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Neurology > Vision System > Flashcards

Vision System Flashcards

1
Q

Half of the total brain mass is devoted to visual processing

A

holy shit

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2
Q

Occipital cortex serves what function

A

Perception

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3
Q

Visual memories stored where?

A

Parietal and Temporal Lobes

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4
Q

Visual reflex

A

Brainstem and spinal cord

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5
Q

Visual system provides information required for setting of the circadian rhythms, general metabolic rate, mood, etc…

A

These parts of vision occur in the pineal gland (circadian rhythm) and diencephalon

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6
Q

HTN often diagnosed through analyses of the retina before blood pressure changes are noted by the patient

A

ok

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7
Q

Functions of the sympathetic nervous system can be tested by pupil dilation

A

ok

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8
Q

Fine focusing of incoming light is accomplished by

A

Fovea which is at teh center of the macula of the eye. Many animals do not have a macula or a fovea which is why their vision is not as crisp as ours.

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9
Q

Lens refraction abilitites are controlled by

A

Cilliary muscles that are under sympathetic and parasympathetic nervous system control

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10
Q

What is the sclera

A

a protective layer for the retina and choroid

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11
Q

What is the choroid

A

The vascular bed of the outer retina

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12
Q

Retinal blood flow is provided by

A
  • Central Retinal Artery that enters through the optic nerves and supplies about 20% of the blood in the human retina.
  • Choroid supplies the vast majority of blood to the retina
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13
Q

Fovea is devoid of vessels

A

If vessels grow there it distorts the image

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14
Q

Pigment cells in the retina are called what and serve what purpose

A

Retinal Pigmented Epithelial cells. They provide a barrier to the Retina from the choroid

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15
Q

Photoreceptor cell bodies lie where

A

outer nuclear layer, their projections lie in the outer plexiform layer

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16
Q

Retinal pathway

A

Photoreceptors (rods and cones) -> bipolar cells -> to ganglion cells

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17
Q

What is the purpose of interneurons

A

They help in convergence of the image from the millions of photoreceptors to hundreds of bipolar cells to tens of ganglion cells.

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18
Q

Interneurons located where

A

Outer plexiform layer (horizontal cells)

Inner plexiform layer (amacrines)

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19
Q

Ganglion cell axons coalesce to do what

A

Form optic nerve head.

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20
Q

Where is the blind spot

A

Optic nerve entry into the retina

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21
Q

RPE main function

A

separate vascular choroid from neural retina

22
Q

Macular degeneration results when….

A

blood vessels damage the RPE and break through their barrier to the macular region of the eye. This causes visual distortion of the image

23
Q

What is the other main function of the RPE

A

To eat outer rod segments every 10 days. As we age, this becomes less effective. Proteins are left in the RPE and they can autoflouresce. This is called Drusen which is a key factor of macular degeneration

24
Q

Melanin in the RPE does what

A

absorbs some of the light that comes to the photoreceptors

25
Q

Rods are responsible for

A

black and white vision

26
Q

Light transduction occurs in what segment of rods

A

outer segment

27
Q

KNOW that the outermost outer segment of rods is phagocytosed by the RPE cell layer every 10 days. A new outer segment extends from the inner segment and joins up with the other segments.

A

ok

28
Q

Cones are responsible for

A

color vision

29
Q

3 types of cones

A

L- long wavelenghts
M- Medium wavelengths
S- Shorter wavelengths

30
Q

M and L cones are carried on what chromosome

A

X…thats why men are more likely to be colorblind, because they have only 1 x chromosome.

31
Q

L cones

A

red

32
Q

M cones

A

green

33
Q

S cones

A

blue

34
Q

Vision occurs when rods and cones…….. to light

A

hyperpolarize!!! This is the only sensory system where hyperpolarization is the key response to light

35
Q

KNOW slide 15

A

ok…Most important slide of presentation

36
Q

Once photoreceptors have processed the light, signal is passed to what

A

Bipolar cels

37
Q

Rod Photoreceptors transduce their signal to rod bipolar cells and cone photoreceptors transduce their signal to

A

Cone bipolar cells

38
Q

What cell types help to converge the signal from a bunch of rod photoreceptors to fewer rod bipolar cells

A

horizontal cells

39
Q

Ganglion cells

A

There are different types. They activate based on image and project to different regions of the brain

40
Q

Alpha ganglion cells

A

Most from rods.Teir job is to help locate the object in space. Project to magnocellular layer of LGN

41
Q

Beta ganglion cells

A

Found Primarily in central retina. Define color and texture. Respond predominantly to cones. Project to Parvocellular region of LAG

42
Q

What alows for crisp image representation

A

in teh fovea there is 1 photoreceptor/1 ganglion cell

NO CONVERGENCE!!!

43
Q

Left visual field is processed where

A

Right visual cortex

44
Q

So we know that images are inverted and shrunk once they cross through the eye. What is it about the eye that causes the image to shrink

A

Refracted by the LENS and CORNEA

45
Q

Lens refraction is under control of what?

A

Ciliary muscles

46
Q

Note that convergence does not occur in the fovea!!! One photoreceptor supplies one ganglion cell

A

This is why the image is crisp.

47
Q

WHich fibers cross in the optic chiasm

A

only the nasal fibers

48
Q

Once passing through the optic chiasm, where do fibers move?

A

Into the Lateral Geniculate ganglion and into the visual cortex

49
Q

Diabetic retinopathy

A

changes in vasculature (GF)

Changes in

50
Q

Dry macular degen vs wet

A

Dry: LIttle vision loss in one eye usually. 90% of cases

Wet: blood vessels grow into macula and cause significant visual loss…both eyes

Neurology (38 decks)

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