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Special Senses > Lesson 2: Structures Involved in Vision > Flashcards

Lesson 2: Structures Involved in Vision Flashcards

1
Q

the act of seeing, is extremely important to human survival. More than half the sensory receptors in the human body are located in the eyes, and a large part of the cerebral cortex is devoted to processing visual information.

A

Vision

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2
Q

Accessory Structures of the Eye:

A

Eyelids
Eyelashes
Eyebrows
Lacrimal Apparatus
Extrinsic Eye Muscles

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3
Q

These structures are not involved directly on visual functions but are primarily designed for:

A

Protection
Lubrication
Movement of the Eyes

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4
Q

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

A

Eyebrows & Eyelashes

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5
Q

It shades the eyes 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
  • special levator muscle in the superior region of the upper eyelid.
A

Levator Palpebrae Superioris Muscle

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7
Q

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

A

Palpebral Fissure

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8
Q

The angle of the palpebral fissure which is broader and nearer to the nasal bone.

A

Medial Commissure

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8
Q

The angle of the palpebral fissure which is narrower and closer to the temporal bone.

A

Lateral Commissure

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9
Q

It is the small, reddish elevation, which contains sebaceous (oil) glands and sudoriferous (sweat) glands.

A

Lacrimal Caruncle

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10
Q

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

A

Tarsal Plate

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11
Q

is a row of elongated modified sebaceous glands that secrete a fluid that helps keep the eyelids from adhering to each other.

A

Tarsal Glands or Meibomian Glands

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12
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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13
Q

lines the inner aspect of the eyelids

A

Palpebral Conjunctiva

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14
Q

passes from the eyelids onto the surface of the eyeball, where it covers the sclera (the “white” of the eye) but not the cornea.

A

Bulbar Conjunctiva

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15
Q

is a group of structures that produces and drains lacrimal fluid or tears in a process called lacrimation.

A

Lacrimal Apparatus

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16
Q

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

A

Lacrimal Gland

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17
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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18
Q

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

A

Lacrimal Canals/ Canaliculi

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19
Q

It is the expanded portion of the nasolacrimal duct.

A

Lacrimal Sac

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20
Q

It carries the lacrimal fluid into the nasal cavity.

A

Nasolacrimal Duct

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21
Q

A composition of lacrimal fluid, described as a protective bactericidal enzyme.

A

Lysozyme

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22
Q

Each gland produces about _______ of lacrimal fluid per day.

A

1 mL

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23
Q

The eyes sit in the bony depressions of the skull called the ______.

A

Orbits

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24
Q

extend from the walls of the bony orbit to the sclera of the eye and are surrounded in the orbit by a significant quantity of periorbital fat. These muscles are capable of moving the eye in almost any direction.

A

Extrinsic Eye Muscles

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25
Q

Six extrinsic eye muscles move each eye:

A

Superior Rectus
Inferior Rectus
Medial Rectus
Lateral Rectus
Superior Oblique
Inferior Oblique

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26
Q

turns the eye upward

A

SR

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27
Q

turns the eye downward

A

IR

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28
Q

turns the eye towards the midline

A

MR

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29
Q

turns the eye towards the lateral side

A

LR

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30
Q

these preserves rotational stability of the eyeball

A

2 Oblique Muscles

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31
Q

rotates the eyeball so the cornea turns in a downward & outward direction.

A

SO

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32
Q

rotates the eyeball so the cornea turns in an upward, outward direction.

A

IO

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33
Q

They are spherical in shape. It measures about 2.5 cm (1 inch) in diameter.

A

Eyeball or Bulbus Oculi

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34
Q

The total surface area of the eyeball, only the ___________ is exposed & the remaining portion is protected by the ORBIT.

A

Anterior 1/6

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35
Q

3 LAYERS/TUNICS OF THE EYEBALL:

A

Fibrous Tunic
Vascular Tunic
Nervous Tunic

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36
Q

is the superficial layer of the eyeball and consists of the anterior cornea and posterior sclera outer layer. It is AVASCULAR.

A

Fibrous Tunic

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37
Q

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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38
Q

Because it is curved, the __________helps focus light onto the retina.

A

Cornea

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39
Q

consists of nonkeratinized stratified squamous epithelium.

A

Outer Surface of the Cornea

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40
Q

consists of collagen fibers and fibroblasts

A

Middle Coat of the Cornea

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41
Q

is simple squamous epithelium

A

Inner Surface of the Cornea

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42
Q

as one of the media for refraction, it permits light to enter the eye (bends/refracts light)

A

Cornea

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43
Q

is the “white” of the eye, is a layer of dense connective tissue made up mostly of collagen fibers and fibroblasts. It is located on the posterior portion.

A

Sclera

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44
Q

The _________covers the entire eyeball except the cornea.

A

Sclera

45
Q

a) it gives shape to the eyeball;
b) makes it more rigid;
c) protects its inner parts;
d) serves as a site of attachment for the extrinsic eye muscles.

A

Sclera

46
Q

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

A

Canal of Schlemm or Schleral Venous Sinus

47
Q

is the middle layer of the eyeball. It contains lots of blood vessels (the layer containing most of the blood vessel of the eyes). It is composed of three parts: choroid, ciliary body, and iris.

A

Vascular Tunic

48
Q

the posterior portion of the vascular tunic, lines most of the internal surface of the sclera. Its numerous blood vessels provide nutrients to the posterior surface of the retina.

A

Choroid

49
Q

_____________ in the choroid absorbs stray light rays, which prevents reflection and scattering of light within the eyeball.

A

Melanin

50
Q

is the anterior portion of the vascular layer. It is the thickest portion of the vascular tunic which extends from the ORA SERRATA of the retina to the point behind the junction of the sclera & cornea.

A

Ciliary Body

51
Q

the jagged anterior margin of the retina

A

Ora Serrata

52
Q

Parts of the Ciliary Body:

A

Ciliary Process
Ciliary Muscle

53
Q

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

A

Ciliary Process

54
Q

Extending from the ciliary process are _________________________ that attach to the lens.

A

Zonular Fibers or Suspensory Ligaments

55
Q

is a circular band of smooth muscle. Contraction or relaxation of the ciliary muscle changes the tightness of the zonular fibers, which alters the shape of the lens, adapting it for near or far vision.

A

Ciliary Muscle

56
Q

lens is relatively flat

A

Distant Vision

57
Q

lens bulges/increases in its curvature

A

Near Vision

58
Q

It is flexible, biconvex, transparent disc (crystal-clear). It is located just posterior to the pupil and iris.

A

Lens

59
Q

The lens is made up of _________ & _________.

A

65% water & 35% CHON

60
Q

Within the cells of the lens are proteins called ___________, arranged like the layers of an onion

A

Crystallins

61
Q

The ________helps focus images on the retina to facilitate clear vision.

A

Lens

62
Q

PRINCIPAL REFRACTIVE MEDIUM (fine-tunes light rays onto the retina to facilitate clear vision)

A

The Lens

63
Q

the space anterior to the lens

A

Anterior Cavity

64
Q

lies between cornea & iris

A

Anterior Chamber

65
Q

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

A

Posterior Chamber

66
Q

what fluid fills the anterior cavity?

A

Aqueous Humor

67
Q

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

A

Aqueous Humor

68
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

69
Q

a narrow channel that runs thru the vitreous body from the optic disc to the posterior aspect of the lens.

A

Hyaloid Canal

70
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 processes.

A

Iris

71
Q

The amount of ___________in the iris determines the eye color.

A

Melanin

72
Q

The eyes appear __________ when the iris contains a large amount of melanin.

A

brown to black

73
Q

The eyes appear __________ when its melanin concentration is very low

A

blue

74
Q

The eyes appear __________ when its melanin concentration is moderate.

A

Green

75
Q

The iris is made up of contractile muscles that surround an opening called __________.

A

Pupil

76
Q

2 Types of muscles of the iris:

A

Circular Muscle or Sphincter Pupillae
Radial Muscle or Dilator Pupillae

77
Q

What happens when the eyes-PUPILS are directed to BRIGHT LIGHT?

A

Circular muscles contract, the pupils CONSTRICT

78
Q

What happens when the eyes-PUPILS are directed to DIM LIGHT?

A

Radial muscles contract, the pupils DILATE

79
Q

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

A

Retina

80
Q

It contains the photoreceptors.

A

Retina

81
Q

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

A

Optic Disc

82
Q

Bundled together with the optic nerve are the two blood supply:

A

Central Retinal Artery
Central Retinal Vein

83
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

84
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

85
Q

Three distinct layers of retinal neurons:

A

Photoreceptor Layer
Bipolar Layer
Ganglion Cell Layer

86
Q

Two types of cells present in the bipolar cell layer:

A

Horizontal cells
Amacrine cells

87
Q

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

A

Photoreceptors

88
Q

Each retina has about _________ cones and ___________ rods.

A

6 million cones
120 million rods

89
Q

20x more than cones. They very sensitive to light (have low light threshold). It can function in very dim light but they do not provide color vision (specialized for black & white vision in dim light).

A

Rods

90
Q

It allow us to see in dim light, such as moonlight.

A

Rods

91
Q

Rods is most abundant toward the edge of the retina, thus providing _____________.

A

Peripheral Vision

92
Q

Photopigment found in Rods.

A

Rhodopsin

93
Q

Composition of the photopigment Rhodopsin:

A

Scotopsin and Retinal

94
Q

It is responsible for COLOR VISION and function best in bright light.

A

Cones

95
Q

Loss of cones results to…

A

Legal Blindness

96
Q

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

A

Color Blindness

97
Q

inability to see well at dim light.

A

Night Blindness or Nyctalopia

98
Q

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

A

Carotenoid

99
Q

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

A

Macula Lutea

100
Q

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

A

Central Fovea or Fovea Centralis

101
Q

ability to see images most clearly

A

Visual Acuity

102
Q

sharpness of vision

A

Resolution

103
Q

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 - Blind Spot

104
Q

is the bending of light as it passes from one medium to another.

A

Refraction

105
Q

is a process by which the lens of the eye changes in shape/curvature to adjust for vision at various distances; the lens either increase/decrease in its curvature.

A

Accommodation

106
Q

Four Media of Refraction:

A

Cornea
Aqueous Humor
Lens
Vitreous Humor

107
Q

is the crossing point of light rays

A

Focal Point

108
Q

is the process of causing light to converge (bend toward each other).

A

Focusing

109
Q

3 REQUIREMENTS for ACCOMMODATION:

A

Change in Shape of the Lens
Constriction or Dilation of Pupils
Convergence of the Eyes

110
Q

When convergence is not complete, it produces double vision also known as…

A

Diplopia

Special Senses (2 decks)

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