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A & P II > Eye Anatomy & Physiology > Flashcards

Eye Anatomy & Physiology Flashcards

1
Q

where is the eyeball located?

A

in orbits on either side of the nasal cavity

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2
Q

what provides protective cushioning and keeps the eyeball in proper position?

A

adipose tissue

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3
Q

what’s another word for eyelids?

A

palpebrae

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4
Q

what are the eyelids job?

A

to prevent access by foreign objects and distribute tears during blinking

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5
Q

what are the 3 parts of the eyelid?

A

tarsal plates, tarsal glands, and lacrimal caruncle

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6
Q

what are tarsal plates?

A

thin pieces of dense regular collagenous connective tissue

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7
Q

what are the tarsal plates job?

A

to reinforce each eyelid

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8
Q

what are tarsal glands?

A

modified sebaceous glands located with tarsal plates

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9
Q

what is the tarsal glands job?

A

to secrete oil that prevents eyelids from sticking together

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10
Q

what is the lacrimal caruncle?

A

fleshy structure at medial commissure

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11
Q

what is the lacrimal caruncles job?

A

secretes whitish lubricating substance

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12
Q

eyebrow’s purpose?

A

to prevent perspiration from running into the eyes; reduce glare from bright light; important for facial expressions

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13
Q

eyelash’s purpose?

A

associated with sensitive nerve endings so causes blinking when objects touch them; reduces eye injury

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14
Q

what is the conjunctiva?

A

thin continuous epithelial membrane; translucent membrane in which tiny blood vessels can be seen

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15
Q

what are the 2 layers of the conjunctiva?

A

palpebral and ocular conjunctiva

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16
Q

palpebral conjunctiva purpose?

A

covers eyelid inner surface

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17
Q

ocular conjunctiva purpose?

A

covers anterior white part of eyeball

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18
Q

job of the lacrimal apparatus?

A

produces and drains tears from eye

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19
Q

where is the lacrimal gland?

A

in superolateral region of orbit

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20
Q

job of the lacrimal gland?

A

releases tears and mucus into tiny ducts; lubricates and washes away debris

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21
Q

what is the passageway of tears?

A

lacrimal gland – lacrimal punctum – lacrimal sac – nasolacrimal duct

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22
Q

what is the lacrimal puncta?

A

tiny openings in medial edge of each eyelid

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23
Q

where is the lacrimal sac?

A

located in small depression in lacrimal bone

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24
Q

what are the extrinsic eye muscles?

A

superior, inferior, lateral, medial rectus, superior oblique, inferior oblique, CN IV (trochlear), CN VI (abducens), and CN III (oculomotor)

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25
Q

purpose of superior oblique?

A

contraction depresses eye and moves it laterally

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26
Q

purpose of inferior oblique?

A

contraction elevates and moves eye laterally

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27
Q

what is Strabismus?

A

aka lazy eye; disorder present at birth; eyeballs are not properly aligned with one another

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28
Q

what are the 3 tissue layers of the eyeball?

A

fibrous, vascular, and neural

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29
Q

what does the fibrous layer consist of?

A

connective tissue; sclera and cornea

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30
Q

what does the vascular layer consist of?

A

blood vessels; iris, ciliary body, and choroid

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31
Q

what does the neural layer consist of?

A

photoreceptors; retina

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32
Q

what is the fibrous layer?

A

outermost layer

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33
Q

what is the sclera?

A

white part of the eye; covers nearly the entire eye; irregularly arranged collagen fibers

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34
Q

purpose of the sclera?

A

resists deformation from external or internal forces to maintain shape

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35
Q

what is the cornea?

A

continuous with sclera anteriorly; translucent instead of opaque due to parallel arrangement of collagen fibers

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36
Q

purpose of the cornea?

A

avascular (no blood vessels); allows light to pass into the eyeball

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37
Q

what is the vascular layer?

A

middle layer; absorbs excess light

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38
Q

what is the choroid?

A

coat; contains capillaries and pigment

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39
Q

purpose of the choroid?

A

minimizes scattering of incoming light rays

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40
Q

purpose of the ciliary body?

A

contains ring of smooth muscle that surrounds lens

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41
Q

what are suspensory ligaments?

A

connect ciliary body to lens

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42
Q

purpose of suspensory ligaments?

A

allows for contraction and relaxation; changes shape of lens to focus light

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43
Q

what is the iris?

A

colored region of anterior eye

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44
Q

what is the pupil?

A

opening in center of iris through which light enters the eyeball

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45
Q

where is the pupillary sphincter and pupillary dilator muscles?

A

in iris

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46
Q

purpose of pupillary sphincter muscle?

A

CONTRACTS TO MAKE PUPIL SMALLER (increased light intensity); contracts during parasympathetic stimulation; reduces size of pupil; restricts amount of light entering eyeball

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47
Q

purpose of pupillary dilator muscle?

A

CONTRACTS TO MAKE PUPIL LARGER (decreased light intensity); contracts during sympathetic activation; allows pupil to increase in size; more light enters eyeball

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48
Q

what is the neural layer?

A

innermost layer of eyeball; incomplete layer; only deep to choroid coat

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49
Q

what are the 2 portions of the neural layer?

A

superficial and deep layers

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50
Q

what is the superficial layer?

A

consists of thin, pigmented epithelium

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51
Q

purpose of the superficial layer?

A

reduces light scattering and nourishes photoreceptors

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52
Q

what is the deep layer?

A

consists of photoreceptor cells and cells that form optic nerve

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53
Q

purpose of photoreceptor cells?

A

detect and transduce light stimuli into electrical signals

54
Q

what are the photoreceptors in the neural layer called?

A

rods and cones

55
Q

what do rods allow us to see?

A

black and white vision in low light levels and peripheral vision

56
Q

what do cones allow us to see?

A

high-acuity color vision in higher light levels

57
Q

what is the ora serrata?

A

visible boundary between anterior edge of retina and posterior edge of ciliary body

58
Q

what is the macula lutea?

A

contains large number of photoreceptors

59
Q

what is the fovea centralis?

A

central region of macula lutea; contains large number of cones tightly packed together

60
Q

purpose of the fovea centralis?

A

allows for detailed vision and ability to focus on object

61
Q

what is macular degeneration?

A

leads to progressive loss of visual acuity; particularly of visual field; may also cause visual distortion and changes in color perception

62
Q

what is the optic disc?

A

aka blind spot; does not contain photoreceptors or capture visual images

63
Q

what are the lens?

A

slightly flattened sphere behind pupil and iris; contains cells (lens fibers) that lack nuclei; tightly packed; translucent; connected to ciliary body by suspensory ligaments

64
Q

purpose of lens?

A

focuses light on retina from objects near eye

65
Q

the eyeball is divided by?

A

the lens and ciliary body

66
Q

what are the cavities of the eye?

A

posterior and anterior

67
Q

what is the posterior cavity?

A

larger cavity BEHIND lens; contains vitreous humor

68
Q

what is vitreous humor?

A

made mostly of collagen and water

69
Q

purpose of vitreous humor?

A

presses retina against choroid; helps maintain eyeball shape

70
Q

what is the anterior cavity?

A

in FRONT of lens and ciliary body; contains posterior & anterior chambers and scleral venous sinus

71
Q

where is the posterior chamber?

A

between lens and iris

72
Q

where is the anterior chamber?

A

between iris and cornea

73
Q

what is aqueous humor?

A

watery fluid secreted by ciliary body; flows from posterior chamber through pupil into anterior chamber

74
Q

what is the scleral venous sinus?

A

aka canal of Schlemm; blood vessel network at anterior edge of iris

75
Q

purpose of the scleral venous sinus?

A

drains aqueous humor out of anterior chamber

76
Q

what is vision?

A

perception of light reflected by various objects; determine object’s size, shape, and color; interpret object distance, rate, and direction of movement

77
Q

what is electromagnetic radiation?

A

energy traveling in range of wavelengths (nanometers)

78
Q

what is visible light?

A

range of wavelengths that human eye can detect as range of particular colors

79
Q

blue and violet =

A

shorter wavelengths

80
Q

red =

A

longer wavelengths

81
Q

what is a photon?

A

basic unit of light energy; stimulates photoreceptors in retina

82
Q

what is refractive index?

A

amount of refraction

83
Q

air refractive index =

A

1; density similar to air so light does not refract

84
Q

water refractive index =

A

greater than 1; density greater than air so light refracts

85
Q

greater angle =

A

greater refraction

86
Q

what are the convex lens?

A

surface that bulges outward in middle region

87
Q

purpose of convex lens?

A

causes light rays to bend inward or converge as they pass through

88
Q

what are concave lens?

A

thicker on edge and depressed in middle region

89
Q

purpose of concave lens?

A

causes light rays to diverge or spread out (unfocused)
**rays converging on focal point are said to be focused

90
Q

light rays focus on which part of the eye for clear vision?

A

retina

91
Q

when light hits the lens, what happens?

A

fine tuning and adjustment; change shape

92
Q

when light hits the cornea, what happens?

A

refractive index close to water

93
Q

what is emmetropic state?

A

eye is relaxed and focusing on distant objects; lens is in normal flattened shape; parallel light rays are minimally refracted by cornea and focused on retina; tension on suspensory ligaments

94
Q

what is accommodation?

A

objects closer to the eye need more refraction; lens become more thickened; suspensory ligaments slacken

95
Q

ability to focus on near objects also needs

A

pupillary constriction and convergence

96
Q

what is pupillary constriction?

A

limits amount of scattered light that makes objects appear blurry; enters edge of lens; objects appear more focused

97
Q

what is convergence?

A

process by which eyeballs move more medially to direct light rays on to photoreceptor-dense region of fovea

98
Q

what are the errors of refraction?

A

accommodation affected due to aging lens or shape of eyeball; hyperopia, myopia, and astigmatism

99
Q

what is near point of accommodation?

A

increases with age

100
Q

what is presbyopia?

A

near point of accommodation is greater than 10-20 inches; corrected with reading glasses or bifocals

101
Q

what is hyperopia?

A

farsightedness; eyeball is too short or cornea is too flat; focuses behind retina; causes blurry vision when looking at close objects

102
Q

what is the correction for hyperopia?

A

convex lenses causing more light to converge on retina; LASIK

103
Q

what is myopia?

A

nearsightedness; distance between cornea and lens is too great or cornea is too curved; light is focused in front of retina, blurring objects viewed at a distance

104
Q

what is the correction for myopia?

A

concave lenses diverge incoming light before it contacts lens; LASIK

105
Q

what is astigmatism?

A

curvature of lens or cornea is irregular; light rays are not evenly refracted; blurred vision at all distances

106
Q

what are the corrections for astigmatism?

A

corrective lenses that adjust for specific abnormal corneal or lens curvature; LASIK

107
Q

what does the retina’s structure inner layer consist of?

A

photoreceptors; rods and cones

108
Q

function of cones?

A

function best in bright light for processing high-resolution color vision

109
Q

function of rods?

A

do not detect colors; most sensitive in low light and as component of peripheral vision

110
Q

what does the retina’s structure outer layer consist of?

A

vitreous humor; bipolar, retinal ganglion, and horizontal and amacrine cells

111
Q

what are bipolar cells?

A

neurons that communicate with retinal ganglion cells

112
Q

what are retinal ganglion cells?

A

in anterior-most region of retina; axons form optic nerve (CN II)

113
Q

what are horizontal and amacrine cells?

A

involved in image processing

114
Q

what consist of rod structure?

A

cylindrical outer segments, rhodopsin, and retinal

115
Q

what are cylindrical outer segments?

A

contain 100s of flattened discs containing pigment Rhodopsin that absorbs light; do not distinguish between different wavelengths of light

116
Q

what is Rhodopsin?

A

composed of protein opsin and pigment retinal; pigment that absorbs light

117
Q

what is retinal?

A

derived from vitamin A; pigment

118
Q

what consist of cone structure?

A

iodopsin and photopsin

119
Q

what is iodopsin?

A

composed of retinal and protein photopsin

120
Q

what is photopsin?

A

similar to opsin but has slightly altered structure; allows it to absorb diferent wavelengths of light

121
Q

what are the 3 forms of photopsin?

A

blue, green, or red wavelengths

122
Q

characteristics of adaptation to darkness?

A

cones can not function due to light suddenly reduced; rods are slow to degenerate enough rhodopsin to function; retina sensitive to light; up to 40 minutes to be completely functional

123
Q

characteristics of adaptation to light?

A

bleaches rods and cones, blinding glare; rods become nonfunctional (rhodopsin is bleached as fast as it is regenerated); cones can regenerate functional pigments faster, able to respond within few minutes as their sensitivity decreases

124
Q

what is the visual field?

A

what is seen with that eye alone, with both eyes open; field is divided into left and right with focal point in center

125
Q

what is the retina’s role in the visual pathway?

A

detects visual stimuli from portions of right and left visual fields

126
Q

what is stereoscopic vision?

A

depth perception; eyes face anteriorly (binocular); brain compares overlapping images to determine distance an object is from eyes

127
Q

what is depth perception?

A

distance an object is from eyes

128
Q

what is the consensual pupillary response?

A

constriction of both pupils in response to light entering left or right pupil only; reflectively to prevent damage to retina, optic nerve, and brainstem

129
Q

what are the optic tracts?

A

where axons exit the optic chiasma

130
Q

what is the primary visual cortex?

A

occipital lobe

131
Q

what is the optic chiasma?

A

axons carrying visual stimuli cross here; all stimuli from right visual field are processed by left hemisphere and vice versa

A & P II (9 decks)

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