physiology of light

Question 1

what is the pupil

Answer 1

opening where light enters the eye

Question 2

what is the sclera

Answer 2

white of the eye

Question 3

what is the iris

Answer 3

gives colour to the eye

Question 4

what is the cornea

Answer 4

glassy transparent external surface to the eye

Question 5

what is the optic nerve

Answer 5

bundle of axons from the retina

Question 6

when the eye collects light where does it focus to

Answer 6

the retina

Question 7

what is a unique feature about how the eye perceives images

Answer 7

it is inverted

Question 8

ERROS OF REFRACTION
what is emmetropic

Answer 8

normal eye

Question 9

ERRORS OF REFRACTION
what is presbyopia

Answer 9

as you get older the lens harden and the cilia muscles weakens, causing a decreased ability in accomodation

Question 10

what is hyperopia

Answer 10

far saightedness

Question 11

what is myopia

Answer 11

near sightedness

Question 12

in addition to the cornea and the lens, the pupil contributes to the optical functioning of the

Answer 12

eye

Question 13

PUPILLARY LIGHT REFLEX
the pupils continuously adjust to what

Answer 13

different light levels

Question 14

PUPILLARY LIGHT REFLEX
the pupils can be described as consensual
what does this mean

Answer 14

both pupils react similarly and simultaneously

Question 15

PUPILLARY LIGHT REFLEX
circular (constrictor) muscles act to _____ pupil size

Answer 15

decrease

Question 16

PUPILLARY LIGHT REFLEX
circular (constrictor) muscles act to decrease pupil size under what control

Answer 16

parasympathetic

Question 17

PUPILLARY LIGHT REFLEX
radial (dilator) muscles act to _____ pupil size

Answer 17

increase

Question 18

PUPILLAR LIGHT REFLEX
radial (dilator) muscles act to increase pupil size under what control

Answer 18

sympathetic

Question 19

what is the visual field

Answer 19

amount of space viewed by the retia when the eye is fixated straight ahead

Question 20

what is visual acuity

Answer 20

ability to distinguish two nearby points

Question 21

what is visual acuity determined by

Answer 21

largely by photoreceptor spacing and refractive power

Question 22

what cells are involved in the pathway for signal transmission and what order to they transmit in

Answer 22

photoreceptors -> bipolar cells -> ganglion cell s

Question 23

what do horizontal cells receive input from
and what do they project to

Answer 23

photoreceptors
photoreceptors and bipolar cells

Question 24

what do amacrine cells receive input from
and what do they project to

Answer 24

bipolar cells
project to ganglion cells, bipolar cells, and other amacrine cells

Question 25

what cranial nerve is the optic nerve

Answer 25

CNII

Question 26

what is transduction the converting of

Answer 26

converts electromagnetic radiation to neural signals

Question 27

what are the two types of photoreceptors

Answer 27

cones and rods

Question 28

what are the 4 main regions of a photoreceptor

Answer 28

outer segment inner segment cell body synaptic terminal

Question 29

light converts 11-cis retinal to what

Answer 29

all-trans retinal

Question 30

what enzyme converts all trans retinal back to 11-cis retinal

Answer 30

isomerase

Question 31

what is rhodopsin made of

Answer 31

opsin and 11 cis retinal

Question 32

MOLECULAR PATHWAY OF LIGHT What happens when all trans retinal activates transducin

Answer 32

decrease in cGMP

Question 33

MOLECULAR PATHWAY OF LIGHT what happens when there is decreased cGMP

Answer 33

closure of cGMP gated Na+ channels

Question 34

MOLECULAR PATHWAY OF LIGHT

Question 35

MOLECULAR PATHWAY OF LIGHT what happens whem there is the closure of cGMP-gated Na+ channel

Answer 35

lowered entry of Na+ results i hyperpolarisation

Question 36

the dark current opens in what light setting

Answer 36

in the dark

Question 37

the dark current channels closes in response to what

Answer 37

light

Question 38

the dark current channel is permeable to what ion

Answer 38

Na+

Question 39

the dark current channels keeps the Vm of photoreceptors what charge

Answer 39

positive

Question 40

what facilitates high acuity

Answer 40

distribution of rods and cones

Question 41

what light setting are rods good for seeing in

Answer 41

dim light

Question 42

what light setting are cones good for seeing in

Answer 42

normal daylight

Question 43

in the ON/OFF pathways, when is glutamate inhibited

Answer 43

in the on pathway

Question 44

what are the only cells in the eye that can produce action potentials

Answer 44

ganglion cells (some amacrine)

Question 45

RETINAL PROCESSING lateral inhibition is by what cell

Answer 45

horizontal cells

Question 46

CENTER-SURROUND ORGANISATION IN THE RETINA horizontal cells interconnect a group of 'surround' neurons. It samples the total amount of excitation in that surround and responds by releasing what

Answer 46

GABA

Question 47

CENTRE-SURROUND ORGANISATION IN THE RETINA If there is low surround, then there is ____ GABA released

Answer 47

less

Question 48

what are the two types of ganglion cells

Answer 48

M-type P-type

Question 49

what are the differences between the M type and P type ganglion cells

Answer 49

M type: large receptive fields, transient activation P type: smaller receptive fields, sustained activity, colour sensitive

Question 50

what does LGN stand for

Answer 50

lateral geniculate nuceli

Question 51

what are the two types of LGN

Answer 51

magnocellular LGN parvocellular LGN

Question 52

INPUTS TO THE STRIATE CORTEX magnocellular LGN neurons project to what layer

Answer 52

Layer IVCalpha

Question 53

INPUTS TO THE STRIATE CORTEX Parvocellular LGN neurons project to what layer

Answer 53

IVCbeta

Question 54

INPUTS TO THE STRIATE CORTEX Koniocellular LGN axons project to what layer what layer do they bypass

Answer 54

by pass layer IV to make synapses in layers II and III

Question 55

in the striate cortex, most neurons in layer III are what

Answer 55

binocular

Question 56

vision for perception the ventral pathway projects to where in the brain

Answer 56

projects to occipitotemporal ass cortex

Question 57

vision for action the dorsal pathway project where in the brain

Answer 57

project to parietao occipital ass cortex

Question 58

what is Hebb's postulate

Answer 58

neurons know that they are around others of the same eye