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Special Senses > Vision > Flashcards

Vision Flashcards

1
Q

The act of seeing

A

Vision

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2
Q

More than ________ the sensory receptors in the human body are loacated in the eyes.

A

half

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3
Q

List the accessory structures of the eye

A

eyebrows
eyelashes
eyelids
lacrimal apparatus
extrinsic eye muscles

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4
Q

It protects the eyes from foreign objects, from perspiration and direct rays from the sun.

A

Eyebrows and eyelashes

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5
Q

It shades the eye during sleep. Also, it protect the eyes from excessive light and foreign objects, and spread lubricating secretions over the eyeballs.

A

Upper and lower eyelids (Palpebrae)

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6
Q

The space between the upper and lower eyelids that exposes the eyeball.

A

Palpebral fissure

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7
Q

What are the angles in the palpebral fissure?

A

Lateral commissure
Medial commissure

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8
Q

This angle in the palpebral fissure is narrower and closer to the temporal bone.

A

Lateral commissure

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9
Q

This angle in the palpebral fissure is broader and nearer the nasal bone.

A

Medial commissure

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10
Q

In the medial commissure is a small, reddish elevation, which contains sebaceous (oil) gland and sudoriferous (sweat) glands.

A

Lacrimal caruncle

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11
Q

A thick fold of connective tissue that gives form and support to the eyelids.

A

Tarsal plate

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12
Q

Is a row of elongated modified sebaceous glands that secrete a fluid that helps the eyelid from adhering to each other.

A

Tarsal glands or Meibomian glands

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13
Q

It is a thin, protective mucous membrane composed of nonkeratinized stratified squamous epithelium with numerous goblet cells that is supported by areolar connective tissue.

A

Conjunctiva

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14
Q

Lines the inner aspect of the eyelids.

A

Palpebral conjunctiva

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15
Q

Passes from the eyelids onto the surface of the eyeball, where it covers the sclera but not the cornea.

A

Bulbar conjunctiva

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16
Q

Group of structures that produces and drains lacrimal fluid or tears in a process called lacrimation

A

Lacrimal Apparatus

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17
Q

It is about the shape and size of an almond, secretes lacrimal fluid which drains into 6-12 excretory lacrimal ducts.

A

Lacrimal Gland

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18
Q

These are 2 small openings in each of the papilla of the eyelid at the midline commissure of the eye.

A

Lacrimal Puncta/punctum

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19
Q

These are 2 small ducts connected with to each lacrimal punctum.

A

Lacrimal Canals/ canaliculi
(superior & inferior lacrimal canal)

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20
Q

It is the expanded portion of the nasolacrimal duct.

A

Lacrimal Sac

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20
Q

It is the expanded portion of the nasolacrimal duct.

A

Lacrimal Sac

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21
Q

It carries the lacrimal fluid into the nasal cavity.

A

Nasolacrimal Duct

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22
Q

Flow of Tears

A
  1. LACRIMAL GLAND secretes tears into
  2. LACRIMAL DUCTS, which distribute tears over the surface of eyeball
  3. SUPERIOR OR INFERIOR LACRIMAL CANALICULI drain tears into
  4. LACRIMAL SAC, which drains tears into
  5. NASOLACRIMAL DUCT, which drains tears into
  6. Nasal Cavity
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23
Q

Composition of the lacrimal fluid or tears

A

Salts
Mucus
Lysozyme

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24
Q

What are the functions of the lacrimal fluid

A

Protection
Cleans
Lubricates
Moistens

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25
Q

How much lacrimal fluid is produced per day in each lacrimal gland.

A

1mL

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26
Q

What do you call the bony depressions of the skull wherein the eyes sit?

A

Orbits

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27
Q

Help protect the eyes, stabilize them in three dimensional space, and anchor them to the muscles that produce their essential movements.

A

Orbits

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28
Q

Th extrinsic eye muscles extend from the walls of the bony orbit to the sclera of the eye and are surrounded by a significant quantity of __________________.

A

Periorbital fat

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29
Q

What are the six extrinsic eye muscles?

A

Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique

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30
Q

Extends from the walls of the bony orbit to sclera of the eye.

A

Extrinsic eye muscles

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31
Q

What supplies the six extrinsic eye muscles?

A

oculomotor (III)
trochlear (IV)
or abducens (VI) nerves

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32
Q

Turns the eye upward

A

Superior rectus

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33
Q

Turns the eye downward

A

Inferior rectus

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34
Q

Towards the midline

A

Medial rectus

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35
Q

Towards the lateral side

A

Lateral rectus

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36
Q

These muscles preserve the rotational stability of the eyeball.

A

Oblique muscles

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37
Q

Rotates the eyeball so the cornea turns in a downward and outward direction.

A

Superior Oblique

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38
Q

Rotates the eyeball so the cornea turns in a upward, outward direction.

A

Inferior Oblique

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39
Q

The diameter of eyeball

A

2.5 cm (1 inch)

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40
Q

Of the total surface of the eyeball, how much is exposed?

A

1/6

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41
Q

Bony pyramidal shaped cavity of the skull that holds the eyeball.

A

Orbit

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42
Q

Enumerate the 3 layers/tunics of the eyeball,

A

Fibrous tunic
Vascular tunic/Retina
Nervous tunic

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43
Q

The superficial layer of the eyeball and consists of the anterior cornea and posterior sclera outer later and it is AVASCULAR.

A

Fibrous tunic

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44
Q

It is a transparent coat that covers the colored iris. It is located on the anterior portion and has no capillaries.

A

Cornea

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45
Q

What composes the outer surface of the cornea?

A

Nonkeratinized stratified squamous epithelium

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46
Q

What composes the middle coat of the cornea?

A

collagen fibers and fibroblasts

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47
Q

What composes the inner surface of the inner surface of the cornea?

A

simple squamous epithelium

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48
Q

Permits light to enter the eye (bend/refracts light)

A

Cornea

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49
Q

The “white” of the eye, is a layer of dense connective tissue made up of collagen fibers and fibroblasts.

A

Sclera

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50
Q

Covers the entire eyeball except the cornea.

A

Sclera

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51
Q

It gives shape to the eyeball, makes it more rigid, protects its inner parts and serves as a site of attachment for the extrinsic eye muscles.

A

Sclera

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52
Q

What cranial nerve pierces the posterior portion of sclera?

A

Optic (CN II)

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53
Q

An opening located at the junction of the sclera and cornea. Aqueous humor (a fluid) drains into this sinus.

A

Canal of Schlemm or Scleral Venous Sinus

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54
Q

The middle layer of the eyeball. It contains lots of blood vessels.

A

Vascular tunic/ Uvea

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55
Q

What are the three parts of the vascular tunic?

A

Choroid
Ciliary body
Iris

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56
Q

It is the posterior portion of the vascular tunic, lines most of the internal surface of the sclera.

A

Choroid

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57
Q

Its numerous blood vessels provide nutrients to the posterior surface of the retina.

A

Choroid

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58
Q

What causes the vascular layer to appear dark brown in color?

A

Melanin (produced by melanocytes)

59
Q

Absorbs stray light rays, which prevents reflection and scattering of light within the eyeball.

60
Q

It is the anterior portion of the vascular layer and it is the thickest portion of the vascular tunic which extends from the ora serrata or the retina to the point behind the the junction of the sclera and cornea

A

Ciliary body

61
Q

Protrusions or folds on the internal surface of the ciliary body. They contain blood capillaries that secrete aqueous humor.

A

Ciliary process

62
Q

Extending from the ciliary process are _________________ or suspensory ligaments that attach to the lens.

A

Zonular fibers

63
Q

The jagged anterior margin of the retina.

A

Ora serrata

64
Q

Is a circular band of smooth muscle.

A

Ciliary muscle

65
Q

Lens is relatively flat

A

Distant vision

66
Q

Lens bulges/increases in curvature

A

Near vision

67
Q

The hole in the center of the iris

68
Q

Heavily pigmented back of the eye

A

Choroid and retina

69
Q

When an object is brought closer than __ ft to the eyes, the ciliary muscles contract as a result of parasympathetic stimulation, pulling the ciliary body towards the lens.

70
Q

This reduces tension on the suspensory ligaments of the lens, allowing the lens to assume a more spherical form.

A

Near vision

71
Q

It is flexible, biconvex, transparent disc (crystal clear).

72
Q

Composition of the lens

A

65% water
35% CHON

73
Q

Within the cells of the lens are proteins called___________, arranged like the layers of an onion, make up the refractive media of the lens, which normally is perfectly transparent and lacks blood vessels.

A

Crystallins

74
Q

Helps focus images on the retina to facilitate clear vision.

75
Q

Principal refractive medium (fine-tunes light rays onto the retina to facilitate clear vision)

76
Q

What divides the interior of the eyeball into two cavities?

77
Q

What are the two cavities of the interior of the eyeball?

A

Anterior cavity
Posterior cavity

78
Q

The space anterior to the lens

A

Anterior cavity

79
Q

2 chambers of the anterior cavity

A

Anterior chamber
Posterior chamber

80
Q

Lies between cornea and iris

A

Anterior chamber

81
Q

Lies behind the iris and in front of the zonular fibers and lens

A

Posterior chamber

82
Q

The anterior cavity is filled with ______________________.

A

Aqueous Humor

83
Q

A clear, watery fluid with similar composition as the CSF.

A

Aqueous Humor

84
Q

The larger posterior cavity of the eyeball.

A

Vitreous chamber

85
Q

Composed of 99% water, it is transparent, jelly-like substance. Also contains phagocytic cells that remove debris, keeping the post cavity clear

A

Vitreous Humor

86
Q

4 major functions of vitreous humor

A

a. Contributes partly to the maintenance of IOP
b. Helps prevent the eyeball from collapsing
c. holds the retina in place
d. Helps refract light

87
Q

Is a narrow channel that runs thru the vitreous body from the optic disc to the posterior aspect of the lens.
*in the fetus, this was occupied by the hyaloids artery.

A

Hyaloid Canal

88
Q

The colored portion of the eyeball, is shaped like a flattened donut. It is suspended between the cornea and the lens and is attached at its outer margin to the ciliary process.

89
Q

It consists of melanocytes and circular and radial smooth muscle fibers. The amount of melanin in this part determines the eye color.

90
Q

It regulates the amount of light entering the eyeball through the pupil.

91
Q

The hole in the center of the iris.

92
Q

What are the two types of muscles of the iris?

A

-Circular muscle or sphincter pupillae
-Radial muscles or dilator pupillae

93
Q

The innermost layer of the eyeball

A

Nervous tunic/Retina

94
Q

The inner coat of the eyeball, lines the posterior three-quarters of the eyeball and is the beginning of the visual pathway.

95
Q

It contains the photoreceptor

96
Q

The only structure in the body where blood vessels can be visualized thru and ophthalmoscope.

97
Q

The only structure in the body where blood vessels can be visualized thru and ophthalmoscope.

98
Q

The site where the optic (II) nerve exits the eyeball.

A

Optic disc

99
Q

What bundles with the optic nerve?

A

Central retinal artery
Central retinal vein

100
Q

Fan out to nourish the anterior surface of the retina.

A

Central retinal artery

101
Q

Drains blood from the retina through the optic disc.

A

Central retinal vein

102
Q

What are the layers of the retina?

A

Pigmented layer
Neural layer

103
Q

The non-visual portion. It is a sheet of melanin-containing epithelial cells located between the choroid and the neural part of the retina.

A

Pigmented layer

104
Q

Absorbs stray light rays thus preventing reflection and scattering of light within the eyeball, allowing sharp and clear image.

105
Q

It is a multilayered outgrowth of the brain that processes visual data extensively before sending nerve impulses into axons that form the optic nerve.

A

Neural layer/Sensory retina

106
Q

Three distinct layers of the retinal neurons

A

Photoreceptor layer
Bipolar cell layer
Ganglion cell layer

107
Q

Are specialized cells in the photoreceptor layer that begin in the process by which light rays are ultimately converted to nerve impulses.

A

Photoreceptors

108
Q

Two types of photoreceptors

A

Rods and cones

109
Q

Allow us to see in dim light, such as moonlight. They are very sensitive to light (have low threshold), and does not provide color vision.

110
Q

How many rods does each retina have?

A

120 million rods

111
Q

How many cones does each retina have?

A

6 million cones

112
Q

It is most abundant toward the edge of the retina, thus providing PERIPHERAL VISION.

113
Q

It is made up of CHON (SCOTOPSIN) and a pigment (RETINAL)

114
Q

It is responsible for color vision and function best in bright light.

115
Q

The loss of cones produces _____________________

A

Legal blindness

116
Q

Three types of cones present in the retina

A

Blue cones
Green cones
Red cones

117
Q

Inability to distinguish between certain colors because of the absence or deficiency of 1 or 3 photopigment.

A

Color blindness

118
Q

Inability to see well at dim light

A

Night blindness/Nyctalopia

119
Q

Good vision depends on adequate intake of _______________ -rich vegetables such as: carrots, spinach, broccoli, yellow squash, food that contain vitamin A like liver.

A

Carotenoid

120
Q

Is a small yellow spot near the center of the posterior portion of the retina.

A

Macula Lutea

121
Q

A small/pit depression at the center of the macula lutea. It contains only CONES, thus, the area of highest visual acuity or resolution.

A

Central Fovea (Fovea centralis)

122
Q

Ability to see images clearly

A

Visual Acuity

123
Q

Sharpness of vision

A

Resolution

124
Q

It is the blind spot. It is a white spot just medial to the macula lutea. Where blood vessels, optic nerve enter the eyes. It contains no photoreceptors, thus objects focused on this area cannot be seen.

A

Optic disc

125
Q

A process by which the lens of the eye changes in shape/curvature to adjust for vision at various distances; the lense increases/decrease in its curvature.

A

Accommodation

126
Q

The four media of refraction

A

Cornea
Aqueous humor
Lens
Vitreous humor

127
Q

How many percent of the total refraction of light occurs at the cornea?

128
Q

It is the crossing point of light rays

A

Focal point

129
Q

The process of causing light to converge (bend toward each other)

130
Q

Characteristics of images focused on the retina

A
  1. Inverted/upside-down
  2. They undergo right to left reversal
131
Q

Viewing an object:
The light rays refelcted from the object are nearly parallel to one another

A

At 20 ft. distance

132
Q

Viewing an object:
Light rays that are reflected from the object are divergent (they move away from each other)

A

Near object (Near vision)

133
Q

3 requirements for Accommodation

A
  1. Change in the shape of the lens
  2. Constriction/dilation of the pupils
  3. Convergence of the eyes
134
Q

The minimum distance from the eye that an object can be clearly focused with maximum effort.

A

Near Point of Vision

135
Q

Nearsightedness. Image is focused in front of the retina, thus the person has to move closer to the object to allow clearer vision.

136
Q

Causes for Myopia

A

Elongated eyeball and thickened lens

137
Q

Farsightedness. When the lens is thin, there is lesser refraction/convergence of light rays, thus the image is focused at the back of the retina. Thus, individuals who have this tend to move farther to allow better vision.

A

Hyperopia/Hypermetropia

138
Q

Farsightedness. When the lens is thin, there is lesser refraction/convergence of light rays, thus the image is focused at the back of the retina. Thus, individuals who have this tend to move farther to allow better vision.

A

Hyperopia/Hypermetropia

139
Q

The cornea’s curvature is assymetrical, so light rays are focused at 2 points on the retina, rather than one point.

A

Astigmatism

140
Q

Inflammation of the conjunctiva, usually from bacterial infection.

A

Conjunctivitis

141
Q

Contagious conjunctivitis

142
Q

A cyst caused by infection of the sebaceous glands along the edge of the eyelids.

143
Q

Infection of an eyelash/hair follicle

144
Q

Decrease in the ability of the eye to accommodate for near vision; comes with aging.

A

Presbyopia

145
Q

A defect in which the cornea or lens is not uniformly curved and the image is not sharply focused.

A

Astigmatism

146
Q

Most common cause of blindness

Special Senses (4 decks)

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