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Yr2 Control - Term 2 and 3 > Visual Pathway > Flashcards

Flashcards in Visual Pathway Deck (67)
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1

Which part of the eye contains no photoreceptors?

The optic disc.
-blind spot on retina

2

Where is the optic disc located?

On the retina, medial to the fovea.

3

What is the retina?

The nerve layer that lines the back of the eye, senses light, and creates impulses that travel through the optic nerve.

4

What are the 2 layers of the retina?

-Non-neuronal layer
-Neuronal layer

5

What does the non-neuronal layer of the retina consist of?

Pigmented epithelium.
-sits against the choroid of the eyeball and absorbs photons

6

What are photons?

Particles of light energy.

7

What is the function of the pigmented epithelium?

Surrounds photoreceptors via melanin-filled microvilli.
-maintains their metabolic activity

8

What does the neuronal layer of the retina contain? (4)

-Photoreceptors
-Bipolar neurons
-Ganglionic cells
-Interneurons

9

What do photoreceptors do?

Receive photons and convert them into signals.

10

What are the 2 types of photoreceptors?

-Cone cells
-Rod cells

11

Why does light have to pass through other fibres to get to photoreceptors?

Decreases the intensity of light reaching the retina.

12

What do bipolar neurons do?

Connect photoreceptors to ganglionic cells.

13

What do ganglionic cells combine to form as they leave the retina?

The optic (II) nerve.

14

What is the function of interneurons?

Interconnect photoreceptors/bipolar neurons/ganglionic cells.
-modulate transmission and sharpen information to the cortex

15

What are the 2 types of interneuron?

-Horizontal
-Amacrine

16

Where are horizontal interneurons located?

At the level of photoreceptors and bipolar neurons.

17

Where are amacrine interneurons located?

At the level of bipolar neurons and ganglionic cells.

18

What process occurs in the neuronal layer of the retina?

Photochemical reactions tranduce photons (light energy) to electrical energy.

19

How many neurons are there from the retina to the cortex?

Three.

20

What is the pathway of light energy from the retina to the cortex?

Photoreceptors
>> 1* BIPOLAR CELLS
>> 2* GANGLIONIC CELLS
>>Optic nerve
>> Lateral geniculate nucleus (thalamus)
>> 3* OPTIC RADIATION
>> 1* visual cortex (cerebral cortex)
>> Association centre

21

What is the optic nerve an outgrowth of?

The diencephlon.
-part of the CNS

22

What membranes surround the eyeballs?

Meninges.

23

What effect can increased CSF/ICP have on vision?

Can cause the optic nerve to swell and compress the retinal central vein >> PAPILLOEDEMA.
-lifts retina away from the pigmented epithelium

24

What is papilloedema?

Optic disc swelling due to increased ICP.
>> headache, drowsiness, blurred vision

25

Which part of the thalamus does the visual pathway go to?

Lateral geniculate nucleus.

26

NB. Which part of the thalamus does the auditory pathway go to?

Medial geniculate nucleus.

27

Where does vision from the same area of the visual field travel?

Enters different eyes, but travels down the same optic tracts.

28

Where does the medial (nasal) retina send information to?

The contralateral thalamus.

29

Where does the lateral (temporal) retina send information to?

The ipsilateral thalamus.

30

Where does information from the medial retina cross over?

At the optic chiasma >> contralateral lateral geniculate nuclei.