Physiology of vision Flashcards Preview

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Flashcards in Physiology of vision Deck (19):
1

Describe the pathway of light in the retina in terms of the cellular layers?

Ganglion cell
Bipolar cell
Photoreceptos

2

Describe the direction of signal in the retina in terms of cellular layers

Photoreceptors
Bipolar cells
Ganglion cells

3

In what light conditions will the glutamate release be at its highest?

Dark

4

What does light do to rhodopsin?

Converts 11-cis -retinal to all-trans retinal

5

Will light open or close sodium channels?

Closes them

6

Will light increase or decrease cGMP levels within the retina?

Decrease

7

Do rods show high or low convergence?

High (and therefore cones show low)

8

What is the impact of a higher convergence in the rod system?

Increased sensitivity whilst decreasing acuity

9

Describe the 3 different cones and the light they process

Short wave = blue
Medium wave = green
Long wave = red

10

Describe the OFF pathway in the retina

Dark = more glutamate
Ionotropic receptors on bipolar cells
Membrane is more positive
Ganglion cell is more positive; action potential

11

Describe the ON pathway in the retina

Light; less glutamate
Metabotropic receptors on bipolar cells resulting in decreased calcium and increased potassium
Membrane more positive
Ganglion cell more positive; action potential

12

What is the function of lateral inhibition?

Exaggerates the difference in stimulus intensity detected by adjacent neurones
Aids with localization

13

What neurotransmitter will horizontal cells release?

GABA

14

What is the center surround organisation in the retina?

Ganglion cells have an either an ON centre and OFF surround or OFF centre and ON surround

15

What is the purpose of the center surround organization?

Emphasize areas of contrast; i.e. it sharpens the boundary between objects of different luminance

16

What are the different types of retinal ganglion cells?

M - movement
P - form and colour

17

Which fibres from the eyes will decussate?

Nasal fibres at the optic chiasm

18

Which layer of the primary visual cortex is vision processed?

Layer 4C

19

What is the purpose of the cortical receptive fields?

Orientation selectivity
Responds to light and dark