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Flashcards in The Visual System Deck (82)
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1

how does light affect our perception

wavelength and intensity of a light affects COLOUR and BRIGHTNESS

2

iris

donut shaped bands of contraticle tissue that affect the amount of light entering the retina

3

pupil

hole in lens where light enters which adjusts in size to changes in light (sensitivity and acuity)

4

lens

focuses light on retina; adjusted by cillary muscles

5

sensitivity

ability to detect presence of an object in dim light

6

actuity

abilitiy to see details of an object

7

accomodation

adjusting configuration of lenses to bring images into focus on the retina

8

label an eye diagram

x

9

what have verebrates evolved to have

bilateral vision
stereoscopic vision (3D perspection)
bincoular disparity
colour vision

10

convergence

eyes coordinate so poitns in visual world correspond to the retina

11

binocular disparity

difference in position of the same image on 2 retinas

12

label the cells in the retina

x

13

amacrine and horizontal cells

specialized for lateral communication

14

fovea

indentation of ceter of retina for 'high acuity' vision
this thin layer dilutes incoming light

15

blind spot

where optic nerve connects= hence no visual processining occurs here

16

how does the visual system cope with the blindspot

visual information by periperhal receports fill in the 'gaps' (completion)

17

types of photoreceports

rods and cons

18

cones

phototrophicv vision
colour perecpetion
high lighting
high actuity
1 cone to 1 bipolar cell
3 types (RGB)
in centre of the retina
few cones converege to each ganglion cell

19

rods

scotopic vision
sensitive vision (shape/detail, etc)
dim lighting
low acuity
several rods converge to 1 ganglion cell (multiple rods: 1 bipolar cell)
1 type
peripheray of retina

20

visual perception

summation of recent visual information

21

temporal integration

how visual system fills in time-lags during processes

22

involuntary fixational eye movement

eyes are contionusly moving to allow us to see even duraction fixation

this results in tremors, drifts and saccades

23

visual transduction

conversion of one form of energy to another: in terms of visual transduction this referes to the conversion of light to neural signals

24

how does visual transduction occur

rhodopsin absorbs light in visual receptors; this is a G-Protein that responds to LIGHT instead of neurotransmitters which activates chemical events

it acts by INHIBITION

25

in dark light, rhodopsin... (3 steps)

1. rhodopsin is inactive
2. sodium channels open
3. sodium ions flow into rods= slight depolarization of them

26

in bright light, rhodopsin... (3 steps)

1, light reaches rhodopsin
2. sodium channels close
3. sodium ions can't enter= hyperpolarizes rods

27

after passing through the retina, what happens to visual information

it is transported vis the retina-geliculate striate pathways to the primary visual cortex

signals from LEFT visual field are transported to RIGHT primary visual cortex

28

retina reliculate striate pathways mechansims

carry signals from retina to primary visual cortex via the lateral geniculai nuclei in the thalamus using left and right pathways

29

RGS pathways

6 layers; each layer of each nucleus has different input from all the convulaed visual fields on an eye

30

retinotopic organization

RGS is retinotopic as each level is organized as a map in the retina

disproportionate amount of each system is dedicaed to analyzing the fovea