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physiological Optics Mid > Pre Finals > Flashcards

Pre Finals Flashcards

imemorise

1
Q

the ability of the eye to adjust its focal length

A

Accommodation

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2
Q

a condition in which the lens of the eye becomes progressively unable to focus on objects close to the viewer

A

Presbyopia

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3
Q

This acts like a shutter of a camera.

A

Iris

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4
Q

In the middle of a normal iris is the

A

Pupil

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5
Q

It is an opening that, typically, is circular and is comparable to the aperture of a camera.

A

Pupil

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6
Q

It helps regulate the amount of light passing through to the retina

A

Pupil

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7
Q

As the amount of light entering the eye diminishes, the iris dilator muscle pulls away from the center, causing the pupil to ______

A

Dilate

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8
Q

When too much light is entering the eye, the _______ pulls toward the center, causing the pupil to “constrict” and allowing less light to reach the retina.

A

Iris sphincter muscle

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9
Q

encircles the pupil

A

Iris sphincter muscle

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10
Q

runs radially through the iris like spokes on a wheel

A

iris dilator muscle

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11
Q

When too much light is entering the eye, the iris sphincter muscle pulls toward the center, causing the pupil to _____ and allowing less light to reach the retina.

A

Constrict

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12
Q

When too much light is entering the eye, the iris sphincter muscle pulls toward the center, causing the pupil to constrict and allowing less light to reach the ____.

A

Retina

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13
Q

________ also occurs when the crystalline lens accommodates (changes focus) so that the eye can view something at a near distance. This reaction is known as the “near reflex.”

A

Constriction of the pupil

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14
Q

Also known as NEAR REFLEX

A

Constriction of the pupil

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15
Q

A representation of parasympathetic pathways in the pupillary light reflex can be seen here

A

parasympathetic response.

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16
Q

when the crystalline lens accommodates (changes focus)

A

Near reflex

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17
Q

is an aperture of the iris situated a little towards the nasal side of the iris center.

A

Pupil

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18
Q

Shapes of the pupil for humans

A

Circular

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19
Q

Shapes of the pupil for

Horses

A

Oval

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20
Q

Shapes of the pupil for cats

A

elliptical

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21
Q

This adjustment in the lens, known as _______, is necessary for bringing near and far objects into focus.

A

Accommodation

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22
Q

The process of bending light to produce a focused image on the retina is called _____.

A

Refraction

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23
Q

Ideally, the light is “refracted,” or redirected, in such a manner that the rays are _____ into a precise image on the retina.

A

Focused

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24
Q

Light entering the eye is first bent, or refracted, by the _______

A

Cornea

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25
the clear window on the outer front surface of the eyeball.
Cornea
26
It provides most of the eye’s optical power or light-bending ability.
Cornea
27
After the light passes through the cornea, it is bent again — to a more finely adjusted focus — by the ______ inside the eye.
crystalline lens
28
The ____ focuses the light on the retina. This is achieved by the ciliary muscles in the eye changing the shape of the _____, bending or flattening it to focus the light rays on the retina.
Crystalline lens
29
Our ability to see starts when light reflects of an object at which we’re looking and enters the eye. As it enters the eye, the light is ______.
unfocused.
30
The first step in seeing is to focus the ______ onto the retina, which is a light-sensitive layer found inside the eye. Once the light is focused, it stimulate cells to send millions of electrochemical impulses along the optic nerve of the brain. The portion of the brain at the back of the head interprets the impulses enabling us to see the object.
Light rays
31
The first step in seeing is to focus the light rays onto the ____
Retina
32
a light-sensitive layer found inside the eye. | .
Retina
33
Once the light is ______, it stimulate cells to send millions of electrochemical impulses along the optic nerve of the brain.
Focused.
34
True or false: The portion of the brain at the back of the head interprets the impulses enabling us to see the object.
True
35
T or F: Even with the light focused on the retina, the process of seeing is not complete.
True
36
Even with the light focused on the retina, the process of seeing is not complete. For one thing, the image is inverted, or upside down. Light from the various “pieces” of the object being observed stimulate nerve endings — photoreceptors or cells sensitive to light — in the retina.
Sensory interpretation
37
are mainly found in the peripheral retina and enable us to see in dim light and to detect peripheral motion.
Rods
38
They are primarily responsible for night vision and visual orientation.
Rods
39
Are principally found in the central retina
Cones
40
provide detailed vision for such tasks as reading or distinguishing distant objects.
Cones
41
They are necessary for color detection
Cones
42
These photoreceptors convert light to _____ that are transmitted via the nerves to the brain.
electrochemical impulses
43
Millions of _____ travel along the nerve fibers of the optic nerve at the back of the eye, eventually arriving at the visual cortex of the brain, located at the back of the head. Here, the electrochemical impulses are unscrambled and interpreted. The image is re-inverted so that we see the object the right way up.
impulses
44
T or F: The “sensory” part of seeing is much more complex than the refractive part — and therefore is much more difficult to influence accurately.
True
45
Is a complex peripheral nervous mechanism composed of many elements
Retina
46
It is functional coat of the eye
Retina
47
Retina came from the word “______” which means “network”
Rete
48
a network of neurons-visual cells, bipolar cells and ganglionic cells
Rete/ retina
49
An innermost layer which is a thin (0.1-0.5mm) transparent membrane
Retina
50
It is attached to the underlying choroid only at the optic disc and ora serrata
Retina
51
It is where the images are cast: acts as a screen of the eye.
Retina
52
How thin is your retina
0.1-0.5mm
53
Whats inside the retina
Rods and cones
54
These two are light-sensitive cells which numbers up 120million or 6million, respectively.
Rods ans cones
55
Pigments in the ____ can absorb a very small amount of light that reaches the retina.
Rods
56
The pigment in the rod is called ____
rhodopsin
57
or visual purple.
Rhodopsin
58
It enables the eye to see shades of gray.
Rhodopsin
59
There are three types of pigments found in the rods and cones.
Cyanolabe- absorbs blue light Chlorolabe- absorbs green light Eryhtrolabe- absorbs red lab
60
The three pigments enables us to see more than how many colors?
200 colors
61
responsible for the sharp images we see
Fovea
62
located around the center of retina
Macula
63
responsible for peripheral vision which allows us to see our side without turning our heads or eyes
Macula
64
most rods are located in this area because of their higher ability to detect dark
Macula
65
All cones and rods are connected to separate nerve ending which later meet in the ____
Optic nerve
66
This nerve serves as a link between brain and eye. This makes it seem that the retina is an extension of the brain itself.
Optic nerve
67
Sometimes when we look at things, our eyes fail to see a part of the object. We hit our _____
Blind spot
68
the area where there are no rods and cones.
Blind spot
69
Here, no image is formed
Blind spot
70
T or F: we cannot see the blind spot because the image line of the blind spot of one eye deceive the other. Therefore, both blind spot are covered.
True
71
A small depression in the center of the disc, where CRA enters and the CRV leaves in the eye
Physiological Cup
72
Are found only nerve fibers | Absence of the retina renders this spot incapable of receiving impression of light known as blind spot (Mariotte’s spot)
Optic Disc
73
Mariotte’s spot
Blind spot
74
punctum caecum
Blind spot
75
3 Nerve Sheaths
Dura Arachnoid PIA
76
3.0-3.5mm, fibers from the ganglionic cells on reaching the surface of the rising bend at right angles & course over the retina to reach the optic disc
Optic Nerve
77
Size of optic nerve
3.0- 3.5mm
78
In small bundles they pass out of the eyeball through the lamina cribrosa in the scleral canal
Optic nerves
79
- from the ganglionic cell layer to their exit through the canal
Non-medullated fibers
80
- after passage through candles but they are devoid of neural
Medullated
81
A dentate line about 8.5mm back of the sclera-corneal junction.
ORA SERRATA
82
Ora means
Margin
83
Serra means
A saw
84
in the center of macula the retina is very much thinned down (0.1 mm) giving rise to a little pit or depression displacement by the bipolar cells and ganglionic neurons towards the periphery of the macula, drawing only the visual cells layer
FOVEA CENTRALIS
85
Retinal area of greatest visual acuity (in daylight vision)
Fovea centralis
86
the yellow spot- lying about 3.0 mm to the temporal side of the optic disc
MACULA LUTEA
87
measures about 1-3.0 mm in diameter
Macula lutea
88
yellowish due to the yellowish pigment (xanthophylls) in the bipolor cells & ganglionic layers
Macula lutea
89
Special parts of the retina
``` Macula lutea Fovea centralis Ora serrata Optic nerve Optic disc Physiological cup ```
90
the most interesting of all optical instruments.
Eye
91
remarkable in how it forms images and in the richness of detail and color it can detect.
Eye
92
However, our eyes commonly need some correction, to reach what is called "normal” vision, but should be called ______ rather than normal.
Ideal
93
Image formation by our eyes and common vision correction are easy to analyze with the ______
Optics
94
The ____ of the eye adjusts its power to produce an image on the retina for objects at different distances.
Lens
95
has the greatest density of light receptors and the greatest acuity (sharpness) in the visual field.
Fovea
96
The center of the image falls on the ____
Fovea
97
variable opening of the eye
Pupil
98
T or F: Our eyes perform a vast number of functions, such as sense direction, movement, sophisticated colors, and distance.
True
99
Processing of visual nerve impulses begins with interconnections in the retina and continues in the _____
Brain
100
The biggest change in the refractive index, and bending of rays, occurs at the _____ rather than the lens.
Cornea
101
The process of adjusting the eye’s focal length is called .
Accommodation
102
A person with normal (ideal) vision can see objects clearly at distances ranging from _____ to essentially infinity.
25 cm
103
T or F: The eye is most relaxed when viewing distant objects, one reason that microscopes and telescopes are designed to produce distant images.
True
104
Vision of very distant objects is called ____, while close vision is termed accommodated, with the closest vision being ______.
Totally relaxed Fully accommodated
105
Yellowish pigment in the macula lutea
Xanthophylls
106
Millions of impulses travel along the nerve fibers of the optic nerve eventually arriving at the ______
Visual cortex of the brain
107
Here, the electrochemical impulses are unscrambled and interpreted. The image is re-inverted so that we see the object the right way up
Visual cortex of the brain
108
How many rods are there
Upto 120million
109
How many cones are there
Upto 6million
110
Enables the eye to see shades of gray
Rhodopsin/ visual purple

physiological Optics Mid (2 decks)

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