eye lectures Flashcards
1
Q
What is lysozyme in tears?
A
protective bactericidal enzyme
2
Q
where is the retina located?
A
the posterior three-quarters of the inner layer of the eyeball
3
Q
what is the tarsal plate?
A
a fold of connective tissue that gives form to the eyelids
4
Q
what is the function of tarsal glands?
A
elongated, modified sebaceous glands that secrete a fluid that helps keep the eyelids from adhering to each other
5
Q
what does intraocular pressure do?
A
maintains shape of eye and prevents it from collapsing
6
Q
an infection of the tarsal gland causes what?
A
a chalazion
7
Q
what is the cause of hyperopia (farsightedness)?
A
the eyeball is shorter than normal and the image converges behind the retina
8
Q
what is the shape of the eyeball in cases of myopia (nearsightedness)?
A
longer than normal and the image converges in front of the retina.
9
Q
Do cone pigments or rhodopsin regenerate faster?
A
cones pigments
10
Q
what is the shape of the lens when focusing on a distant object?
A
flat
11
Q
when focusing on a distant object, what is the state of the zonular fibers?
A
taut
12
Q
when focusing on a close object, what is the state of the ciliary muscles?
A
contracted
13
Q
how is hypertropia treated?
A
with a convex lens
14
Q
what are the two chambers of the eye and what divides them?
A
the anterior and posterior chamber are separated by the iris
15
Q
how do distance and convergence connect? does this change overtime?
A
the nearer the object, the greater the degree of convergence needed
the ability to converge goes down over time
16
Q
what is function of the neural layer of the retina?
A
send nerve impulses into axons that form the optic nerve
17
Q
function of aqueous humor
A
nourishes the lens and cornea
18
Q
what is light adaption and how fast does it take?
A
when you go from dark to light, seconds
19
Q
what causes blood shot eyes?
A
dilation and congestion of the blood vessels of the bullbar conjunctiva
20
Q
what is the shape of the lens when focusing on something close?
A
more spherical
21
Q
function of the retina
A
receives light and converts it into receptor potentials and nerve impulses. output to the brain via axons of ganglion cells which form the optic nerve
22
Q
what is the most common form of color blindness
A
red-green
23
Q
what do the pretectal nuclei control?
A
pupillary and accomadation reflexes
24
Q
what is an astigmatism caused by?
A
the cornea or the lens or both have an irregular curve. causes blurred or distorted vision
25
function of the cornea
admits and refracts light, also protection
26
function of the choroid
provides blood supply and absorbs light
27
in what way are images projected into the eye?
inverted and left to right reversed
28
function of the vitreous chamber
contains vitreous body that helps maintain the shape of the eyeball and keeps retina attached to the choroid
29
what are the two types of conjunctiva and where are they located?
palpebral conjunctiva-inside of the eyelids
| bulbar conjunctiva- covers the sclera
30
what does the fibrous tunic contain?
the cornea and the sclera
31
what is the function of the cornea?
focus light on the retina
32
function of the anterior cavity
contains aqueous humor that helps maintain the shape of the eyeball and supplies oxygen and nutrients to the lens and cornea
33
what do rods contain?
rhodopsin
34
what is the function of glutamate?
inhibits bipolar cells from transmitting signals to ganglion cells
35
what two structure is the posterior chamber between?
behind the iris and in front of the lens
36
what is the function of the iris?
controls the size of the pupil based on autonomic reflexes
37
What are the 5 accessory structures of the eye?
eyelids, eyelashes, eyebrows, lacrimal apparatus, and extrinsic eye muscles
38
where do the axons of the eye's ganglion cells exit?
the axons exit as the optic nerve
39
What is the direction of the nerve impulse in the layers of the retina
photoreceptors->outer synaptic layer->bipolar cells->inner synaptic layer->ganglion cells->optic disc->optic nerve
40
what does the lacrimal caruncle contain?
sebaceous glands and sweat glands
41
what is the function of the extrinsic eye muscles
moving the eyeball in all directions
42
what are the six extrinsic eye muscles?
superior rectus. inferior rectus, lateral rectus, medial rectus, superior oblique, and inferior oblique
43
what are the two parts of the ciliary body?
ciliary processes and ciliary muscle
44
what is convergence?
the medial movement of the two eyeballs so that both are directed toward the object being viewed
45
What are three common retinal diseases in the elderly?
macular degeneration, detached retina, and glaucoma.
cataracts is also common in the elderly
46
what is the function of tarsal/meibomian glands and where are they located?
keeps the eyelids from sticking together
| the tarsal plate
47
Describe the cyclical process of photopigment response to light
1. in darkness retinal has a bent shape called cis-retinal which fits in the opsin portion of the photopigment
2. When cis-retinal absorbs a photon, it straightens out to trans-retinal
This change in shape is called isomerization and is the first step in visual transduction
3. After this isomerization, some chemicals form and then disappear which lead to the production of a receptor potential
4. after about a minute, the trans-retinal completely separates from opsin. It becomes colorless (bleaching)
5. an enzyme called retinal isomerase converts trans to cis
6.the cis retina binds to optin again and reforms a function photopigment (regeneration)
48
Why does crying produce a runny nose?
tears flowing down through the nasolacrimal duct into the nose
49
what is the iris and what determines it's color?
colored portion of the eyeball
| the amount of melanin in it
50
function of the lens
refracts light
51
what is the other name for the vascular tunic?
uvea
52
functions of choroid
provides nutrients to posterior surface of retina and contains melanocytes that produce melanin that make the layer seem dark brown. The melanin absorbs stray light rays and prevents reflection and scattering of light within the eyeball.
53
what is the function of the vitreous humor
holds retina against choroid giving the retina an even surface
54
what is the name for a normal eye?
emmetropic
55
What happens when bright light stimulates the eye?
parasympathetic fibers of the oculomotor nerve stimulate the circular muscles of the iris to contact and decrease the size of the pupil
56
how often is aqueous humor replaced?
every 90 minutes
57
What cranial nerve supplies the lacrimal glands?
parasympathetic fibers of the facial nerve (7)
58
What is contained in the fibrous tunic?
anterior cornea
| posterior sclera
59
the function of the suprachiasmatic nucleus?
patterns of sleep
60
function of the lacrimal apparatus?
production of tears
61
what is the pathway of visual impulses through the brain?
optic nerve->optic chiasm (cross over)->optic tract->lateral geniculate nucleus of the thalamus->optic radiation->primary visual area in occipital lobe
62
functions of the sclera
covers the entire eyeball except the cornea
gives shape to the eyeball
protects its inner parts
serves as a site for attachment for eye muscles
63
what is the pigmented layer
a sheet of melanin-containing epithelial cells which help the retina absorb stray light
64
What two structures is the anterior chamber between?
the iris and the cornea
65
function of horizontal and amacrine cells
modify the signals being transmitted along the pathway from photoreceptors to bipolar cells to ganglion cells
66
contents of vitreous humor
water, collagen fibers, and hyaluronic acid. also contains phagocytic cells that remove debris
67
what is the center of the retina?
macula lutea
68
when focusing on a distant object, what state are the ciliary muscles?
relaxed
69
where is the image projected?
fovea centralis, vision is the sharpest there
70
what is the function of the eyebrows and the eyelashes?
Protect the eyes from perspiration, foreign objects, and direct rays of the sun
71
what is the anterior chamber filled with?
aqueous humor
72
what is the tarsal plate?
a thick fold of connective tissue that forms and supports the eyelids
73
where does information go after the photoreceptors?
flows through the outer synaptic layer to bipolar cells through the inner synaptic layer to ganglion cells
74
function of the ciliary muscle
alters the shape of the lens for adaption to near or far vision by pulling on the zonular fibers
75
what volume of tears does a lacrimal gland produce per day?
1 mL
76
how does light pass through the retinal cell layers
ganglion cell layer->inner synaptic layer->bipolar cells-> outer synaptic layer-> photoreceptor layer
77
what is the first step of visual transduction?
absorption of light by a photopigment which leads to the production of a receptor potential
78
what is the posterior chamber filled with?
aqueous humor
79
what is the science name for the eyelid?
palpebrae
80
what do the superior colliculi control?
extrinsic eye muscles
81
what are the functions of the palpebrae?
shade eyes during sleep, protect eyes from excessive light and foreign objects, and spread lubricating secretions over eyeballs
82
what do cones contain?
red, blue, and green photopigments
83
what are the two photoreceptors?
rods and cones
84
what is dark adaption and how long does it take?
moving from light to dark area, takes minutes
85
what does the blind spot not contain
rods or cones
86
what are the three systems that process visual signals?
processing shape
processing color
processing movement, location, and spatial organization
87
what do all photopigments contain?
a glycoprotein called opsin and a vitamin A derivative called retinal
88
what three structures make up the vascular tunic?
choroid, ciliary body, and iris
89
What types of tissue make up the three layers of the cornea?
Outer layer: nonkeratinized stratified squamous epithelium
middle layer (stroma): collagen fibers and fibroblasts
inner layer: simple squamous epithelium
90
What do rods release in darkness?
glutamate
91
what causes a stye?
infection in the ciliary glands
92
what is the function of horizontal cells?
assist in the differentiation of various colors
93
What is the size of an adult eyeball?
2.5cm
94
how is myopia corrected?
with a concave lens
95
What is the sclera made of?
dense connective tissue made of collagen fibers and fibroblasts
96
what is dacryocystitis?
infection of the lacrimal sacs
97
how does convergence happen?
coordinated action of the extrinsic eye muscles
98
What wavelengths are visible to the eye?
400-700nm
99
explain the path of light into the eye
cornea->anterior chamber->pupil->posterior chamber->lens->vitreous humor_> projected onto the retina
100
what is the posterior CAVITY filled with?
vitreous humor
101
does the ciliary body contain melanin?
yes
102
what does the fovea centralis contain?
only cones
103
functions of tears
cleans, protects, lubricates, and moistens the eyeball
104
function of ciliary processes?
secretes aqueous humor
105
function of canal of schlemm
aqueous humor drains into it
106
how are images projected onto the retina?
images are inverted and right to left reversed due to refraction; the brain corrects the image
107
where is the poster CAVITY/vitreous chamber located?
behind the lens
108
when focusing on a close object, what is the state of the zonular fibers?
loose
109
what is the name for the point which the optic nerve exits the eye
optic disc or blind spot
110
what are the two (3?) tunics
fibrous tunic
vascular tunic
nervous tunic? (in the lab slides)
111
what does the vascular tunic contain
the choroid, ciliary body, and iris
112
why is cone vision sharper?
cones only synapse with one bipolar cell
113
in the fetus, what does the hyaloid canal hold?
hyaloid artery
114
What does the pigmented layer of the retina near the photoreceptors store?
vitamin A which contributes to regeneration in rods
115
function of the sclera
provides shape and protects inner parts
116
More than half of the sensory receptors in the human body are located in the eye? True or false
true
117
what is in the center of the macula lutea
fovea centralis, the area of the highest visual acuity
118
what is the function of amacrine cells?
synapse with ganglion cells and transmit excitatory signals to ganglion cells to initiate nerve impulses
119
what is the function of rods?
see in dim light
120
what is the conjuntiva?
A thin, protective mucous membrane made of non-keratinized stratified squamous epithelium with numerous goblet cells that is supported my areolar connective tissue
121
describe vitreous humor
a transparent, gelatinous substance
122
what do horizontal cells do?
transmit inhibitory signals to bipolar cells in the areas lateral to excited rods and cones
123
what are the two layers of the retina/nervous tunic?
pigmented layer and neural layer
124
what is the function of cones?
see in color
125
function of the ciliary body
secretes aqueous humor and alters the shape of the lens for near or far visions (accommodation)
126
Function of ciliary glands?
Release lubricating fluid into the follicles (sebaceous)
127
What should the pressure in the eye be?
16mmHg
128
function of the iris
regulates the amount of light that enters the eyeball
129
what is the funtcion of the palpebral muscles?
control eyelid movement
130
describe aqueous humor
a clear, watry liquid
131
How does visual information travel in terms of sides?
right half of each visual field goes to the left side of the brain and vice versa
