Vision System Flashcards Preview

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Flashcards in Vision System Deck (50):
1

Half of the total brain mass is devoted to visual processing

holy shit

2

Occipital cortex serves what function

Perception

3

Visual memories stored where?

Parietal and Temporal Lobes

4

Visual reflex

Brainstem and spinal cord

5

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

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

6

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

ok

7

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

ok

8

Fine focusing of incoming light is accomplished by

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.

9

Lens refraction abilitites are controlled by

Cilliary muscles that are under sympathetic and parasympathetic nervous system control

10

What is the sclera

a protective layer for the retina and choroid

11

What is the choroid

The vascular bed of the outer retina

12

Retinal blood flow is provided by

- 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

13

Fovea is devoid of vessels

If vessels grow there it distorts the image

14

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

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

15

Photoreceptor cell bodies lie where

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

16

Retinal pathway

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

17

What is the purpose of interneurons

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

18

Interneurons located where

Outer plexiform layer (horizontal cells)
Inner plexiform layer (amacrines)

19

Ganglion cell axons coalesce to do what

Form optic nerve head.

20

Where is the blind spot

Optic nerve entry into the retina

21

RPE main function

separate vascular choroid from neural retina

22

Macular degeneration results when....

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

What is the other main function of the RPE

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

Melanin in the RPE does what

absorbs some of the light that comes to the photoreceptors

25

Rods are responsible for

black and white vision

26

Light transduction occurs in what segment of rods

outer segment

27

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.

ok

28

Cones are responsible for

color vision

29

3 types of cones

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

30

M and L cones are carried on what chromosome

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

31

L cones

red

32

M cones

green

33

S cones

blue

34

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

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

35

KNOW slide 15

ok...Most important slide of presentation

36

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

Bipolar cels

37

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

Cone bipolar cells

38

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

horizontal cells

39

Ganglion cells

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

40

Alpha ganglion cells

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

41

Beta ganglion cells

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

42

What alows for crisp image representation

in teh fovea there is 1 photoreceptor/1 ganglion cell

NO CONVERGENCE!!!

43

Left visual field is processed where

Right visual cortex

44

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

Refracted by the LENS and CORNEA

45

Lens refraction is under control of what?

Ciliary muscles

46

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

This is why the image is crisp.

47

WHich fibers cross in the optic chiasm

only the nasal fibers

48

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

Into the Lateral Geniculate ganglion and into the visual cortex

49

Diabetic retinopathy

changes in vasculature (GF)
Changes in

50

Dry macular degen vs wet

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

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