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► Med - Anatomy & Physiology > Eye > Flashcards

Eye Flashcards

1
Q

respond to

  • touch,
  • pressure,
  • vibration,
  • stretch,
  • and itch
A

STIMULUS TYPE

Mechanoreceptors

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2
Q

sensitive to changes in temperature

-within a range

A

STIMULUS TYPE

Thermoreceptors

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3
Q

Respond to light energy

-retina in the eye

A

STIMULUS TYPE

Photoreceptors

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4
Q

Respond to chemicals

  • smell,
  • taste,
  • changes in blood chemistry
A

STIMULUS TYPE

Chemoreceptors

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5
Q

Sensitive to pain-causing stimuli

  • extreme heat or cold
  • excessive pressure
  • inflammatory chemicals
A

STIMULUS TYPE

Nociceptors

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6
Q
  • Respond to stimuli arising outside of body
  • Found near the body surface (skin)
  • -Sensitive to touch, pressure, pain and temperature
  • –ex: Merkel disc, Pacinian Corpuscle, Free nerve endings
  • Include the Special Sense Organs
  • -eye, ear, nose, taste buds
A

LOCATION TYPE

Exteroceptors

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7
Q
  • AKA: Enteroceptors, Visceroceptors
  • Respond to stimuli arising WITHIN the body
  • -Found in internal viscera and blood vessels
  • Sensitive to chemical changes, smooth muscle stretch, and core temperature changes
  • -ex: baroreceptors (blood pressure), and chemoreceptors (CO2 and H+)
A

LOCATION TYPE

Interoceptors

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8
Q
  • Respond to degree of stretch of the associated structures
  • -found in: skeletal muscles, tendons, joints, ligaments, connective tissue coverings of bones and muscles
  • Continuously inform the brain of one’s movements and position in space
  • -Ex: Muscle spindles; Golgi tendon organ
A

LOCATION TYPE

Proprioceptors

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9
Q

Receptors classified as either:

  • Simple
  • or Complex
A

STRUCTURAL COMPLEXITY

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10
Q
  • General sensory receptors

- include encapsulated and nonencapsulated varieites

A

STRUCTURAL COMPLEXITY

Simple

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11
Q

Simple receptors with free dendritic endings, include

  • Thermoreceptors
  • Nociceptors
  • Light touch receptors

ex: free nerve endings, Merkel discs, root hair plexus

A

STRUCTURAL COMPLEXITY

Simple - Nonencapsulated

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12
Q

(10º - 40º C), found in superficial dermis

A

STRUCTURAL COMPLEXITY

Cold Thermoreceptor (Simple Nonencapsulated)

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13
Q

(32º - 48º C); found in deeper dermis

A

STRUCTURAL COMPLEXITY

Heat Thermoreceptor (Simple Nonencapsulated)

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14
Q

Respond to

  • pinching,
  • inflammatory chemicals from damaged tissue,
  • temperature changes outside the range of the thermoreceptors,
  • Capsaicin
A

STRUCTURAL COMPLEXITY

Nociceptors (Simple Nonencapsulated)

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15
Q

Receptors include:

  • Merkel discs (light pressure),
  • Hair follicle receptors (light touch)
A

STRUCTURAL COMPLEXITY

Light Touch Receptors (Simple nonencapsulated)

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16
Q 
Simple receptors that ALL respond as mechanoreceptors
ex:
Meissner corpuscles
Pacinian corpuscles
Ruffini Endings
A

Encapsulated - Simple

Structural Complexity

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17
Q

-discriminative touch

A

Meissner’s Corpuscles
Encapsulated - Simple

Structural Complexity

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18
Q

deep pressure and vibration

A

Pacinian (lamellated) corpuscles
Encapsulated - Simple

Structural Complexity

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19
Q

deep continuous pressure

A

Ruffini endings
Encapsulated - Simple

Structural Complexity

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20
Q

Muscle stretch

A

Muscle Spindles
Encapsulated - Simple

Structural Complexity

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21
Q

Muscle load

A

Golgi tendon Organs
Encapsulated - Simple

Structural Complexity

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22
Q

Stretch in synovial joint capsules

A

Joint kinesthetic receptors
Encapsulated - Simple

Structural Complexity

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23
Q

Special Sense organs have ___ complexity

  • Organization is specific to special sense organ and is polysynaptic
  • Involve with:
  • -vision
  • -hearing
  • -equilibrium
  • -smell
  • -taste
A

Complex receptors

Complex receptors
Structural Complexity

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24
Q
  1. cornea
  2. aqueous humor
  3. lens
  4. vitreous humor
  5. neural layer of retina
  6. photoreceptors
A

Pathway of light entering the eye

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25
Q

majority of light refraction occurs at ____

A

cornea

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26
Q

but light refracts in these three places

A
  1. entering the cornea
  2. entering the lens
  3. exiting the lens
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27
Q

___ muscle alters lens curvature and shape to allow for fine focusing of an image

A

ciliary

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28
Q

ciliary body is attached to lens via ___

A

suspensory ligaments

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29
Q

light from a distance needs ___ refraction for proper focusing

A

very little

FOCUSING FOR DISTANCE VISION

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30
Q

the distance beyond which the lens does not need to change shape to focus
-is 20 feet in the emmetropic (normal) eye

A

Far Point of Vision

FOCUSING FOR DISTANCE VISION

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31
Q

normal eye

A

emmetropic

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32
Q

Distance vision requires (parasympathetic/sympathetic) input

A

sympathetic

FOCUSING FOR DISTANCE VISION

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33
Q

Ciliary muscles are (relaxed/taut), meaning the suspensory ligaments are (relaxed/taught) so the lens remains (flat/round) for DISTANCE vision

A

RELAXED ciliary muscle
TAUT suspensory ligaments
=flattened lens

FOCUSING FOR DISTANCE VISION

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34
Q

Light from a close object (converges/diverges) as it approaches the eye and requires active adjustments to place image at the fovea focal point

A

Diverges

FOCUSING FOR CLOSE VISION

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35
Q

=the closest point at which we can focus clearly. representing the maximum lens bulge achieveable

A

= Near point of vision

FOCUSING FOR CLOSE VISION

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36
Q

What is the near point of vision for an emmetropic eye?

A

4 inches

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37
Q

What are the three required simultaneous responses for close vision?

A
  1. Accommodation
  2. Constriction
  3. Convergence

FOCUSING FOR CLOSE VISION

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38
Q

=changing the lens shape by ciliary muscles; increases refraction

A

= Accommodation

FOCUSING FOR CLOSE VISION

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39
Q

Close vision requires (parasympathetic/sympathetic) input

A

Parasympathetic

FOCUSING FOR CLOSE VISION

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40
Q
  1. Ciliary muscles are (relaxed/taut), meaning the suspensory ligaments are (relaxed/taught) so the lens remains (flat/round) for CLOSE vision
A

Ciliary muscles taut
Suspensory ligaments loose
Lens becomes rounder
1. Accomodation

FOCUSING FOR CLOSE VISION

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41
Q
  1. =the pupillary reflex (constricts/relaxes) the pupils to prevent the most divergent light rays from entering the eyes for close vision
A

CONSTRICTS
=Constriction

FOCUSING FOR CLOSE VISION

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42
Q
  1. (Medial/Lateral) movement of the eyeballs toward the object being viewed for close vision
A

Convergence.
-Medial

FOCUSING FOR CLOSE VISION

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43
Q

-normal eyeball length and eye function with light focused properly

A

Emmetropic Eye

PROBLEMS OF REFRACTION

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44
Q
  • the FOCAL POINT is in FRONT of the retina due to a longer than normal eyeball
  • difficulty with distant vision
  • corrected with CONCAVE lens
A

Myopia (Nearsightedness)

PROBLEMS OF REFRACTION

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45
Q
  • The FOCAL POINT is BEHIND the retina due to a shorter than normal eyeball
  • difficulty with close vision
  • corrected with convex lens
A

Hyperopia (Farsightedness)

PROBLEMS OF REFRACTION

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46
Q
  • caused by unequal curvatures in different parts of the cornea or lens
  • corrected with cylindrically ground lenses, corneal implants, or laser procedures
A

Astigmatism

PROBLEMS OF REFRACTION

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47
Q

the awareness of changes in the internal and external environment

A

Sensation

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48
Q

The conscious interpretation of those stimuli

A

Perception

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49
Q

Input comes from exteroceptors, proprioceptors, and interoceptors

A

Sensory Integration

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50
Q

Input is relayed toward the brain but is processed along the way
-Known as ___
Ex: processing in the thalamus

A

Sensory Integration

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51
Q

Sensory integration involves processing at three levels

A
  1. Receptor
  2. Circuit level
  3. Perceptual level
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52
Q

sensory receptors

A

Receptor Sensory Integration

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53
Q

Ascending pathways

A

Circuit Level Sensory Integration

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54
Q

Neuronal Circuits in the Cerebral Cortex

A

Perceptual Level Sensory Integration

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55
Q

To be processed at the receptor level,

The receptor must have ___y for the stimulus energy

A

specificity

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56
Q

To be processed at the receptor level, The receptor’s ___ (area the receptor monitors) must be stimulated

A

receptive field

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57
Q

Stimulus energy must be converted into a graded potential=

A

Transduction

Processing at the Receptor Level

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58
Q

___ occurs when sensory receptors are subjected to a constant, unchanging stimulus

A

Adaptation (of Sensory Receptors)

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59
Q

Over time,

  • Receptor membranes become less responsive
  • Graded potentials decline in frequency or stop
A

Adaptation of Sensory Receptors

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60
Q

___ receptors signal the beginning or end of a stimulus, thus fast-adapting

Examples: receptors for pressure, touch and smell

A

Phasic receptors

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61
Q

___ receptors are slow-adapting or non-adapting

A

Tonic receptors

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62
Q

Slow-adapting examples of ___ receptors: Merkel discs, Ruffini endings and chemoreceptors

A

Tonic receptors

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63
Q

Non-adapting examples of ___ receptors: Pain receptors and proprioceptors

A

Tonic receptors

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64
Q

In general sense receptors, the ___ potential and ___ potential (AP generator) arethe same thing

A

receptor potential; graded potentials

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65
Q

Stimulus —> Receptor potential (graded potential –> ?

A 
General Sense Receptors
Action Potential (if threshold is reached)
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66
Q

In SPECIAL SENSE organs, there’s intermediate step involving release of neurotransmitter. This is example of ___

A

Polysynaptism

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67
Q

For Special Sense Organs,

  1. Stimulus
  2. Receptor Potential (in receptor cell)
  3. ??
A
  1. Release of Neurotransmitter
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68
Q

For Special Sense Organs,

  1. Release of Neurotransmitter
  2. ??
A
  1. Graded Potential
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69
Q

For Special Sense Organs,

  1. Graded Potential
  2. ???
A
  1. ACtion Potential (if threshold is reached)
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70
Q

Pathways of 3 neurons conduct sensory impulses upward to the appropriate brain regions

A

Processing at the Circuit Level

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71
Q

Conduct impulses from the receptor level to the second-order neurons in the CNS

A

First order neurons

Processing at the Circuit Level

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72
Q

Transmit impulses to the thalamus or cerebellum

A

Second order neurons

Processing at the Circuit Level

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73
Q

Conduct impulses from the thalamus to the somatosensory cortex

A

Third order neurons

Processing at the Circuit Level

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74
Q
  • Sensation is detected in the primary cortex related to sensory pathway
A

Processing at the Perceptual Level (Cerebral cortex circuits)

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75
Q

-Perception (conscious interpretation) in the related association cortex

A

Processing at the Perceptual Level (Cerebral cortex circuits)

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76
Q

Identification of the sensation depends on the specific location of the target neurons in the appropriate ___ cortex

A

sensory

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77
Q

conscious interpretation

A

Perception

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78
Q

Perception occurs in the related association cortex and involves
1)
2)
3)

A

1) Perceptual detection
2) Magnitude estimation
3) Spatial discrimination

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79
Q

Ability to detect a stimulus (requires a summation of impulses)

A

Perceptual Detection

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80
Q

intensity is coded in the frequency of impulses

A

Magnitude estimation

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81
Q

Identifying the site or pattern of the stimulus (studied by the two-point discrimination test0

A

Spatial discrimination

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82
Q

warns of actual or impending tissue damage

A

Perception of Pain

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83
Q

stimulus intensity where pain is first sensed by the brain

A

Pain threshold

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84
Q

Stimuli include extreme pressure and temperature, inflammatory chemicals

A

Pain threshold

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85
Q

Most potent stimuli for this are: histamine, K+, ATP, acids and bradykinin

A

pain threshold

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86
Q

Impulses for pain travel on fibers that release neurotransmitters ___ & ___

A

Glutamate

Substance P

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87
Q

individual, highly variable

A

pain tolerance

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88
Q

Blocked by inhibitory endogenous opioids (endorphins and enkephalins)

A

Pain Modulation

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89
Q

is often difficult yet critical to positive post-injury / post-op outcomes

A

Effective Pain Management

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90
Q

-can occur secondary to intense or prolonged pain

A

Chronic Pain

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91
Q

-Due to spinal cord pain amplification; must reduce signals to prevent synapse enhancement

A

Chronic Pain

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92
Q

-When the stimuli at the end of the remaining stump travels up the afferent pathway and terminates in the region of the sensory cortex mapped from the original body part

A

Phantom Limb Pain

follows amputation

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93
Q

The body part is missing, but the pathway is the same, so the brain interprets the part as present

A

Phantom Limb Pain

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94
Q

Improved by using epidural anesthesia which blocks spinal cord transmission

A

Phantom Limb Pain

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95
Q

Pain stimuli arising from the viscera are perceived as somatic in origin

A

Referred Pain

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96
Q

Visceral pain afferents travel along the same pathways as somatic pain fibers

A

Referred Pain

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97
Q

70% of all the body’s sensory receptors are in the

A

eye

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98
Q

Almost half of the cerebral cortex is involved in processing

A

visual information

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99
Q

Most of the eye is protected by a cushion of ___ and the ___

A

fat;

bony orbit

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100
Q
  1. Eyebrows
  2. Eyelids (Palpebrae)
  3. Conjunctiva
  4. Lacrimal Apparatus
  5. Extrinsic Eye Muscle
A

Protect the eye
Aid in Eye Function
Accessory Structures of the Eye

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101
Q

Coarse hairs that overlie the supraorbital margins;

shade and stop perspiration

A

Eyebrows

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102
Q

Palpebrae

A

Eyelids

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103
Q

Protect the eye anteriorly

A

Palpebrae

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104
Q

separates eyelids

A

Palpebral fissure

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105
Q

Elevation at medial commissure;

contains oil and sweat glands

A

Lacrimal caruncle

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106
Q

Internal supporting connective tissue sheet for muscle attachment

A

Tarsal Plates:

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107
Q

This muscle closes the eye

A

Orbicularis oculi muscle

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108
Q

This muscle opens the eye

A

Levator Palpebrae Superioris

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109
Q

lubricating modified sebaceous glands

A

Tarsal Glands

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110
Q

initiate reflex blinking

A

Eyelashes

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111
Q

Transparent Membrane

A

Conjunctiva

112
Q

Lines the eylids

A

Palpebral conjunctiva

113
Q

Covers the “whites” of the eyes

A

bulbar conjunctiva

114
Q

Produces a lubricating mucus secretion

-prevents drying

A

Conjunctiva

115
Q

inflammation; causes reddened, irritated eyes

A

Conjunctivitis

116
Q

Consists of the lacrimal gland and associated ducts which connect to nasal cavity

A

Lacrimal Apparatus

117
Q

Lacrimal glands secrete

A

tears

118
Q

Contain mucus, antibodies and lysozyme

A

tears

119
Q

Enter the eye via superolateral excretory ducts

A

tears

120
Q

Exit the eye medially via paired lacrimal canaliculi at the lacrimal punctum

A

tears

121
Q

Drain into the nasolacrimal duct

A

tears

122
Q

Six strap-like muscles which originate from the bony orbit

A

Extrinsic Eye Muscles

123
Q
  • Enable the eye to follow moving objects

- Help maintain the shape of the eyeball

A

Extrinsic Eye Muscles

124
Q

___ rectus muscles (common tendinous ring) & ___ oblique muscles (rotation)

A

4

2

125
Q

(moves eye laterally)

A

Lateral rectus

126
Q

Lateral rectus nerve?

A

CN VI

Abducens

127
Q

moves eye medially

A

medial rectus

128
Q

medial rectus nerve?

A

CN III

Oculomotor

129
Q

elevates eye and turns it medially

A

Superior rectus

130
Q

Superior rectus nerve?

A

CN III

Oculomotor

131
Q

depresses eye and turns it medially

A

Inferior rectus

132
Q

Inferior rectus nerve?

A

CN III

Oculomotor

133
Q

Depresses eye and turns it laterally

got the cool hook thing

A

Superior oblique

134
Q

Superior oblique nerve?

A

CN IV

Trochlear

135
Q

elevates eye and turns it laterally

A

Inferior oblique

136
Q

Inferior oblique nerve?

A

CN III

Oculomotor

137
Q
  • alternate eye focusing on objects due to weak extrinsic muscle
  • Treated by patching the strong eye to force weaker eye muscles to get stronger
A

Strabismus

WHAT UP

138
Q

Three layers of eyeball

A

Fibrous
Vascular
Sensory

139
Q

Internal cavity filled with fluids called

A

Humors

Aqueous and Vitrous

140
Q

This separates the internal cavity into anterior and posterior segments

A

Lens

141
Q

Outer Layer

A

Fibrous

142
Q

composed of two dense avascular connective tissue regions

A

Fibrous Layer

143
Q

Sclera and Cornea

A

Two Fibrous Layers of Eye

144
Q

white, opaque, tough layer

A

Sclera

145
Q

Protects and shapes the eyeball; anchors extrinsic muscles

A

Sclera

146
Q

At the optic nerve, ___ is continuous with the dura mater

A

Sclera

147
Q

transparent; anterior 1/6 of fibrous layer

A

Cornea

148
Q

bends light as it enters the eye

A

Cornea

149
Q

Numerous pain receptors contribute to blinking and tear reflexes

A

Cornea

150
Q

Covers the iris and pupil

A

Cornea

151
Q

Covered by the vascular conjunctiva

A

Sclera

152
Q

fastest healing tissue in the body

A

Cornea

153
Q

Gets O2 directly from the air

-Abrasions typically heal in 24-36 hours

A

Cornea

154
Q

middle layer, pigmented

A

Vascular Layer (Uvea)

155
Q

Has 3 regions: Choroid, Ciliary Body, Iris

A

Vascular Layer (Uvea)

156
Q

Posterior portion of the uvea

A

Choroid region

157
Q

Supplies blood to all eye layers of the eyeball

A

Choroid region

158
Q

Contains brown pigment that absorbs light to prevent visual confusion that forms the
posterior portion of the uvea

A

Choroid region

159
Q

A thickened ring of tissue surrounding the lens

A

Ciliary Body

160
Q

Composed of smooth muscle bundles (ciliary muscles) that control lens shape

A

Ciliary Body

161
Q

Anchors the suspensory ligaments that holds the lens in place (text: ciliary zonule)

A

Ciliary Body

162
Q

Ciliary processes contain capillaries that secrete fluid which forms the aqueous humor

A

Ciliary Body

163
Q

Pigmented portion of the anterior eyeball (Brown is the only pigment)

A

Iris

164
Q

central opening of the iris that regulates the amount of light entering the eye via
two different muscles

A

Pupil

Iris

165
Q

Close vision & bright light –muscles contract; pupils constrict
Parasympathetic Control

A

sphincter pupillae

Iris

166
Q

Distant vision & dim light –muscles contract; pupils dilate
Sympathetic Control

A

dilator pupillae

Iris

167
Q

Changes in emotional state affect the muscles -

- pupils dilate when object is appealing or requires problem-solving skills

A

pleasing

168
Q

Constrict/dilate when negative or lying

A

Constrict

169
Q

is the innermost layer composed of a delicate two-layered membrane

  • Pigmented
  • Neural
A

Retina

Sensory Layer

170
Q

Outer layer that absorbs light and prevents its scattering;

-stores Vitamin A

A

Pigmented

Retina

171
Q

melanin granules

A

Pigmented Layer

172
Q

Inner layer that covers the eyeball up to the ora serrata (where it joins the ciliary body)

A

Neural layer

173
Q

where eyeball joints ciliary body

A

ora serrata

174
Q

transmit signals and generate action potentials

A

Bipolar cells
-Ganglion cells
Neural Layer
Retina

175
Q

Its axons run along the inner surface of the retina

A

Ganglion cell

176
Q

This layer has Photoreceptors that transduce light energy

A

Neural Layers of Retina

177
Q

Connect the photoreceptors to the ganglion cells

A

bipolar cells

178
Q
  • run along the inner surface of the retina

- Axons are bundled and leave the eye as the optic nerve

A

Ganglion cell axons

179
Q
  • Site where the optic nerve leaves the eye

- No photoreceptors, so no signal to the brain

A

Optic disc (blind spot)

180
Q

Site where the optic nerve leaves the eye is the

A

optic disc

181
Q

No photoreceptors at optic disc, so this creates the

A

blind spot

182
Q

Approximately 250 million per eye

A

Photoreceptors

183
Q

More numerous at peripheral region of retina

A

Rods

184
Q

Operate in dim light;

provide indistinct, fuzzy, gray-scale peripheral vision

A

Rods

185
Q

Found in the macula lutea

concentrated in the fovea centralis

A

Cones

186
Q

Lens adjustments are made to get the focus of an object to land here

A

fovea

187
Q

Respond to bright light and provide high-acuity color vision

A

Cones

188
Q

blood vessels supplies the outer third of the retina (photoreceptors)

A

choroid

189
Q

Branches from the central artery & vein of the retina supply inner two-thirds (bipolar and
ganglion cells) of blood
-Enter/exit from the center of the ___ nerve
- Vessels branch from the optic disc and can be seen with an ____

A

optic

opthalmoscope

190
Q

Damage to the retinal blood vessels secondary to diabetes mellitus

A

Diabetic retinopathy

191
Q

Damage to the central visual field with detachment of the retina

A

Macular Degeneration

192
Q

“yellow body”

A

macula lutea

193
Q

The ___ & ___ ___ divide the internal eye into anterior & posterior segments

A

lens

suspensory ligaments

194
Q

anterior segment contains

A

aqueous humor

195
Q

posterior segment contains

A

vitreous humor

196
Q

(clear gel – looks like egg white); formed embryonically

A

vitreous humor

197
Q

Transmits light

A

vitreous humor

198
Q

Supports the posterior surface of the lens

A

vitreous humor

199
Q

Holds the neural retina firmly against the pigmented layer

A

vitreous humor

200
Q

Contributes to intraocular pressure

A

vitreous humor

201
Q

Has 2 chambers

  • anterior chamber
  • posterior chamber
A

Anterior Segment,

202
Q

Chamber between the cornea and the iris

A

Anterior chamber

Anterior segment

203
Q

Chamber between the iris and the lens

A

Posterior chamber

Anterior segment

204
Q

contains aqueous humor

A

anterior segment

205
Q

plasma-like fluid continuously filtered from capillaries of the ciliary processes

A

aqueous humor

anterior segment

206
Q

Drains continuously via the scleral venous sinus (canal of Schlemm) at the
sclera-cornea junction

A

aqueous humor

207
Q

Supplies nutrients & oxygen to and removes wastes from the lens and cornea
-Also supplies the retina via diffusion through the vitreous humor

A

Aqueous Humor

208
Q

Abnormal increase in intraocular pressure

A

Glaucoma

209
Q

Due to blocked drainager of the aqueous humor

A

Glaucoma

210
Q

If untreated, leads to an increase in intraocular pressure which causes retina and optic nerve damage

A

Glaucoma

211
Q

Treatment: eye drops with anti-inflammatory

A

Glaucoma

212
Q

A biconvex, transparent, flexible and avascular structure encased in an elastic capsule

A

Lens

213
Q

Can change shape to allow precise focusing of light onto the retina/fovea

A

Lens

214
Q

Composed of epithelium and lens fibers

A

Lens

215
Q

-anterior cuboidal cells;

differentiate into lens fibers throughout life

A

Lens Epithelium

216
Q

cells filled with the transparent proteins known as crystallins

A

Lens fiber

217
Q

With age, the lens becomes more compact and dense and loses/gains its elasticity

A

loses

218
Q

Loses the ability to recoil to a round shape, thus loss of close vision =

A

=presbyopia

219
Q

occur as a consequence of aging, diabetes mellitus, heavy smoking and frequent exposure to intense sunlight

A

=Cataracts

clouding of lens

220
Q

transparent proteins

A

crystallins

221
Q

packets of light that travel in a wavelike fashion)

A

=photons

Light

222
Q

visible spectrum

the small portion of electromagnetic spectrum

A

400-700 nm

223
Q

Different ___ in the retina respond to different wavelengths (blue, green, red)

A

cones

224
Q

___ only have one type of visual pigment, so everything is perceived in gray tones

A

Rods

225
Q

When light passes from one transparent medium to another at an oblique angle, it changes speed and bends =

A

Refraction

226
Q

when a convex lens forms an image, the image is ___ and ___ right to left

A

image is upside down and reversed right to left

227
Q

cornea, aqueous humor, lens, vitreous humor and neural layer of the retina to the photoreceptors

A

Pathway of light entering the eye

228
Q

Refraction Goal

A

Get the image to the fovea centralis

229
Q

Eyeball too short

Focal Pt?

A

Far Sighted
Behind retina
Hyperopic

230
Q

process by which the eye detects light energy

A

Photoreception

231
Q

what do rods and cones contain? what do they do as they absorb light?

A

Visual pigments which change shape

232
Q

Arranged in stacks of ___which are embedded in the pigmented layer of the retina

A

discs

rods and cones

233
Q

Sensitive to dim light and best suited for night vision and peripheral vision

A

Rods: Functional Characteristics

234
Q

Perceived input is in gray tones only

A

Rods: Functional Characteristics

235
Q

Sum of visual input from many rods feeds into a single ganglion cell & pathways
converge, resulting in fuzzy and indistinct images

A

Rods: Functional Characteristics

236
Q

Need bright light for activation

A

Cones: Functional Characteristics

237
Q

Have one of three pigments that furnish a vividly colored view (blue, green, red)

A

Cones: Functional Characteristics

238
Q

Congenital lack of one or more pigments (X-linked)

A

Cones: Functional Characteristics

239
Q

Each cone synapses with a single ganglion cell, so non-converging, resulting in
detailed and high resolution images

A

Cones: Functional Characteristics

240
Q

The light-absorbing molecule that combines with one of four opsins (protein) to form visual pigments

A

Retinal

241
Q

Similar to and is synthesized from Vitamin A

A

Retinal

242
Q

Two isomers: cis- and trans- form

A

Retinal

243
Q

Conversion from one form to the other is the stimulus for a chain of enzyme reactions
leading to transmission of APs in the optic nerve

A

Retinal

244
Q

The visual pigment of rods is

A

Rhodopsin

245
Q

In the dark, rhodopsin is formed and accumulates

A

Dark Phase

246
Q

When light is absorbed, rhodopsin breaks down (changes form)

A

Light Phase

247
Q

Retinal and opsin separate

A

Bleaching of the pigment

Light Phase

248
Q

Retinal and opsin separate & ultimately

causes APs to be transmitted along the optic nerve

A

Stimulation of Photoreceptors

249
Q

Its visual pigments are formed by retinal + opsins forming blue green and red cones

A

Excitation of Cones

250
Q

are perceived by activation of more than one type of cone

A

Intermediate Colors

251
Q

is perceived by activation of all of the cones equally

A

White

252
Q

Occurs when moving from darkness into bright light

A

Light Adaptation

Photoreceptors

253
Q

Large amounts of rod pigments are broken down instantaneously, perceived by
visual cortex as

A

glare

254
Q

Pupils constrict/relax to decrease the amount of light hitting retina

A

constrict

255
Q

Dramatic decrease in retinal sensitivity; rod function ceases/increases; therefore, can’t see if
return to the dark

A

ceases

256
Q

cones and neurons adapt quickly; visual acuity is gained rapidly and improves over 5-10 minutes

A

Switching from rod to cone system

257
Q

Occurs when moving from bright light into darkness

A

Dark Adaptation

258
Q

Cones stop functioning in

A

low light

259
Q

Pupils dilate/contract to capture as much light as possible

A

dilate

260
Q

Rhodopsin will again accumulate/decompose in the dark and retinal sensitivity is restored within
20-30 minutes

A

accumulate

261
Q

Medial fibers of the optic nerve decussate at

A

optic chiasma

(cross to contralateral side

262
Q

Lateral fibers do/don’t decussate

A

DO NOT

project to ipsilateral side

263
Q

Most fibers of the optic tracts continue to the

A

Thalamus

264
Q

Some optic tract fibers end in midbrain

A

superior colliculi (initiating visual reflexes)

265
Q

Optic radiations travel from the thalamus to the

A

visual cortex in the occipital lobe

266
Q

A small subset of visual fibers from the blue cones contain ___ (circadian pigment)
which sets daily biorhythms (inhibit melatonin release from the pineal gland)

A

melanopsin;

267
Q

is achieved by both eyes (binocular vision) viewing the same image from slightly different angles and visual cortex fusion of the slightly different images

A

Depth Perception

268
Q

If only one eye is used, depth perception is lost and the observer must rely on learned clues

A

Truth

269
Q

Visual Processing…

Involves many regions of the brain

A

You Ready?

270
Q

-donut shaped rod receptive fields detect different light patterns on center or off-center
-distinguishes edges/movement
-cone receptive fields provide sharpness and color
Receptive fields of ganglion cells detect different light patterns

A

Retinal Processing

271
Q

-Relays information on movement;
-segregates the retinal axons in
preparation for depth perception;
-sharpens the contrast information received by the retina

A

Thalamic Processing

272
Q

Review:

Axons of Retinal Ganglion cells form the ___

A

optic nerve

273
Q

Review

The optic nerve fibers cross at the

A

optic chiasma

274
Q

Production of ___ from the pineal gland is inhibited by light hitting these cells containing melanopsin

A

melatonin

275
Q

Primary visual cortex processes basic dark/bright and contrast information

A

Cortical Processing

276
Q

Visual association areas process form, color, and movement

A

Cortical Processing

277
Q

Visual information then proceeds anteriorly to the:

A

Temporal lobe – processes identification of objects

Parietal cortex and postcentral gyrus – processes spatial location

► Med - Anatomy & Physiology (130 decks)

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