Chapter 15: The Special Senses Flashcards
(131 cards)
1
Q
what is the cornea?
A
transparent area on anterior surface of the eye
2
Q
what is the pupil?
A
opening in center of the iris
3
Q
function of the pupil
A
transmits light
4
Q
what is the conjunctiva?
A
layer of mucous membrane and epithelium that lines the eyelids and anterior eye
5
Q
what are the tarsal glands?
A
modified sebaceous glands
6
Q
what is the function of tarsal glands?
A
secretions prevent eyelid from sticking
7
Q
conjunctivitis is also known as
A
pinkeye
8
Q
what is conjunctivitis?
A
inflammation of the conjunctiva
9
Q
redness of the eye in conjunctivitis is due to __
A
dialation of blood vessels deep in epithelium of conjunctiva
10
Q
what things can cause conjunctivitis?
A
infection, irritation (physical, chemical, allergic) on conjunctival surface
11
Q
function of lacrimal gland
A
makes tears
12
Q
what is the function of tears?
A
lubricate, nourish, oxygenate and clean the cornea
13
Q
lacrimal gland contains ___ and ___ that attack invading pathogens
A
lysozyme; antibodies
14
Q
what are the three tunics (layers) of the eye?
A
- outer fibrous
- middle vascular
- inner
15
Q
what is contained in the outer layer of the eye?
A
sclera and cornea
16
Q
what is contained in the middle layer of the eye?
A
iris, choroid, ciliary body
17
Q
what is contained in the inner layer of the eye?
A
retina
18
Q
what are the 3 functions of the fibrous layer of the eye?
A
- support and protect
- attachment site for extrinsic eye muscles
- curve of cornea focuses light
19
Q
light enters first through the __
A
cornea
20
Q
the vascular layer of the eye contains ___, ___ and ___
A
blood vessels; lymphatic vessels; intrinsic muscles of eye
21
Q
what are the 4 functions of the vascular layer of the eye?
A
- route for blood vessels/lymphatic to eye
- regulates amount of light (iris)
- secretes / reabsorbs aqueous humour
- controls shape of lens (ciliary body) = focus
22
Q
what is the iris/
A
coloured part of the eye
23
Q
the iris contains __ and __
A
blood vessels and pigment cells (melanocytes)
24
Q
the iris is made of 2 layers of
A
smooth muscle
25
what is the role of the smooth muscle in the iris?
contraction changes diameter of pupil to control amount of light entering
26
what is the ciliary body?
thickened region bulging into interior eye
27
___ connects ciliary body and lens
ring of fibers
28
what is the choroid?
vascular layer under the sclera
29
the choroid has an extensive __ network supplying ___ and __ to the neural layer
capillary network; oxygen/nutrients
30
function of the outer pigmented layer of the retina
absorbs light
31
the thick inner neural layer of the retina contains ____
photoreceptors
32
what are the 2 types of photoreceptors?
rods and cones
33
eye cavities are separated by ____
lens / ciliary body
34
the anterior cavity of the eye extends from __ to __
cornea to lens
35
the anterior cavity contains fluid called __
aqueous humor
36
the anterior cavity contains 2 chambers ___
1. anterior chamber
| 2. posterior chamber
37
the anterior chamber of the anterior cavity in the eye extends from the ___ to ___
cornea to iris
38
the posterior chamber in the anterior cavity of the eye extends from ___ to __
iris to ciliary body and lens
39
the posterior cavity is filled with gelatinous ___
vitreous body
40
what is the vitreous humor?
fluid part of the vitreous body
41
what is the ciliary muscle?
smooth muscle ring that projects into the eye
42
the aqueous humor circulates within the ___ and passes through the __
anterior cavity; pupil
43
the aqueous humor is secreted by the epithelial cells of the ____
ciliary processes
44
the aqueous humor diffuses through the ___ to the ___ surface
vitreous body; retinal surface
45
the aqueous humor leaves the eye at the ___
scleral venous sinus
46
the aqueous humor flows into veins in the __
sclera
47
what are the 4 functions of the aqueous humor?
1. transports nutrients and wastes
2. forms fluid cushion
3. helps retain eye shape
4. stabilizes position of the retina
48
the body of the iris is highly __ pigmented ___ tissue
vascular; loose connective
49
eye colour is determined by genes that influence ___ and ___
density/distribution of melanocytes; density of pigmented epithelium
50
T/F the cornea is transparent and clear to allow light through
true
51
the cornea is a dense matrix of multiple layers of __-
collagen fibers
52
the cornea is ___ and receives oxygen and nutrients from ___
avascular; tears
53
what is the primary function of the lens?
changes shape to focus image on photoreceptors
54
what is the sclera?
the white of the eye
55
what is the sclera made of ?
dense fibrous connective tissue + collagen and elastic fibers
56
what are 2 functions of the sclera?
1. stabilizes eye shape during movement
| 2. insertion for extrinsic eye muscles
57
function of the optic nerve
conveys visual information to brain
58
what are 2 functions of the ciliary body?
1. supports lens
| 2. controls lens shape
59
____ helps resist the urge of the lens to ball up
tension in ciliary zonule
60
the retina contains what 4 things?
1. photoreceptors
2. pigent cells
3. supporting cells
4. neurons
61
the two pupillary muscles of the iris are
1. dialator pupillae muscles
| 2. sphincter pupillae muscles
62
formation of dilator pupillae muscles around pupil
extend radially
63
the dilator pupillae muscles are innervated by the ___ nervous system
sympathetic
64
formation of sphincter muscles around pupil
encircle pupil
65
the sphincter pupillae muscles are innervated by the ___ nervous system
parasympathetic
66
what is the macula?
patch of retina with lots of photoreceptors
67
the fovea centralis is the central part of the __
macula
68
the highest concentration of photoreceptors (sharpest image) is found in the ___
fovea centralis
69
explain how light is focused in the eye
1. light is refracted when it comes in through the cornea and again through aqueous humor into lens and is bent towards focal point
70
the focal point is a specific point on the __
retina
71
the focal distance of a lens is the distance between the center of __ and its ___
lens; focal point
72
the focal distance is determined by two things __ and __
1. distance form object to lens
| 2. shape of lens
73
T/F the distance from lens to retina can change
false
74
eyes focus by changing ___ ( a process called __ )
changing shape of the lens; accommodation
75
for close vision; the ciliary muscle _____ (contracts/relaxes) and moves ____ (towards/away) and ____ (increases/decreases tension in ciliary zonule
contracts; towards; decreases
76
for distant vision; the cilary muscle ___ and the ciliary zonule ___ on lens
relaxes; pulls
77
for close vision, the lens is pulled into a ___ shape
spherical
78
the spherical shape of the lens increases __
refraction
79
for distant vision, the shape of the lens is __-
flattened
80
what is the near point of vision?
inner limit of clear vision
81
the near point of vision is determined by __
lens elasticity
82
the near point of vision ___ with age
increases
83
what is the function of the pigmented layer of the retina
prevents visual echoes by absorbing light
84
what is the site of preliminary processing/integration of visual info?
neural layer of retina
85
photoreceptors are located closest to the ___ layer
pigmented
86
rods are highly ___
sensitive
87
the function of rods
allow vision in dim light
88
T/F rods can distinguish colour
false
89
function of cones
colour vision, sharper, clearer images
90
cones require what kind of light?
intense
91
rods and cones synapse with ___
bipolar cells
92
bipolar cells synapse on ___
ganglion cells
93
what is the innermost layer of the retina?
ganglion cells
94
axons of ganglionic cells converge at the ___ to form the optic nerve
optic disc
95
what is the blind spot?
where the optic nerve leaves the eye
96
blood vessels follow the ___ to supply inner neural layers
optic nerve
97
cones are most dense at the ___
fovea centralis of the macula
98
are there rods located in the fovea centralis?
no
99
cone density directly correlated to ___
visual acuity
100
maximum density of rods s located at ___
periphery
101
the visible light spectrum
400-700 nm
102
rods respond to ___ wavelengths
blue-green
103
what are the 3 types of cones?
1. blue cones
2. green cones
3. red cones
104
what is the most abundant type of cones?
red cones
105
if all three cone types are stimulated, what colour do we see?
white
106
colour blindness is caused by __
nonfunctional or absent cones
107
red-green colour blindness is caused by a lack of what type of cones?
red cones
108
describe the visual pathway
photoreceptors ---> bipolar cells ---> ganglion cells
109
the 2 optic nerves reach the diencephalon at the ____
optic chiasm
110
from the optic chiasm, continue along the ___
optic tracts
111
about half the fibers from the optic nerve go to the ___ nucleus on the ___ side of the brain and the other half to the ___ side
lateral geniculate; same side, opposite side
112
what is optic radiation?
bundle of projection fibers linking each lateral geniculate body with visual cortex on the same side
113
collaterals from fibers synapsing in lateral geniculate bodies go to subconscious processing centers in the ___ and ___
diencephalon and brainstem
114
what is depth perception?
ability to judge depth / distance by interpreting 3D relationships
115
depth perception is perceived by comparing ___ within images received by both eyes
relative positions of objects
116
T/F images form right and left eyes overlap
true
117
emmetropia is ___ vision
normal
118
in normal vision; when the ciliary muscle is relaxed and lens flattened, distant image is focused on ___
retinal surface
119
myopia is ____ vision
nearsightedness
120
in myopia, the focal distance is too ___
short
121
in myopia, the image focuses on ___
area in front of retina
122
shape of the eyeball that causes myopia
too deep (egg-shaped)
123
in myopia, the resting curvature of the eye is too ___
great
124
myopia is corrected with ___ lenses
diverging / concave
125
what is the function of concave lenses?
spreads light rays apart to shift focus onto retina
126
hyperopia is ___ vision
farsighted
127
in hyperopia, the focal distance is too __
long
128
in hyperopia, the image focuses on __
area behind the retina
129
shape of eyeball with hyperopia
too flat
130
hyperopia is corrected with ___ lenses
converging / convex
131
what is the function of convex lenses?
provides additional refraction to focus on retina
