Vision Flashcards
1
Q
The act of seeing
A
Vision
2
Q
More than ________ the sensory receptors in the human body are loacated in the eyes.
A
half
3
Q
List the accessory structures of the eye
A
eyebrows
eyelashes
eyelids
lacrimal apparatus
extrinsic eye muscles
4
Q
It protects the eyes from foreign objects, from perspiration and direct rays from the sun.
A
Eyebrows and eyelashes
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)
6
Q
The space between the upper and lower eyelids that exposes the eyeball.
A
Palpebral fissure
7
Q
What are the angles in the palpebral fissure?
A
Lateral commissure
Medial commissure
8
Q
This angle in the palpebral fissure is narrower and closer to the temporal bone.
A
Lateral commissure
9
Q
This angle in the palpebral fissure is broader and nearer the nasal bone.
A
Medial commissure
10
Q
In the medial commissure is a small, reddish elevation, which contains sebaceous (oil) gland and sudoriferous (sweat) glands.
A
Lacrimal caruncle
11
Q
A thick fold of connective tissue that gives form and support to the eyelids.
A
Tarsal plate
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
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
14
Q
Lines the inner aspect of the eyelids.
A
Palpebral conjunctiva
15
Q
Passes from the eyelids onto the surface of the eyeball, where it covers the sclera but not the cornea.
A
Bulbar conjunctiva
16
Q
Group of structures that produces and drains lacrimal fluid or tears in a process called lacrimation
A
Lacrimal Apparatus
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
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
19
Q
These are 2 small ducts connected with to each lacrimal punctum.
A
Lacrimal Canals/ canaliculi
(superior & inferior lacrimal canal)
20
Q
It is the expanded portion of the nasolacrimal duct.
A
Lacrimal Sac
20
Q
It is the expanded portion of the nasolacrimal duct.
A
Lacrimal Sac
21
Q
It carries the lacrimal fluid into the nasal cavity.
A
Nasolacrimal Duct
22
Q
Flow of Tears
A
- LACRIMAL GLAND secretes tears into
- LACRIMAL DUCTS, which distribute tears over the surface of eyeball
- SUPERIOR OR INFERIOR LACRIMAL CANALICULI drain tears into
- LACRIMAL SAC, which drains tears into
- NASOLACRIMAL DUCT, which drains tears into
- Nasal Cavity
23
Q
Composition of the lacrimal fluid or tears
A
Salts
Mucus
Lysozyme
24
What are the functions of the lacrimal fluid
Protection
Cleans
Lubricates
Moistens
25
How much lacrimal fluid is produced per day in each lacrimal gland.
1mL
26
What do you call the bony depressions of the skull wherein the eyes sit?
Orbits
27
Help protect the eyes, stabilize them in three dimensional space, and anchor them to the muscles that produce their essential movements.
Orbits
28
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 __________________.
Periorbital fat
29
What are the six extrinsic eye muscles?
Superior rectus
Inferior rectus
Medial rectus
Lateral rectus
Superior oblique
Inferior oblique
30
Extends from the walls of the bony orbit to sclera of the eye.
Extrinsic eye muscles
31
What supplies the six extrinsic eye muscles?
oculomotor (III)
trochlear (IV)
or abducens (VI) nerves
32
Turns the eye upward
Superior rectus
33
Turns the eye downward
Inferior rectus
34
Towards the midline
Medial rectus
35
Towards the lateral side
Lateral rectus
36
These muscles preserve the rotational stability of the eyeball.
Oblique muscles
37
Rotates the eyeball so the cornea turns in a downward and outward direction.
Superior Oblique
38
Rotates the eyeball so the cornea turns in a upward, outward direction.
Inferior Oblique
39
The diameter of eyeball
2.5 cm (1 inch)
40
Of the total surface of the eyeball, how much is exposed?
1/6
41
Bony pyramidal shaped cavity of the skull that holds the eyeball.
Orbit
42
Enumerate the 3 layers/tunics of the eyeball,
Fibrous tunic
Vascular tunic/Retina
Nervous tunic
43
The superficial layer of the eyeball and consists of the anterior cornea and posterior sclera outer later and it is AVASCULAR.
Fibrous tunic
44
It is a transparent coat that covers the colored iris. It is located on the anterior portion and has no capillaries.
Cornea
45
What composes the outer surface of the cornea?
Nonkeratinized stratified squamous epithelium
46
What composes the middle coat of the cornea?
collagen fibers and fibroblasts
47
What composes the inner surface of the inner surface of the cornea?
simple squamous epithelium
48
Permits light to enter the eye (bend/refracts light)
Cornea
49
The "white" of the eye, is a layer of dense connective tissue made up of collagen fibers and fibroblasts.
Sclera
50
Covers the entire eyeball except the cornea.
Sclera
51
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.
Sclera
52
What cranial nerve pierces the posterior portion of sclera?
Optic (CN II)
53
An opening located at the junction of the sclera and cornea. Aqueous humor (a fluid) drains into this sinus.
Canal of Schlemm or Scleral Venous Sinus
54
The middle layer of the eyeball. It contains lots of blood vessels.
Vascular tunic/ Uvea
55
What are the three parts of the vascular tunic?
Choroid
Ciliary body
Iris
56
It is the posterior portion of the vascular tunic, lines most of the internal surface of the sclera.
Choroid
57
Its numerous blood vessels provide nutrients to the posterior surface of the retina.
Choroid
58
What causes the vascular layer to appear dark brown in color?
Melanin (produced by melanocytes)
59
Absorbs stray light rays, which prevents reflection and scattering of light within the eyeball.
Melanin
60
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
Ciliary body
61
Protrusions or folds on the internal surface of the ciliary body. They contain blood capillaries that secrete aqueous humor.
Ciliary process
62
Extending from the ciliary process are _________________ or suspensory ligaments that attach to the lens.
Zonular fibers
63
The jagged anterior margin of the retina.
Ora serrata
64
Is a circular band of smooth muscle.
Ciliary muscle
65
Lens is relatively flat
Distant vision
66
Lens bulges/increases in curvature
Near vision
67
The hole in the center of the iris
Pupil
68
Heavily pigmented back of the eye
Choroid and retina
69
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.
20
70
This reduces tension on the suspensory ligaments of the lens, allowing the lens to assume a more spherical form.
Near vision
71
It is flexible, biconvex, transparent disc (crystal clear).
Lens
72
Composition of the lens
65% water
35% CHON
73
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.
Crystallins
74
Helps focus images on the retina to facilitate clear vision.
Lens
75
Principal refractive medium (fine-tunes light rays onto the retina to facilitate clear vision)
Lens
76
What divides the interior of the eyeball into two cavities?
Lens
77
What are the two cavities of the interior of the eyeball?
Anterior cavity
Posterior cavity
78
The space anterior to the lens
Anterior cavity
79
2 chambers of the anterior cavity
Anterior chamber
Posterior chamber
80
Lies between cornea and iris
Anterior chamber
81
Lies behind the iris and in front of the zonular fibers and lens
Posterior chamber
82
The anterior cavity is filled with ______________________.
Aqueous Humor
83
A clear, watery fluid with similar composition as the CSF.
Aqueous Humor
84
The larger posterior cavity of the eyeball.
Vitreous chamber
85
Composed of 99% water, it is transparent, jelly-like substance. Also contains phagocytic cells that remove debris, keeping the post cavity clear
Vitreous Humor
86
4 major functions of vitreous humor
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
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.
Hyaloid Canal
88
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.
Iris
89
It consists of melanocytes and circular and radial smooth muscle fibers. The amount of melanin in this part determines the eye color.
Iris
90
It regulates the amount of light entering the eyeball through the pupil.
Iris
91
The hole in the center of the iris.
Pupil
92
What are the two types of muscles of the iris?
-Circular muscle or sphincter pupillae
-Radial muscles or dilator pupillae
93
The innermost layer of the eyeball
Nervous tunic/Retina
94
The inner coat of the eyeball, lines the posterior three-quarters of the eyeball and is the beginning of the visual pathway.
Retina
95
It contains the photoreceptor
Retina
96
The only structure in the body where blood vessels can be visualized thru and ophthalmoscope.
Retina
97
The only structure in the body where blood vessels can be visualized thru and ophthalmoscope.
Retina
98
The site where the optic (II) nerve exits the eyeball.
Optic disc
99
What bundles with the optic nerve?
Central retinal artery
Central retinal vein
100
Fan out to nourish the anterior surface of the retina.
Central retinal artery
101
Drains blood from the retina through the optic disc.
Central retinal vein
102
What are the layers of the retina?
Pigmented layer
Neural layer
103
The non-visual portion. It is a sheet of melanin-containing epithelial cells located between the choroid and the neural part of the retina.
Pigmented layer
104
Absorbs stray light rays thus preventing reflection and scattering of light within the eyeball, allowing sharp and clear image.
Melanin
105
It is a multilayered outgrowth of the brain that processes visual data extensively before sending nerve impulses into axons that form the optic nerve.
Neural layer/Sensory retina
106
Three distinct layers of the retinal neurons
Photoreceptor layer
Bipolar cell layer
Ganglion cell layer
107
Are specialized cells in the photoreceptor layer that begin in the process by which light rays are ultimately converted to nerve impulses.
Photoreceptors
108
Two types of photoreceptors
Rods and cones
109
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.
Rods
110
How many rods does each retina have?
120 million rods
111
How many cones does each retina have?
6 million cones
112
It is most abundant toward the edge of the retina, thus providing PERIPHERAL VISION.
Rods
113
It is made up of CHON (SCOTOPSIN) and a pigment (RETINAL)
Rhodopsin
114
It is responsible for color vision and function best in bright light.
Cones
115
The loss of cones produces _____________________
Legal blindness
116
Three types of cones present in the retina
Blue cones
Green cones
Red cones
117
Inability to distinguish between certain colors because of the absence or deficiency of 1 or 3 photopigment.
Color blindness
118
Inability to see well at dim light
Night blindness/Nyctalopia
119
Good vision depends on adequate intake of _______________ -rich vegetables such as: carrots, spinach, broccoli, yellow squash, food that contain vitamin A like liver.
Carotenoid
120
Is a small yellow spot near the center of the posterior portion of the retina.
Macula Lutea
121
A small/pit depression at the center of the macula lutea. It contains only CONES, thus, the area of highest visual acuity or resolution.
Central Fovea (Fovea centralis)
122
Ability to see images clearly
Visual Acuity
123
Sharpness of vision
Resolution
124
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.
Optic disc
125
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.
Accommodation
126
The four media of refraction
Cornea
Aqueous humor
Lens
Vitreous humor
127
How many percent of the total refraction of light occurs at the cornea?
75%
128
It is the crossing point of light rays
Focal point
129
The process of causing light to converge (bend toward each other)
Focusing
130
Characteristics of images focused on the retina
1. Inverted/upside-down
2. They undergo right to left reversal
131
Viewing an object:
The light rays refelcted from the object are nearly parallel to one another
At 20 ft. distance
132
Viewing an object:
Light rays that are reflected from the object are divergent (they move away from each other)
Near object (Near vision)
133
3 requirements for Accommodation
1. Change in the shape of the lens
2. Constriction/dilation of the pupils
3. Convergence of the eyes
134
The minimum distance from the eye that an object can be clearly focused with maximum effort.
Near Point of Vision
135
Nearsightedness. Image is focused in front of the retina, thus the person has to move closer to the object to allow clearer vision.
Myopia
136
Causes for Myopia
Elongated eyeball and thickened lens
137
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.
Hyperopia/Hypermetropia
138
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.
Hyperopia/Hypermetropia
139
The cornea's curvature is assymetrical, so light rays are focused at 2 points on the retina, rather than one point.
Astigmatism
140
Inflammation of the conjunctiva, usually from bacterial infection.
Conjunctivitis
141
Contagious conjunctivitis
Pink eye
142
A cyst caused by infection of the sebaceous glands along the edge of the eyelids.
Chalazion
143
Infection of an eyelash/hair follicle
Stye
144
Decrease in the ability of the eye to accommodate for near vision; comes with aging.
Presbyopia
145
A defect in which the cornea or lens is not uniformly curved and the image is not sharply focused.
Astigmatism
146
Most common cause of blindness
Cataract
