Exam 2-Vision Flashcards
(67 cards)
1
Q
Rhodopsin
A
- photopigment in rods
- 2 parts=opsin (protein) and retinal (lipid)
- breaks apart in light
- when bound together rhodopsin is in 11-cis form (in darkness)
- absorption of light changes retinal from 11-cis to all-trans form which causes rhodopsin to break apart
2
Q
cGMP
A
opens Na channels when it binds
3
Q
Receptive field of bipolar cell
A
sum of all photoreceptor inputs feeding into it
4
Q
Transduction
A
transformation of sensory info into neural signals
5
Q
Photon
A
- particle of light
- always travel at same speed BUT vary in amount of energy they possess which gives us waves with different wavelengths/amplitudes
6
Q
Absorption
A
ability to retain something rather than reflect or transmit it to another location
7
Q
Reflection
A
bending back of light toward the source
8
Q
Refraction
A
deflection, or changing or direction of light at a boundary (such as between air and water)
9
Q
sclera
A
white outer covering of eye
10
Q
cornea
A
- transparent outer layer
- begins process of refracting light to form an image in back of eye
11
Q
anterior chamber
A
- area behind cornea
- contains aqueous humor
12
Q
pupil
A
-opening in front of eye controlled by iris
13
Q
iris
A
- circular muscle that controls size of pupil
- color is controlled by melanin, blood supply and connective tissue
14
Q
optic disk
A
gap in retina where optic nerve leaves eyeball
15
Q
retina
A
- visual image is focused on retina
- visual image is inverted (top to bottom) and reversed (left to right)
16
Q
ganglion cells
A
- retinal cell layer
- axons leave eye as part of optic nerve
- first place where there are APs (graded potentials are converted to APs)
17
Q
bipolar cells
A
- between ganglion cells and rods/cones (photoreceptors)
- forms part of straight pathway between ganglion cells and photoreceptors
- *-either hyperpolarize or depolarize depending on what kind of glutamate receptor they have
- activated or inhibited by photoreceptors
18
Q
photoreceptors
A
- sensory cell in retina that responds to light
- rods and cones
- outer segments contain photopigments (chemicals that interact with light)
- membrane potential is about -30mV in darkness
- depolarized in dark, hyperpolarized in light
- graded release of glutamate (more depolarization=more NT released)
19
Q
horizontal cell
A
- retinal interneuron
- located in inner nuclear layer
- integrates signal from across the surface of the retina
- output from photoreceptors
20
Q
scotopic vision
A
ability to perceive visual stimuli in near darkness due to activity of rods
21
Q
photopic vision
A
ability to perceive visual stimuli under bright light conditions due to activity of cones (have 3 different photopigments)
22
Q
on-center bipolar cell
A
- turned on when light hits center
- depolarized in light
- inhibited by glutamate
- mGluR receptor
23
Q
off-center bipolar cell
A
- turned off when light hits center
- inhibited by light
- depolarized in dark
- excited by glutamate
- kainate receptor
24
Q
3 types of ganglion cells
A
- parvocellular (P)
- magnocellular (M)
- koniocellular (K)
25
parvocellular (P) cells
- small ganglion cell
- respond to high contrast and color
- near fovea
- convey details
- 70% of ganglion cells
26
magnocellular (M) cells
-large ganglion cell
-respond to all wavelengths
-large receptive field
(magno=large)
27
koniocellular (K) cells
- ganglion cell
| - responds to blue and yellow light
28
optic chiasm
crossing of optic nerves
| -after optic chiasm, they are referred to as optic tracts
29
From the eyes, axons can go...
1) thalamus (lateral geniculate nucleus)
2) hypothalamus (suprachiasmatic nucleus)
3) superior colliculus
30
Lateral geniculate nucleus (LGN)
- nucleus in the thalamus
- layered structure, bent in middle
- magnocellular and parvocellular layers
- retinotopic map of contralateral visual hemifield
31
Magnocellular layers of LGN
ventral layers that receive input from M cells in retina
32
Parvocellular layers of LGN
dorsal layers receiving input from P cells in retina
33
striate cortex
primary visual cortex
34
simple cortical cells
- respond to stimuli shaped like bars or edges that have particular slant/orientation on particular location of retina
- probably helps perceive shapes
35
Dorsal stream
"where"
| -movement, location, grasping/reaching
36
Ventral stream
"what"
| -object recognition
37
Fusiform face area
- extrastriate area in temporal lobe that recognizes familiar faces
- ventral stream
38
Trichromatic theory
- color vision is based on our possessing three different color photopigments
- proposed three different color receptors in retina
- does account for some components of color vision but not all (afterimage)
- color encoded at photoreceptor level
- long wave=red cones
- medium wave=green cones
- short wave=blue cones
39
Opponent process theory
-color vision based on 3 antagonistic color channels:
red/green, blue/yellow, black/white
-color encoded at ganglion level
40
Amblyopia
- lazy eye
- one eye can't focus on objects
- brain learns to ignore input from less functional eye
41
Cataract
clouding of lens
42
Myopia
- nearsightedness (can see well close up but not far away)
| - acuity problem resulting from elongated eyeball
43
Hyperopia
- farsightedness (can see well far away but not close up)
| - acuity problem resulting from short eyeball
44
Astigmatism
distortion of vision caused by the shape of the cornea
45
Visual agnosias
disorders in which a person can see a stimulus but doesn't recognize what they are seeing
46
Striated muscle
cardiac and skeletal muscle
47
Muscle fibers
long, thin muscle cell
| -each is encased in membrane with ACh receptors
48
Myofibrils
long strands of protein inside muscle fiber
| -responsible for producing fiber contractions
49
Sarcomere
single segment of myofibril
50
Myofilaments
actin and myosin
| -make up myofibril
51
Sliding filament model (muscle contraction)
- AP triggers release of Ca
- Ca binds troponin
- Displaces tropomyosin
- actin binds myosin
- muscle contracts
52
3 types of myosin filaments
- type 1
- type2a
- type2b
53
Type 1 fiber
- slow twitch
- aerobic metabolism
- endurance
54
Type 2a fiber
- fast twitch
- anaerobic metabolism
- powerful movements
- fatigue resistant
55
Type 2b fiber
- similar to 2a but quicker
| - can get fatigued
56
alpha motor neuron
spinal motor neuron
- form connections with muscles at neuromuscular junction (ACh is NT)
- directly responsible for contracting muscles
57
Motor unit
alpha motor neuron and all muscle fibers it innervates
| -includes either fast or slow twitch fibers but not a mixture of both
58
Rate code
variations in firing rate of motor neurons to meet need for a certain amount of contraction
59
Recruitment
process of gradually activating motor units as load on muscle increases
-slow twitch fibers recruited first
60
Extrafusal muscle fibers
outside spindle
| -responsible for contracting muscle
61
Intrafusal muscle fibers
inside spindle
- own set of motor neurons called gamma motor neurons
- give info about muscle length/stretch
62
3 types of muscular spindles
- dynamic nuclear bag (info about speed and change in muscle length)
- static nuclear bag (info about muscle length)
- nuclear chain fiber (info about muscle length)
63
1a sensory fibers
wrapped around middle of spindle fiber
| -generate APs when muscle spindle stretches, gives info about length and velocity
64
Group II sensory fibers
static nuclear bag fibers and nuclear chain fibers
| -info about stretch
65
Corticobulbar tract
- connects primary motor cortex with cranial nerve nuclei
| - manages movement of head/neck
66
Lateral pathways
- originate in cortex
- synapse in red nucleus or alpha motor neurons
- controls voluntary movements
67
Ventromedial pathways
- originates in brainstem
| - subconscious movements of neck and torso
