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Neurology - Sem 3 > Case 3 - vision > Flashcards

Case 3 - vision Flashcards

1
Q

What does the individual model of disability say disability is caused by? (x3)

A
  1. Personal tragedy
  2. Medical problem
  3. Individual adjustment
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2
Q

what is the social model of disability? (x2)

A
  1. Disability is caused by societies views (Discrimination)
  2. Environment restricts life choices for disabled people
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3
Q

What does the medical model of disability say? (x2)

A
  1. People are disabled because of their impairments or differences
  2. These impairments can be fixed, medically. Allowing them to participate in society
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4
Q

Psychological model of disability? (x2)

A
  1. 2 people with identical conditions can have different activity limitations due to cognitions, emotions, and coping strategies
  2. People may also differ in their beliefs of their condition, so some may overcome their disability and others are defined by it
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5
Q

how is disability assessed?

A
  1. Using measures of activities of daily living (ADL) - looking at ability to perform everyday activites
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6
Q

What is stigma?

A
  • Negative evaluation and association of lowering respect for individuals because of personal characteristics
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7
Q

What is labelling theory?

What is primary and secondary deviance?

A
  • Social groups create deviance as they make rules which when broken = deviance. Actions are not deviant, it is societies reaction that makes it deviant.
  • Primary deviance = deviant acts before being labelled as deviant - perception unchanged
  • Secondary deviance = perception changes so public labels them as deviant. behaviour changes because of label of deviance
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8
Q

What are the 2 types of stigma?

A
  1. Enacted stigma = Societies reaction which leads to actual discrimination
  2. Felt stigma = Imagined social reaction which changes a persons self identity
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9
Q

What is sensation?

What are the 5 sensory modalities?

What is transduction?

A
  • Detection of stimuli which is registered by senses, leading to physiological or psychological response
  • Vision, audition, gustation, olfaction, somatosensation (body senses)
  • When sense organs convert energy from stimuli into neural activity
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10
Q
  • What is perception?
A
  • Interpretation of all sensory input
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11
Q

What are the 5 Gestalt principles?

A
  1. Adjacency/Proximity = object close are often grouped together
  2. Similarity = similar objects are perceived to belong together
  3. Good continuation = elements that smoothly follow a line tend to belong together
  4. Law of closure = Missing information is completed
  5. Common fate = elements with same movement trajectory belong together
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12
Q
  • What are templates?
  • What are Geons?
A
  • Visual memories of patterns compared with vision
  • Distinctive features, simple 3D shapes
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13
Q

Define the terms:

  • Wavelength
  • Frequency
  • Amplitude
  • Reflection
  • Refraction
  • Absorption
A
  • Distance between successive peaks and troughs
  • Number of waves per second
  • Difference between wave trough and peak
  • Light bounces off surface
  • Bending of light rays when travelling through different mediums (Air faster than water)
  • Transfer of light energy to surface, black absorbs all wavelengths (Visible)
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14
Q

Define the terms:

  • Reflection
  • Refraction
  • Absorption
A
  • Light bounces off surface
  • Bending of light rays when travelling through different mediums (Air faster than water)
  • Transfer of light energy to surface, black absorbs all wavelengths (Visible)
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15
Q

Label the diagram:

  • Refraction
  • Reflection
  • Absorption
A
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16
Q

Label the following on the eye:

  • Cornea
  • Pupil
  • Iris
  • Sclera
  • Conjunctiva
  • Optic nerve
  • Aqeuous humour
  • Vitreous Humour
  • Lens
  • Fovea
  • Anterior chamber
  • Posterior chamber
  • Ciliary body
  • Posterior cavity/Vitreous chamber
  • Optic disc
  • Retina
A
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17
Q

Define the following:

  • Focal distance - what does it depend on?
  • Diopter
  • What is the normal diopter of the eye?
  • Negative diopter
  • Positive diopter
A
  • Distance from light source to point where light rays converge. Depends on curvature of cornea
  • 1/F (Focal distance)
  • 42D
  • Focuses light before the retina, decreasing the focal distance
  • Focuses light after the retina, increasing the focal distance
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18
Q

Identify the following:

  • Convergence
  • Divergence
A
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19
Q
  1. What part of the eye is responsible for accomodation?
  2. What is required for objects that are close?
  3. Which muscles are responsible for accomodation?
A
  1. Lens
  2. Greater refractive power, to focus them on the retina
  3. Cilliary muscles
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20
Q
  1. What happens when the cilliary muscles contract?
  2. What happens when the cilliary muscles relax?
A
  1. Decreases tension on suspensory ligaments, makes lens thick & round
    1. Increased curvature = increased refractive power
  2. Increase tension on suspensory ligaments, makes lens flatter shape

Decrease curvature = decreased refractive power

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21
Q
  1. What is the function of the pupillary light reflex?
  2. What happens to the other eye when light is shone on one eye?
  3. Which nerve is responsible for the afferent pathway?
  4. Which nerve is responsible for the efferent pathway?
  5. Where do the axons from CN II go to?
  6. Where do the axons from the LGN synapse?
  7. Where do the efferent axons originate?
  8. Which muscles lead to the PLR?
A
  1. Allows the pupils to adjust for different ambient lighting lvels, also allows for better focus (Convergence)
  2. It also constricts - consensual reflex
  3. Optic nerve CN II
  4. Occulomotor nerve CN III
  5. Lateral Geniculate Nucleus, in the midbrain
  6. Pretectal nucleus
  7. Erdinger Westphal nucleus
  8. Constrictor pupillae muscles in the Iris
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22
Q
  1. Which muscles constrict the pupils?
  2. Which muscles dilate the pupils?
  3. What happens if the is incomplete damage to the afferent pathway?
A
  1. Pupillary sphincter muscle
  2. Radial muscles
  3. There will be slight dilation of the affected pupil
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23
Q

Identify what defect is present with each eye:

A
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24
Q
  1. What damage can lead to visual field problems? (x3)

What are the following defects?

  • Anopia
  • Homonymous Hemianopia
  • Heteronymous Hemianiopia
  • Binasal Hemianopia
  • Bitemporal Hemianopia
  • Quadrantanopia
A
  1. Retina damage, optic nerve damage or lesions, and damage to the occipital cortex
  • Visual field defect
  • Loss of half of visual field on the same side in both eyes
  • Loss of half of the visual field on different sides in both eyes
  • Loss of nasal field
  • Loss of temporal field
  • Decreased vision/blindness in 1/4 of the visual field
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25
Q

What does each defect show?

A

B

C

D

E

F

G

A
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26
Q

Define the following terms:

  1. Visual acuity
  2. Snellen chart - what is it for?
A
  1. Ability of the eye to distinguish 2 points near each other.
  2. Used to determine visual acuity, viewing letters from a distance of 6m/20ft
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27
Q
  1. What is the function of the retina?
  2. What are Bipolar cells?
  3. What are Horizontal cells? What is their input & what do they influence?
  4. What are Amacrine cells?
  5. What are ganglion cells?

Identify the cell types in the image:

A
  1. Converts light energy into neural activity
  2. They connect photoreceptors to ganglion cells
  3. Get input from photoreceptors, laterally influence bipolar cells & photoreceptors
  4. Input from bipolar cells and influence ganglion cells, bipolar cells, and other amacrine cells (Laterally)
  5. Only retinal neurons that fire AP, output from the retina to brain via optic nerve
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28
Q

Identify the layers of the retina:

  • Outer plexiform layer
  • Outer nuclear layer
  • Pigmented epithelium
  • Inner plexiform layer
  • Ganglion cell layer
  • Inner nuclear layer
  • Photoreceptors

What does each layer contain?

A
  • Outer plexiform layer - Photoreceptors synapse with BC & HC
  • Outer nuclear layer -Cell bodies of photoreceptors
  • Inner plexiform layer - Synaptic contacts of BC, HC, and AC
  • Ganglion cell layer - Ganglion cell bodies
  • Inner nuclear layer - Cell bodies of BC,HC, and AC
  • Pigmented epithelium
  • Photoreceptors - Outer segments of photoreceptors
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29
Q

Which of the following is the correct order of the layers of the retina:

A. INL, GCL, IPL, OPL, ONL, Photoreceptors, PE

B. PM, Photoreceptors, INL, IPL, ONL, OPL, GCL

C. ONL,OPL, INL, IPL, GCL, Photoreceptors, PE

D. PM, Photoreceptors, ONL, OPL, INL, IPL, GCL

A

D

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30
Q
  1. Which cells are responsible for light transduction?
  2. What are the 2 types of photoreceptors?
  3. What is the difference between rods and cones?
  4. When is each most active?
A
  1. Photoreceptors
  2. Rods & Cones
  3. Rods are responsible for night vision, Cones are responsible for day/colour vision
  4. Rods - Night, Cones - Day
31
Q
  1. Which cells can also act as photoreceptors?
  2. What photoreceptor can they use?
  3. What does light do to them?
  4. What is their use? (2)
A
  1. Intrinsically photoresensitive retinal ganglion cells (ipRGCs)
  2. Melanopsin
  3. Depolarise
  4. Circadian rhythms, and pupil responses
32
Q

Identify the following:

  • Rod cell
  • Cone cell
  • Outer segment
  • Inner segment
  • Synaptic terminal
  • Nucleus
  • Mitochondria
  • Cytoplasm
  • Membrane
  • Photopigment discs
33
Q

Identify:

  • Blind spot/Macula
  • Fovea
  • Rods - Which line?
  • Cones - which line?
34
Q
  1. Where is the highest concentration of each in the eye?
  2. What are the photopigments for each?
  3. What is the fovea?
  4. What is the blind spot?
A
  1. Rods - Peripheral retina, Cones - Fovea (Central)
  2. Rods - Retinal, Cones - Opsin
  3. Depression in the eye, where there is the highest concentration of cone cells
  4. Where no photoreceptors can be found, point where CN II exits the eye
35
Q
  1. What type of receptor do the photoreceptors use?
  2. What is the membrane potential of the rod outer segment?
  3. What is this called?
A
  1. G protein coupled receptor
  2. -30mV - Depolarised
  3. Dark current
36
Q
  1. What happens during the dark current?
  2. What enzyme produces cGMP?
  3. What NT is released?
A
  1. Na+ channes are stimulated to open by cGMP
  2. Guanylyl cyclase
  3. more Glutamate is released
37
Q
  1. What does light do to the rods?
  2. What happens to the membrane potential?
  3. What happens to the NT release?
A
  1. Reduction in cGMP leads to Na+ channels closing
  2. More negative membrane potential (Hyperpolarises)
  3. Less glutamate is released
38
Q
  1. What is the photopigment in the rod cells?
  2. What happens to it when light is absorbed?
  3. What does Rhodopsin do to the photoreceptor?
  4. What is the end result?
A
  1. Rhodopsin
  2. Conofrmational change of retinal to activate opsin (Bleached)
  3. Rhodopsin stimulates transducin which activates PDE
  4. This breaks down cGMP in the cytoplasm
39
Q
  1. What is the pathway for retinal production from vitamin A?
  2. What is the receptor it is bound to?
  3. When and why do rods become saturared?
A
  1. Trans retinol (Vitamin A) — 11 Cis retinal — trans retinaldehyde
  2. Opsin
  3. When we are in bright light, because the cGMP levels are so low. Increasing light levels cause no additionally hyperpolarisation
40
Q
  1. What photopigment do cones contain?
  2. What happens to the rod cells in light?
A
  1. 3 different types of opsin with different spectral sensitivities (R,G,B)
  2. Dark current is shut off
41
Q
  1. Which colour of light has the shortest wavelength?
  2. Which colour of light has a medium wavelength?
  3. Which colour of light has a long wavelength?
A
  1. Blue
  2. Green
  3. Red
42
Q
  1. What physiological mechanism helps regenerate rhodopsin when photoreceptors are bleached?
  2. What also flows into the photoreceptors and inhibits Guanylyl cyclase?
  3. How is rhodopsin regenerated?
  4. What is this used to reverse?
A
  1. Constriction of the pupil
  2. Ca+
  3. Flow of Ca+ is stopped when the Na+ channels are closed, so inhibition is stopped more cGMP produced
  4. Saturation
43
Q
  1. Which cells fire AP’s in the retina?
  2. What is the simple pathway from the photoreceptor to the neuron?
  3. What cells modify the responses to light?
A
  1. Ganglion cell
  2. Cone/Rod cell — Bipolar cell – Ganglion cell
  3. Amacrine, and horizontal cells
44
Q
  1. What is the receptive field?
  2. What are the 2 components to the receptive field?
  3. Which 2 cells can have receptive fields?
A
  1. Area of retina where if light is shone on it, the firing rate of the neurons will change
  2. Receptive field surround & Receptive field center
  3. Ganglion cells & Bipolar cells, these respond to defined stimuli
45
Q
  1. What are the 2 ways bipolar cells can be connected to photoreceptors?
  2. What are the 2 classes of bipolar cells?
A
  1. Directly, and Indirect (Horizontal cells modulating)
  2. ON & OFF
46
Q
  1. What is an ON bipolar cell?
  2. What type of receptors are these?
  3. What is the overall effect on these?
A
  1. Light shone on these depolarises them (ON)
  2. Metabotropic - G protein glutamate receptor
  3. Glutamate makes them depolarise
47
Q
  1. What are OFF bipolar cells?
  2. What type of glutamate receptors are they?
  3. What is their overall effect?
A
  1. Light shone on these hyperpolarises them (OFF)
  2. Ionotropic
  3. Less NT is released (Glutamate)
48
Q
  1. What is the indirect connection for bipolar cells?
  2. What happens to the horizontal cells when there is light?
  3. What does this do to the central bipolar cell?
A
  1. They are connected via horizontal cells to a ring of photoreceptors that surround central cluster
  2. Photoreceptor hyperpolarises and out also causes horizontal cells to hyperpolarise
  3. It will also hyperpolarise
49
Q
  1. What is the receptive field center?
  2. What is the receptive field surround?
  3. Where do the receptive field bipolar cells synapse with ganglion cells?
A
  1. Circular area of retina providing direct photoreceptor input
  2. Surrounding area of retina, providing input via horizontal cells.
  3. Inner plexiform layer
50
Q
  1. Where do the ON & OFF cell ganglion cells receive their input?
  2. When do ganglion cells fire AP?
A
  1. Corresponding bipolar cells so, ON center bipolar cell goes to ON center ganglion cell
  2. ALL the time, stimulation simply increases or decreases firing
51
Q
  1. What does an ON center ganglion cell do?
  2. What does an OFF center ganglion cell do when there is light?
A
  1. Increase AP’s when a small spot of light is projected onto the center of its receptive field
  2. Decrease AP’s when a small spot of light is projected to the center of its receptive field. Prefers dark
52
Q
  1. What happens if the center and Surround are stimulated?
A
  1. The effect is cancelling so there will have a little increase in AP but not significant
53
Q
  1. What are the 3 types of ganglion cells, based on appearance?
  2. Which cells make up the larger number?
  3. Which are larger?
A
  1. M type type ganglion cells & P type type ganglion cells & NonM-NonP ganglion cells
  2. P type GC
  3. M type GC
54
Q
  1. What do M type GC’s have?
  2. What do P type GC have?
A
  1. Large receptive field, sensitive to low contrast stimuli
  2. Smaller receptive field, suited for discrimination of fine detail
55
Q
  1. Which cells are sensitive to differences in wavelength of light?
  2. What are they called?
  3. What are the 2 types of opponency?
A
  1. P type GC’s & Non-M Non-P GC’s
  2. Color opponent cells
  3. R v G & B v Y
56
Q
  1. What happens with a cell with a Red ON center v Green OFF surround? When:
  • Red light shone on center
  • Red light over both center and surround
  • Green light on surround
  • White light on receptive field
A
  • Increase in AP’s
  • Excited so slight increase in AP’s (Activation of green = inhibition)
  • Full inhibition, cancels the red ON center
  • both center and surround = activated, no response to light
57
Q
  1. Where does the primary visual pathway project to?
  2. What are the 3 other visual pathways? What are they used for?
A
  1. Lateral Geniculate nucleus
  2. Superior colliculus (Eye movement), Hypothalamus (Circadian rhythm), and Pretectum (Pupillary light reflex)
58
Q
  1. What is the path for the neurons from the eyes?
  2. Which axons decussate at the optic chiasm?
A
  1. Ganglion cells axons via optic nerve — Optic chiasm — Optic tracts
  2. Nasal retinal axons
59
Q
  1. What are the 2 main visual fields?
  2. Which side of the brain is the right visual hemifield visualised?
A
  1. Temporal & Nasal
  2. Left side of the brain
60
Q
  1. Where do the axons of the optic tracts synapse? (3)
  2. Where is the lateral geniculate nucleus found?
A
  1. Hypothalamus, Midbrain, and Majority - Lateral Geniculate nucleus
  2. Dorsal thalamus
61
Q
  1. What do the axons from the LGN give rise to?
  2. Where do they project to?
A
  1. Optic radiation
  2. Primary visual cortex (Occipital lobe)
62
Q
  1. What do the projections to the thalamus do?
  2. What do the projections to the pretectum do?
  3. Where is the pretectum?
A
  1. Necessarily for sleep and the dark light cycle
  2. Control the size of the pupils
  3. Midbrain
63
Q
  1. Which visual field does the R LGN receive input from?
  2. Where do the ipsilateral axons synapse in the LGN?
  3. Where do the Contralateral axons synapse in the LGN?
A
  1. Left visual field (R temporal retina & L nasal retina)
  2. Ipsilateral axons synapse in LGN layers 2,3,5
  3. Contralateral axons synapse in LGN layers 1,4,6
64
Q
  1. Where are the larger neurons found in the LGN?
  2. What cells are found in each layer?
  3. What is the last layer ventral to the main cells? What cells are found here?
A
  1. Layers 1 & 2, rest are small
  2. Layers 1&2 — Magnocellular LGN layers, Layers 3-6 — Parvocellular LGN layers
  3. K1 layer (Konicellular LGN layers) - Contain nonM nonP type ganglion cells
65
Q
  1. Which ganglion cells project to each layer?
  2. Where does the LGN then project to?
A
  1. M type — Magnocellular layer, P type — Parvocellular layer
  2. Primary visual cortex
66
Q
  1. What is perception based on?
  2. Which layer of the cortex receives the visual axons?
A
  1. Brains interpretation of distributed patterns of activity
  2. Layer IV
67
Q
  1. What is the dorsal stream?
  2. What is the ventral stream?
A
  1. From visual cortex to parietal lobe, used for analysis of motion and visual control of action
  2. From the visual cortex to the temporal lobe, used for perception of the visual world and recognition of objects
68
Q
  1. What is the pathway of the pupillary light reflex?
  2. Where does the afferent pathway go to?
  3. Where does the efferent pathway begin?
A
  1. Ganglion cell — Superior colliculus & Pretectal nucleus — Erdinger westphal nucleus — Occulomotor nerve — constriction of pupils
  2. Superior colliculus
  3. Erdinger Westphal nucleus
69
Q

Define the following:

  • Hyperopia
  • Myopia
A
  • Eyeball too short, not enough accomodation so light is focused behind the retina
  • Eyeball too long, too much accomodation so light is focused in front of the retina
70
Q

Define:

  • Astigmatism
  • Presbyopia
  • Glaucoma
A
  • Irregularities in curvature and refraction in different planes
  • Hardening of crystaline lens in old age, less elastic so difficult to accomodate
  • Pressure buildup in eye, so axons get damaged
71
Q
  1. What lens is used to treat hyperopia?
  2. What lens is used to treat myopia?
  3. What lens is used to treat astigmatism?
A
  1. Convex lens (Curved) increased refraction - Negative lens
  2. Concave lens (Flatter) decreased refraction - Positive lens
  3. Cylindrical or spherical lens
72
Q
  1. What is keratoconus?
  2. What is ambylopia?
A
  1. Degenerative change in retina causing it the become conical
  2. Functional reduction in visual acuity caused by disuse of eye during visual development
73
Q
  1. What is diplopia?
  2. What is strabismus?
A
  1. Double vision
  2. Imbalance in extra-occular muscles of two eyes, so point in different directions
74
Q
  1. What are the 2 types of strabismus?
  2. What is esotopia?
  3. What is exotopia?
  4. Treatment?
A
  1. Esotopia & Exotopia
  2. Convergent squint, cross eyed
  3. Divergent squint, wall eyed
  4. Prismatic glasses or surgery

Neurology - Sem 3 (15 decks)

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