Visual 2 Flashcards
(88 cards)
1
Q
These are mores sensitive to light and have slow integration time
A
rods
2
Q
These have poor spatial resolution
A
rods
3
Q
These have more pigment and are less directionally sensitive
A
rods
4
Q
These are less sensitive to light and have fast integration time
A
cones
5
Q
These give us high spatial resolution
A
cones
6
Q
These hae less pigments and are directionally sensitive
A
cones
7
Q
Per eye you have______ rods
and ____cones
A
100 million
5 million
8
Q
Key dif btwn rods and cones are rods
A
saturate
9
Q
At low levels of light, rod …
A
reaches its max response, at room level, rods are saturated
10
Q
Most of the time,vision is based on
A
cones or 5% of photoreceptors
11
Q
Photorecetpors _____ in response to light
A
hyperpolarize
12
Q
Photopigment =
A
chomophore + opsin
13
Q
Chromophore conformation is
A
11-cis retinal
14
Q
photopig is embedded in
A
OS layer (80% OS is photopigment)
15
Q
11-cis-retinal absobs light at
A
375 nm
16
Q
Opsin will “_____” absorption spectrum
A
red shift
17
Q
Changes in chromophore will….
A
initiate transduciton
18
Q
what kind of protein receptor is photopigmetn
A
GPCR with chormophore burried in middle
19
Q
rods absorb strongest in
A
blue-green
20
Q
photopigments are characterized by:
A
efficiency with which they absorb light of diff wavelengths
21
Q
photoreceptors cant register the wavelenth of photons the catch “the output depends on quantum catch, but not upon WHICH quanta are caught”
A
concenpt of univariance
22
Q
Photoreceptors are _______
A
colorblind
23
Q
How do we tell what dif types of colors we see
A
photoreceptors give input to ganglion cell based on quantam catch
24
Q
Once we absorb light, begin phototransduction which begins with:
A
Isomerization: shift from 11-cis to all trans conformation as we slam against the transmembrane domain
25
Isomerization from 11-cis chromophore to all trans will cause:
activaiton of opsin protein
26
Once Opsin is activated, it will activate
transducin (g protein)
27
Once transducine is activated it will
activate PDE
28
PDE will do what to cGMP
turn it to GMP which closes ion channels
29
low cGMP closes ion channels resulting in
hyperpolarization (inward flux of Ca++ and Na+ blocked)
30
path of phototransduction
isomerization-->opsin-->transducin-->PDE--> takes cGMP to GMP--> results in hyperpolarization
31
Where is atRAL reduced to all trans retionol (atROL)
outter segment via NADPH all trans retinal specific dehydrogenase
32
this guy is a slave to photoreceptor regeneration
RPE
33
this guy transferes at ROL across the IPM
IRBP
34
which degernates first, cones or rods
rods, bc cones have alternate source of 11cRAL other then RPE
35
viagra has this and can interfere with basic phototransduction and lead to changes in rod and cone OS function
PDE5 inhibitors
36
light falling w/in receptive field of a neuron influences the activity of that neuron
every neuron that is higher order than the photoreceptor has a 'field' of photoreceptors that give it input
concentp of receptive field
37
All photoreceptors will ______ in reponse to light
hyperpolarize
38
when photoreceptors hyperpolarize they...
release less NT
39
Photoreceptrs are _____ cells because light hitting them turns them_____
OFF
| OFF
40
when there is no light on a photreceptor it will
depolarize and release glutamate
41
Photoreceptors hyper and depolarize in a ______ fashion and relase NT's in the same manner
graded
42
Photoreceptors do or do not produce action potentials
DO NOT!!!!
43
When a cone is depolarized it will release
glutamate (ig it's excitatory, but not always)
44
Cones respond to light the same way, but single cone gives rise to
2 parallel pathways via connecting 2 dif bipolar cell types
45
The bipolar cell that is "ON" center
Light in it's receptive field results in _____
and they have ______ synase with cone
cell depolarizing
| sign reversing
46
On center bipolar cells have ______ contacts to coens
invaginating
47
On center bipolar cells act like a
classical inhibitory synapse
48
What will cause a hyperpolarizing effect on a ON center bipolar cell
glutamte that is released then the OFF center cell is in dark and depolarized
49
OFF center bipolar cell will ______ when light hits the center of our OFF center photoreceptor
hyperpolarize
50
The OFF center bipolar cell is considered _______ to the OFF center cone it synapses with
sign conserving
51
OFF center bipolar cells have _____ contact with OFF center photoreceptor
flat/basal
52
OFF center bipolar cells have _____ receptors
ionotropic
53
ON center bipolar cells ahve ______ receptor
metaborotropic
54
What is the point of parallel pathways
improved sensitivity
one provides info about stimuli that are brighter than background (ON-center) while the other provides info on stimuli dimmer then background (OFF-center)
55
Bipolar cells talk to
1. Amacrine--for lateral connections
2. Ganglion cells--to produce AP
3. Parasol ganglions cells and midget ganglion cells
56
large cells w/ large receptive fields, more transient and project to magno layers (only 10%)
parasol cells
57
project to parvo layers, smaller cells w/ small receptive field and more sustained (make up 90%)
Midget ganglion cells
58
Two parallel bipolar cells connect to
like minded ganglion cell (sign-conserving)
59
Photoreceptors are completely synpaptically interconnected by an elaborate system of inhibitory interneurons called
horiozontal cells
60
these guys laterally interconnect cones with other cones
horizontal cells
61
every cone has a recipricol ______ synaptic relationship with all its neighbors
inhibitory
62
When a cone is excited (depolarized) it _____ horizontal cells it synpases with
excites
63
Excited horizontal cells will _______ neighbor cones via ______
inhibit
| GABA
64
the action of a depolarized horizontal cells is to
hyperpolarize the cones it synapses with
65
The result of horiztonal cells is
enhanced edges
66
Lateral inhibition gives us
imporoved resolution: increaes our ability to recognize edges
67
Neurons responding to edge of a stimulus respond ______ then neurons responding to middle
more strongly
68
Edge neurons recieve inhibition from neighbros on only one side, the side____
away from edge
69
Neurons stimulated from the middle of a surface get:
inhibition from all sides
70
Light falling in the region surrounding the photoreceptor, but not directly on it, turns the photoreceptor
ON
71
What is our protein component of our rods
rhodopsin
72
Rhodopsin mutations will alter _____ fnx
rod
73
Rhodopsin mutations can
disrupt transport to OS, be retained in ER and affect stability of post-translation modification thus get constituitve activation
74
characterized by progressive loss of rod and cone receptors with accompying vision loss
Retinitis pigmentosum
75
Nighblindness is early symptoms with progressive constriction of visual field
RP
76
Inheritence of RP
X-linked autosomal dom or recessive
77
pigments that migrate from the RPE and adhere to blood vessels in RP will affect this first
rods
78
most common form of deaf/blindness
Usher
79
progressive vision/hearing loss, reduced odor identification, vestibular dysfuntion d/t motor proteins
Usher
80
Usher is dt defects in
sensory cilia, core of sterocilical
81
```
Congenital defects are
____ at birth
same/worse though life
can/cannot be classified easily
affects one or both eyes equally
```
present at brith
same through life
can be classified
both eyes equal
82
visual aquity is often unaffected with confenital color vision defects: t/f
true
83
congenital vision affects males or females more
males
84
congentical color vision defects is usuallY;
protan or deutan
85
```
Aquired color vision:
Onset____
type and severity_____
_____ differences occur
Visual acuity is ______
Predominately_____
affects males/females
```
```
after birth
type and severity fluctuates
Monocular diff occur (not both eyes same)
reduced visual aquity
predom tritan
equal in male and female
```
86
Achromoatopsia causes defect in:
CNG-betta, CNGA-3, GNAT2 (transducin)
87
In achromatopsia cones:
cannot hyperpolarize in resposne to light
88
affected ind w/ achromatopsia have:
no cone function
