7: Physiology - Vision Flashcards Preview

Neurology Week 2 2018/19 > 7: Physiology - Vision > Flashcards

Flashcards in 7: Physiology - Vision Deck (16)
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1

What is strange about the cell arrangement of the retina?

Light passes THROUGH ganglia to reach photoreceptors

'inside out' arrangement

2

Photoreceptors (depolarise / hyperpolarise) in response to light.

hyperpolarise

unusual

3

Photoreceptors (depolarise / hyperpolarise) in the dark.

depolarise

4

What neurotransmitter is released when photoreceptors depolarise in the dark?

Glutamate

5

Which protein is converted to retinol when photoreceptors are struck by light?

Rhodopsin

6

When photoreceptors hyperpolarise by being exposed to light, what neurotransmitter is released?

No neurotransmitter is released

Not depolarised

7

Why do photoreceptors hyperpolarise when struck by light?

Rhodopsin activates G proteins (transducins)

Which indirectly CLOSE Na+ channels (causing hyperpolarisation)

(By activating PDE, which breaks cGMP (which is keeping Na+ channels open) to GMP. Na+ channels close, stopping Na+ influx. K+ efflux continues. Hyperpolarisation)

8

Describe some characteristics of cone cells.

Responsible for colour vision

High acuity

Low sensitivity

Low convergence

Found at the fovea

9

Describe some characteristics of rod cells.

Low-light vision, B&W

Low acuity

High sensitivity

High convergence

10

What process, by which excited neurons inhibit the neurons around them, also occurs in the eye?

Lateral inhibition

11

What is the point of lateral inhibition?

Reduces the excitation of other neurons, 'drawing attention' to a specific sitmulus​

In the eyes: helps with localisation of specific stimuli

12

Lateral inhibition exaggerates the ___ between different stimuli.

contrast

13

What is

a) tonotopy

b) retinotopy?

a) Different frequencies of sound are processed by different areas of the auditory cortex in the temporal lobe

b) Visual information from different visual fields are processed by different areas of the visual cortex in the occipital lobe

14

Which anatomical feature divides the posterior occipital cortex into

a) superior and inferior

b) left and right

sections?

a) Calcarine sulcus

b) Falx cerebri

15

Which nucleus do the optic tracts synapse at?

Lateral geniculate nucleus

16

The optic radiations plug in to which area of the brain?

Posterior occipital cortex

Visual cortex