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Neuroendocrine I: Exam 3 > Visual Tracts > Flashcards

Visual Tracts Flashcards

1
Q

Functions of Retinal Pigmented Epithelium

A
  1. Absorbs scattered light to supplement choroid (b/c has some melanin granules)
  2. Forms part of blood-retina barrier (separating photoreceptors from choroid)
  3. Isomerizes all-trans retinal –> 11-cis retinal –> sends back to photoreceptors
  4. Phagocytosis & degradation of components/waste from photoreceptors
  5. Remove free radicals & secretes ATP, polypeptide growth factors & immunomodulatory factors
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2
Q

Function of the superior colliculus

A
  • Important in directing eye movements
  • Spatially directs head movements and visual reflexes
  • Retinal input bypasses the lateral geniculate nucleus and targets the brachium of the superior colliculus –> terminates retinotopically
  • Also receives spinotectal (somatosensory) and auditory inputs
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3
Q

Function of the pretectal/pretectum area

A
  • Important in pupillary light reflex
  • Nuclei located near the midbrain/forebrain junction that receives inputs from optic tracts, lateral geniculate nucleus and the suprachiasmatic nucleus
  • Responds to varying intensities of illuminance and unconscious behavioral responses (e.g. pupillary light reflex)
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4
Q

Associative visual agnosia

A
  • Infarction of LT occipital lobe + posterior corpus callosum (especially splenium) typically due to posterior cerebral artery damage
  • Disconnects the language area from the visual association cortex –> Pt cannot name or describe an object in visual field BUT can recognize and demonstrate its use
  • Pts may also be alexic (unable to read) and writing ability may be affected (agraphia)
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5
Q

Name the visual field deficit for lesion: RT optic nerve

A

Total vision loss in RT eye

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6
Q

Name the visual field deficit for lesion: Optic chiasm (midline)

A

Bitemporal hemianopsia (heteronymous defect)

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7
Q

Name the visual field deficit for lesion: RT optic tract

A

Contralateral (LT) homonymous hemianopia

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8
Q

Name the visual field deficit for lesion: RT temporal lobe (Meyer’s loop)

A

Superior LT homonymous quadrantanopia (pie in the sky disorder)

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9
Q

Name the visual field deficit for lesion: RT parietal lobe

A

Inferior LT homonymous quadrantanopia (pie in the floor disorder)

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10
Q

Name the visual field deficit for lesion: RT Geniculocalcarine tract

A

Contralateral (LT) homonymous hemianopia

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11
Q

Name the visual field deficit for lesion: Inferior bank of RT calcarine fissure

A

Superior LT homonymous quadrantanopia w/ macular sparing

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12
Q

Name the visual field deficit for lesion: Superior bank of RT calcarine fissure

A

Inferior LT homonymous quadrantanopia w/ macular sparing

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13
Q

Name the visual field deficit for lesion: Both banks of RT calcarine fissure

A

Contralateral LT homonymous hemianopia w/ macular sparing

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14
Q

Describe the concentric tunics/layers that make up the eye

A
  1. Fibrous layer - tough external layer consisting of the sclera & cornea
  2. Vascular layer - choroid, ciliary body and iris
  3. Retina - inner sensory layer gives rise to optic nerve (layer II)
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15
Q

Sclera

A
  • Fibrous, external layer of eyeball which protects internal structures
  • Dense regular connective tissue w/ flat bundles of type I collage and microvasculature near outer surface
  • Extraocular muscles insert anteriorly on sclera
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16
Q

Cornea

A
  • Transparent and avascular structure w/ distinct layers (superficial to deep)
    1. Corneal epithelium - nonkeratinized stratified squamous
    2. Anterior limiting membrane (Bowman’s membrane)
    3. Thick stroma comprised of keratocytes
    4. Posterior limiting membrane (Descemet’s membrane) - basement membrane of endothelium
    5. Inner endothelium
17
Q

What is the limbus?

A
  • Transitional area where transparent cornea merges w/ opaque sclera
  • Denotes end of Bowman’s membrane and beginning of conjunctiva (covers the anterior sclera and lines the eyelids)
  • Epithelial stem cells at its surface give rise to progenitor cells that move into corneal epithelium
18
Q

Choroid

A
  • Consists of loose, well-vascularized connective tissue and contains numerous melanocytes
  • Black layer that prevents light from entering the eye from anywhere besides the pupil
19
Q

Ciliary body

A
  • includes ciliary muscle, processes & zonula

- Involved in affecting shape of lens (e.g. accomodation)

20
Q

Iris

A
  • Covers outer boundary of lens and creates the pupil

- Denotes color of our eyes

21
Q

Name the 9 layers of the neural retina (following path of light travel past the vitrous body)

A
  1. Inner limiting membrane - basement membrane covered by processes of Muller cells
  2. Nerve fiber layer (NFL) - contain ganglionic cell axons and converge @ optic disc to form CN II
  3. Ganglionic layer (GL) - contains ganglion cell bodies, thicker near retina’s center
  4. Inner plexiform layer (IPL) - contains fibers/synapses of ganglion cells and bipolar neurons
  5. Inner nuclear layer (INL) - bipolar cell bodies
  6. Outer plexiform layer (OPL) - contains fibers/synapses of bipolar neurons and rods/cones
  7. Outer nuclear layer (ONL) - cell bodies of rods/cones
  8. Outer limiting layer (OLL) - line of junctional complexes holding photoreceptors to Muller cells
  9. Rod and cone layer (RCL) - contains outer segments of rods/cones
22
Q

Fovea centralis

A
  • Highest concentration of cones
  • Area where visual acuity is sharpest (20/20)
  • Absence of blood vessels, cell bodies and axons of ganglionic & inner nuclear layer
23
Q

Macula Lutea

A
  • Surrounds fovea and protects cones

- Antioxidant properties and short wave UV filter

24
Q

Where does the LT half of visual field form an image on the retinas?

A
  • Nasal (RT) half of left retina

- Temporal (RT) half of right retina

25
Q

Where does the RT half of visual field form an image on the retinas?

A
  • Temporal (LT) half of left retina

- Nasal (LT) half of right retina

26
Q

Where does the inferior visual field information project in the primary visual cortex?

A

-Superior bank of the calcarine sulcus –> cuneus

27
Q

Where does the superior visual field information project in the primary visual cortex?

A

-Inferior bank of the calcarine sulcus –> lingual gyrus

28
Q

Where does the macula/fovea information project in the primary visual cortex?

A

-Represented more posteriorly in region of the occipital pole and peripheral fields more anteriorly

Neuroendocrine I: Exam 3 (18 decks)

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