

A

innermost layer of light sensitive tissue, images are processed here then nerve impulses are sent to the brain

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23
Q

Optic Nerve

A

cranial nerve 2, sensory for vision, sight sensation

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24
Q

Anterior chamber of the eye

A

aqueous humor filler space inside the eye between the iris and the cornea

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25
Q

Interior chamber of the eye

A

located between the iris and lens, important for aqueous humor circulation

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26
Q

Aqueous humor

A

transparent fluid similar to plasma, fills the anterior and posterior chambers of the eye, maintains pressure, provides nutrients, and prevents dryness

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27
Q

Canal of Schlemm

A

Drains aqueous humor from the eye to the veins

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28
Q

Vitreous humor

A

clear gel that fills the space between the lens and retina, keeps eye round and clear, allows light to pass through, can protect the retina from shock

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29
Q

Blood supply to the Retina

A

Choroid and Retinal Blood Vessels

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30
Q

Ganglion layer

A

made of retinal ganglion cells and displaced amacrine cells
final output neurons of the retina that receives information from the photoreceptors
axons of retinal ganglion cells form the optic nerve fibers

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31
Q

Amacrine cells

A

inhibitory neurons
detect directional motion

32
Q

Bipolar Cells

A

neurons located in the retina, transmits signals from the photoreceptors to the ganglion cells

33
Q

Rods

A

photoreceptor cells in the retina, vision good with black and white and contrast

34
Q

Cones

A

photoreceptor cells in the retina, vision good with color

35
Q

Pigmented epithelium of Choroid

A

supplies blood and nutrients to retinal visual cells

36
Q

Fovea or Macula Lutea

A

cone concentration, high acuity vision,

37
Q

Optic disk

A

blind spot, beginning of optic nerve

38
Q

Myopia (near sighted)

A

eye is too long, concave lens correction

39
Q

Hyperopia (far sighted)

A

eye is too short, convex lens correction,

40
Q

Presbyopia (aging)

A

cross-linked lens wont change shape, loss of close vision

41
Q

Astigmatism

A

uneven thickness of cornea

42
Q

Detached Retina

A

retina at the back of the eye pulls away from its normal position, will result in the retina losing blood and nutrient supply

43
Q

Cataract

A

cloudy lens, gradual

44
Q

Glaucoma

A

excess intraocular pressure

45
Q

Medial retinas

A

peripheral vision

46
Q

Lateral retinas

A

central vision

47
Q

Optic Nerve

A

conducts axons from each eye

48
Q

Optic Chiasm

A

axons from the medial retina cross over

49
Q

Optic Tract

A

axons from medial and lateral lessions affect both right or left visual field

50
Q

Lateral Geniculate Body

A

located at the end of the optic tract, receives visual information, processes and relays visual information to the primary visual cortex

51
Q

Optic Radiations to Occipital Lobe (OROL)

A

aka. geniculocalcarine tract, connects lateral geniculate body to occipital lobe

52
Q

OROL lateral

A

top portion of right or left visual field

53
Q

OROL medial

A

bottom portion of right or left visual field

54
Q

Macular Sparing

A

lesions at the end of path do not affect macula, which has already diverged

55
Q

Ocular Dominance Columns

A

alternating right and left eye information projects to cortex

56
Q

Photopigments

A

aka. Rhodopsins, unstable pigments that undergo a chemical change when they absorb light, synthesized from Vitamin A

57
Q

Rhodopsin

A

chromatophore, retinal (from Vit A), opsin (protein)

58
Q

Opsin

A

protein which forms part of Rhodopsin, released by the action of light

59
Q

In the Dark the cells…

A

Rods have open Na+ channels (cGMP)
cell is hypopolarized -40mv (dark current)
tonic release of glutamate (inhibitory) on bipolar cells

60
Q

In the Light the cells…

A
  1. Light contracts photocell discs (Rod)
  2. Rhodopsin conformational change (11cis->11trans+opsin)
  3. Free opsin activates transducin
  4. transducin activates phosphodiesterase
  5. phosphodiesterase deactivartes cGMP to 5’GMP
  6. Closes Na+ channels
  7. Na+/K+ ATPase pump dominates
  8. Cell Hyperpolarizes -70mv
  9. decrease in the release of glutamate nuerotransmitter on bipolar cells
  10. release of inhibition of bipolar cells
  11. Bipolar cells depolarize
  12. Action potentials are produced
  13. Ganglion cells send signals to the optic nerve
61
Q

In the Light the cells… (2)

A

Activates Bipolar cell Action Potential
Activates Ganglion cell Action Potential

62
Q

Light Adaptation

A

Light bleaches available photopigment (retinal + opsin), sensitivity to light is reduced

63
Q

Dark Adaptation

A

Dark pushes reaction to generate more sensitive rhodopsins, (dark adapted)

64
Q

Color Vision

A

cones, each cone cell is sensitive to specific wavelengths (Trichromatic Vision)

65
Q

Blue cone

A

440nm (blue hv)

66
Q

Green cone

A

535nm (green hv)

67
Q

Red cone

A

565nm (yellow hv), humans weakly responsive to red spectrum

68
Q

Retina Reaction to light

A
  1. Photoreceptor Cell
  2. Bipolar cell with horizontal interaction
  3. Ganglion cell
69
Q

Center/Surround Concept

A

horizontal cells are inhibitory to surrounding photoreceptor cells that determine image representation on ganglion cells,
On Center / Off surround
Off Center / On surround

70
Q

Ganglion cells

A

W cells
X cells
Y cells

71
Q

W cells

A

smallest ganglion cells, rod information, esp movement

72
Q

X cells

A

most common ganglion cells, cone(color) information

73
Q

Y cells

A

largest ganglion cells, least common ganglion cells, rapid movement, changes in intensity

74
Q

Eye/Head movements coordinated through the Superior Colliculus

A

Saccade Movement
Pursuit Movement

75
Q

Saccade Movement

A

successive fixation points, reading, watching telephone poles while in a car

76
Q

Pursuit Movement

A

eyes remained fixed on moving object and will track it, not voluntary, eyes must track a moving object, eyes will Saccade if it is voluntary

77
Q

Pathway for light entering the retina

A
  1. Ganglion cells
  2. Bipolar cells
  3. Photoreceptor cells
  4. Choroid layer