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Organ systems > Eye structures > Flashcards

Eye structures Flashcards

1
Q

Where does object procession happen?

A

In the ventral “what” stream. This passes through the temporal lobe

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2
Q

Where does spatial processing happen?

A

In the dorsal “where” stream through the parietal lobe.

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3
Q

Where to both the spacail and object processing stream come from and go to?

A

Both come from occipital lobe that recieves visual input and they take their individual streams to the frontal lobe.

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4
Q

What do sensory receptors sample?

A

small amounts of energy from the environment

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5
Q

How does CNS do with sensory info?

A

processes and forms an internal representation of external and internal world.

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6
Q

Why would CNS use feedback to regulate receptors and sensory activity at all levels?

A

To maintain a tolerable range of sensory stimulation

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7
Q

Three coats of eyeball

A

fibrous coat, vascular coat, nervous coat

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8
Q

What parts make up fibrous coat of eye?

A

Sclera, dense white CT and Cornea which is transparent

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9
Q

What part of epithelium reduces spread of infection?

A

Bowmans basment membrane

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10
Q

What makes up outerlayer of cornea?

A

stratified squamous epi

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11
Q

what is the corneal stroma?

A

Below the epithelium, it has fibroblast that make lamellae of collagen fibers

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12
Q

what is the basement membrane of corenal epithelium called?

A

descemets membrane

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13
Q

what is on the inner surface of cornea?

A

Simple squamous endothelium that transfers nutrients from aqueous humor to cornea

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14
Q

Where do corneal epithelial cells come from?

A

adjacent corneosclera limbus

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15
Q

how is the DNA in the cornea protected from UV?

A

nuclear ferritin

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16
Q

what the corneal epithelia stem cells called?

A

transient amplifying cells, TAC

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17
Q

What holds lense in place?

A

suspensory ligaments

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18
Q

what are the fibers called that attach and hold lense in place?

A

Zonule fibers

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19
Q

Where do zonule fibers extend from?

A

ciliary body

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20
Q

What maintains the resting convexity of lense?

A

outward pull of suspensory ligaments from ciliary body when muscle is relaxed with intrinsic elastic fibers

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21
Q

What do intrinsic elastic fibers of lens cause?

A

inherent tendency to bulge or increase the convexity of lense

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22
Q

what is the outer capsule of lenes made of?

A

elastic collagen IV and glycoproteins

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23
Q

what produces new lens cells?

A

germinal zone around outer edge of lens

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24
Q

what happens to new lens cells as they migrate away from germinal zone?

A

they lose their nuclei so that they are transparent

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25
Q

presbyopia

A

far sightedness, can see clearly far away

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26
Q

what causes presbyopia

A

loss of elasticity in lense, not weak eye muscles

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27
Q

what is implicated in cataracts?

A

oxidative damage may be causeing lense to become obaque

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28
Q

what type of vision does lense need to be the most convex?

A

for close up vision

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29
Q

What is it called when ciliary muscle changes convexity of lens?

A

accomidation

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30
Q

How does ciliary muscle relax tension on suspensory ligaments?

A

By contracting they relax ligaments enabeling close up vision

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31
Q

does close or far light diverge more?

A

nearby light diverges more and requires greater refraction to hit the right spot on retina

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32
Q

what determines ultimately where the lense focuses light?

A

the length of the eyeball,

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33
Q

long eyeball causes what?

A

Myopia, near sightedness, retina

34
Q

short eyeball causes what?

A

Hyperopia, far sightedness

35
Q

Where is light focused in hyperopia?

A

light is focused beyond retina

36
Q

Where is light focused in myopia

A

light is focused before retina

37
Q

Where is aqueous humor located?

A

anterior and posterior chamber

38
Q

What absorbs humor into venous system?

A

schlemms canal , ouside edge of cornea

39
Q

What can cause glaucoma?

A

poor schlemms canal drainage or over production of humor

40
Q

What can block flow out of schlemms canal?

A

adherence of iris to lense that blocks flow

41
Q

What structures does iris contain?

A

pigmented striations of CT, blood vessels and smooth muscle

42
Q

What is the stroma of the iris?

A

CT with melanocytes

43
Q

What type of muscles does iris have? 2

A

constrictor and dilator pupillae

44
Q

Where is pigment epithelium located in iris

A

continuous on posterior surface of iris, it doesn’t allow any light in.

45
Q

what light gets scattered more red or blue?

A

Blue gets scattered more (atmosphere, eye bits)

46
Q

what determines color of eye if all pigment is brown?

A

the pattern of light refraction by melanin

47
Q

What causes blue eyes?

A

Deep pigment scattered by the stromal layer refraction of blue light

48
Q

Why is melanin brown?

A

it absorbs blue grean and reflects black yellow and red

49
Q

What system controls the sphincter pupillae?

A

parasympathetic - it constricts pupil

50
Q

What system controls the dialator pupillae?

A

syspathetic, opens pupil to allow more light

51
Q

what does pupil size determine in addition to regulating light intensity?

A

determines focal range,

52
Q

What does smaller pupil do to range of focus?

A

small pupil increases range of focul

53
Q

Where does the parasympathetic neurons to eye travel from?

A

CN III the ocular motor nerve

54
Q

Where is the ciliary ganglion for eye?

A

near posterior surface of eyeball

55
Q

Where does sympathetic nerves for eye come from?

A

superior cervical ganglion that has postganglionic neeurons that project axons along arteries to iris

56
Q

what does parasympathetics do to eye?

A

constrict pupil and contract lense

57
Q

where are the preganglionic neurons located for parasympathetics to eye?

A

Edinger whestphal nucleus

58
Q

What do the post ganglionic neurons in the ciliary ganglion activate? 2

A

sphincter pupillae and ciliary muscle to contract lense (relax fibers)

59
Q

What is the purpose of the pupillary light reflex?

A

maintain homeostatic levels of light entering eye

60
Q

what cells in retina respond to ambient light?

A

melanopsin ganglion cells

61
Q

what do the melanopsin ganglion cells activate?

A

pretectum and edinger Westphal nuclei in brain

62
Q

What coordinates both eyes?

A

Pretectal nucleus of midbrain

63
Q

What does the pupillary light reflex look like?

A

reflexive constriction of both pupils in response to light shone in eyes.

64
Q

path of pupillary light relfex?

A

light, melanopsin ganglion cells, pretectal n. EW nucleus, ciliary ganglion, pupil constricion

65
Q

Preganglionic neurons from where innervate superior cervical ganglion cells

A

Preganglionic neurons are from T1 and T2

66
Q

What two things do the postganglionic neurons activate?

A

Dilatory pupillae and tarsal muscle to raise eyelid

67
Q

the postganglionic neurons that innervate superior cervical ganglion are from what system?

A

sympathetic

68
Q

What type of reflexes control iris and upper eyelid?

A

local sympathetic reflexes with influence from limbic system

69
Q

when would limbic system and hypothalamus influence local reflexes of iris?

A

during emotional state.

70
Q

what is the function of the tarsal muscle

A

to raise eyelid in emotional states - sympathetic

71
Q

what would damage to part of sympathetic NS cause to happen to eye area

A

drooping eyelid, horners syndrome.

72
Q

what causes floaters?

A

age related, collagen fiber bundles that cast shadows

73
Q

what is vitreous body made of>

A

hyauronic acid and type II collagen, 99% water

74
Q

what is the eyeball derived from?

A

the embryonic brain

75
Q

what forms lens placode?

A

ectoderm from the neural tube, not neural tissue

76
Q

What are the neural and pigmented layers of retina derived from?

A

optic vesicle

77
Q

neural layer

A

neruons and photoreceptors

78
Q

pigment layer

A

retinal pigment epithelium RPE

79
Q

What is outer layer of eye derived from?

A

meningeal tissue

80
Q

what nourishes vitreous body and lense in embryo?

A

hyaloid artery

Organ systems (14 decks)

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