unit 2 Flashcards
(195 cards)
1
Q
light
A
is a type of electromagnetic energy; has prpoerties of both a wave and particle
2
Q
light has discreet units of
A
protons
3
Q
BRIGHT light
A
= high luminance = many protons
4
Q
DIM light
A
= low luminance = fewer photons
5
Q
equation of energy
A
E = h/wavelength
6
Q
energy has a direct relationship with
A
h (frequency)
7
Q
energy has an indirect relationship with
A
wavelength
8
Q
when light strikes surface
A
undergoes changes including absorption, dispersion, transmission, and refraction
9
Q
3 layers of the eye
A
outer, middle and inner
10
Q
outer
A
sclera/cornea
structure and protection
cornea helps focus light into retina
11
Q
middle
A
choroid and ciliary body
contains refraction pigmented epithelium and provides blood flow to eye
12
Q
inner (retina)
A
phototransduction
13
Q
phototransduction
A
process by which light energy is converted into electrical signals
14
Q
aqueous humor
A
majorly found in anterior chamber and produced by ciliary body
function is to provide nutritive support to avascular cornea
15
Q
vitreous humor
A
found in vitreous chamber; makes up most of volume in the eye
16
Q
sclera
A
main component of outside of eye - provides shape and protection
17
Q
cornea
A
most refracting power; protects eye; possesses majority of focusing power of eye by refracting light as it enters eye and focusing it onto the retina
18
Q
lens
A
also refractions light onto retina but extent of refraction can be altered depending on distance of an object (accommodation)
19
Q
ciliary body
A
produces aqueous humor - alos contains ciliary muscles
20
Q
ciliary muscles
A
controls shape of lens via zonule fibers
21
Q
iris
A
surrounds pupil; contains sphincter and dilator muscles that control the size of pupil thus modulating the amount of light that enters the eye - under autonomic control
22
Q
sphincter
A
parapsympathetic
23
Q
dilator
A
sympathetic
24
Q
pupil
A
hole that allows light to enter the eye
25
fundas
surface of retina - as visualized by a fundascope
26
optic disc
region of retina where axons from RGCs join together to leave the eye as optic nerve (CN II) = info leaves eye
no photoreceptors here = blind spot
27
optic nerve
CN II
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fovea
an avascular region of retina and highest visual acuity - highest concentration of cones and no RGCs
29
retina layers
3 layer (laminar) structure: photoreceptor cells, bipolar, retinal ganglion, horizontal cells amacrine cells, Muller glia
30
light stim are...
transduced into electrical stim by photoreceptors (rods and cones)
31
output of retina are
RGC - project to various regions in brain via optic nerve
32
pathway IN EYE
photoreceptors --> bipolar cells --> retinal ganglion cell --> optic nerve (CN II)
33
what cells are closer to back of eye
photoreceptors
34
what cell is closer to front of eye
RGCs
35
which cells only do graded receptor potentials (PSPs)
photoreceptor and bipolar cells
36
which is the only cell that fires AP and why
RGCs
becuase their signals need to travel very far and very fast compared to the others
37
what cells need to be transparent
bipolar and RGCs
38
rods
detecting light intensity; color insensitive opsine: rhodopsin: more sensitive to photons
larger change in membrane potential induced by same intensity of light stimulus
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cones
detecting color; synapse directly onto bipolar cells whereas rods --> amacrine cells --> bipolar through gap junction
color vision mediated by wavelength specific opsins/photopigments found in cones
40
rods versus cones
located in different parts of retinal; structural difference/general shape
41
overall function of eyes
to focus light onto retina and transmit signal to brain
42
what is needed to eyes to function
must contain transparent structures to allow light to reach the retina: cornea, lens, aqueous humor, vitreous humor
must focus light energy onto retina - refraction via cornea and lens
must be able to convert light energy into electrical stimulus (phototransduction) via photoreceptor cells
43
INDEPTH pathway of EYE
light traveling towards eye --> refracted via cornea --> travels thru aqueous humor and pupil --> refracted via lens --> travels thru vitreous humor --> strike retina --> forms upside down representation of world on retina
44
accommodation
the process through which the lends focuses on near objects
45
at accommodation baseline
focusing on object in distance, lens is flattened, capillary muscle not constricted, zonule fibers are stretched out
46
during accommodation
focus on near object by contracting the capillary muscle -- changing shape of lens and thus its refracting capacity (lens thickened)
leads to loosing of zonule fibers allowing lens to assume native state
47
ciliary muscle contraction is controlled by
oculomotor nerve (CN III)
48
cataracts
caused by opaque lens - common result of age - most common cause of blindness in world
49
mucular degeneration
most common cause of age-related blindness in US
50
wet form mucular degeneration
vascularization of macula
51
dry form mucular degeneration
caused by "drusen" deposits on macula
52
photoreceptor cells responsible for....
transduction of energy from physical world (light) into electrical energy in brain (electrical potential)
53
light HYPERPOLARIZES cell
leading to reduction of glutamate
54
absorption of photons by photoreceptors
--> hyperpolarization --> decreased glutamate release
55
resting membrane potential
relatively high - -40mV
high release of glutamate at baseline
56
retinal isomerization
opsin molecules (rhopsin) contains photopigments (retinal) that becomes isomerized when light
57
rhodopsin is
protein sitting in cell membrane of a rod
58
rhodopsin is coupled to
g-protein but responding to light stim
59
11-cis retinal + light
= ALL-trans retinal --> g-protein (transducin)
60
g-protein (Ga)
active cGMP PDE so decreased cGMP -- no Na+ and Ca2+ influx - hyperpolarization
61
DARK area
cell is relatively depolarized - glutamate release is high
62
LIGHT area
cell is relatively hyperpolarized - glut release is low
63
light area process
light --> activation of transducin (g-protein) --> decreased intracellular levels of cGMP by activating cGMP-PDE --> decrease Na+ and Ca2+ currents through cGMP-gated channels --> hyperpolarization of photoreceptor cells --> decreased Ca2+ influx --> decreased glutamate release from photoreceptors
64
light and dark stim are processed by
ON-center and OFF-center neurons in retina
65
ON-center ganglion cell
increase firing when light presented
66
OFF-center ganglion cell
decrease firing when light presented
67
ON-center bipolar cells
activated by light
68
OFF-center bipolar cells
inhibited by light
69
how do ON-center and OFF-center neurons communication
ON-center communicate with ON-center and vice versa
70
how does glutamate impact bipolar cells
it can active or inhibit them depending on receptor expression
71
bipolar cells with AMPA receptor will be ____ by glutamate because...
activated.... cation channels allow Na+ to flow into cell --> depolarization --
take away activation = inhibition
72
bipolar cells with mGluRG receptors (metabotropic) _______ neuronal activity because
inhibit neuronal activity
take away inhibition --> activation
73
horizontal cells
surround inhibition - sharpen receptive fields by inhibiting surround photoreceptive cells
74
thalamus (LGN)
visual perception
75
midbrain (superior colliculus)
visual reflexes and eye movement
76
midbrain (pretectal area)
modulation of pupil size
77
hypothalamus (suprachiasmatic nucleus)
sleep cycle modulation
78
retinotopy
specific parts of visual field are "mapped onto" (represetned) in specific parts of retina and brain
79
superior colliculus does two things
visual tracking and reflexes
80
visual tracking
eye movements that occur while following an object
81
visual reflexes
activate neck muscles that reposition the head to orient to a stimulus
82
sensorimotor structure
using sensory movement to fine tune movement
83
pupillary reflex
afferent: sensing light levels and info gets carried to CN II
efferent: activating pupillary (iris) sphincter muscle and carried to CN III
used to constrict the pupils when light is being shone in the eye
84
suprachiasmatic chiasm
part of hypothalamus (homeostasis) that uses light signals to modulate sleep-wake cycle
85
pathway BRAIN
light --> eye -- partially decussation at chiasm when traveling through optic nerve/tract--> synapses in LGN --optic radiations--> synapse at primary visual cortex (V1) in occipital lobe
86
decussation
axons crossed at midline
87
partial decussation
some axons cross midline - some dontip
88
ipsilateral
pathway stays on same side
89
contralateral
pathway crossed midline
90
info from visual field...
strikes both eyes except more peripheral monocular field
91
axons leaving RGCs of nasal hemiretina will cross at...
optic chiasm
92
most peripheral portion of visual field
is processed through nasal hemiretina (will decussate) of ipsilateral eye of ipsilateral eye
93
from contralateral eye will strike...
temporal hemiretina
94
binocular
both eyes can see most of visual field
95
dorsal stream
"where" stim is in space
96
ventral stream
"what" is the stim
97
lesion in optic nerve
right optic nerve lesion = right peripheral (monocular) visual field loss and vice versa for left
98
lesion in optic chiasm
pituitary tumor --> tunnel vision
99
sound is produced by
variations in air pressure
100
properties of sounds
are the same as properties of light
101
frequency
(Hz) pitch
102
amplitude
volume (Db)
103
complexity
timbre
104
attenuation reflex
muscles attached to ossicles can tighten bones of inner ear, affecting their ability to stimulate the oval window
105
AR muscle 1
tensor tympani, innervated by trigeminal nerve
106
trigeminal nerve
CN V; sensory to face
107
AR muscle 2
stapedius, innervated by facial nerve
108
facial nerve
CN VII; motor to face
109
cranial nerves are
a collection of axons in the PNS; typically correspond to face and correspond to brain stem (nuclei/cell bodies are in brain stem)
110
outer/external ear
collect sound wave: pinna/auricle (ear) --> external auditory canal --> tympanic membrane (eardrum)
111
how does the orientation of the pinna impact sound
because of how funnel is oriented - can hear front and to side better
112
middle ear
transmit sound waves from eardrum to oval window
113
oval window
border between middle and inner ear
114
from eardrum to over window
eastachain tube and three ossicles
115
eastachian tube
connect middle tube to nasal cavity for pressure and no build up
116
three ossicles
malleus, incus, stapes
117
PATHWAY FROM OUTER TO INNER
sound waves --> tympanic membrane --> malleus --> incus --> stapes --> oval window
118
cochlea
3 main chambers and contains sensory receptors - the organ of corti
119
3 main chambers of cochlea
scala vestibuli: perilymph
scala media: endolymph
scala tympani
120
inner ear
transduce sound waves into electrical signal; when stapes hits oval window, causes movement of fluid in cochlea
121
endolymph
high potassium, low sodium
122
scala media
have hair cells that are anchored in basilar membrane (within organ of corti)
123
hair cells
stereocilia and kinocilia are anchored in tectorial membrane (endolymph filled)
124
conductive earing loss
problem in external/middle ear - signal cant get to cochlea
125
sensorineural hearing loss
signal cant be sent to brain but is sent to cochlea
126
rinne test
using tuning fork and applying it to bone or air to see which can hear better with - if can hear on bone but not air = conductive hearing loss
127
mechotransduction
movement in fluid in cochlea causes basilar membrane to vibrate causing bending of stereocilia and kinocilia
128
bending of stereocilia towards kinocilia
DEPOLARIZATION via opening of K+ channels
129
tiplinks
bonding cilia physically together
130
bending away from kinocilia
HYPERPOLARIZATION
131
mechanoreceptors on end of cilia when bend
they open and let K+ in or out --> VG Ca+ channels open with depolarization --> glut release --> stimulates peripheral process of neurons that make up cochlear branch of vestibulocochlear nerve
132
vestibulocochlear nerve
CN VIII
133
two branches of CV VIII
cochlear branch: coming from cochlea - hearing
vestibular branch: coming from vestibule - involving balance and eye movements
134
two types of hair cells
inner and outer
135
inner hair cells
provide most output from cochlea (can't lose them)
136
outer hair cells
amplify signal -- are a LOT weaker than inner hair cells
contain motor proteins (prestins) which change length of hair cell -- affects how much cilia bend
137
PATHWAY IN CNS
is bilateral after cochlear nucleus synapse
cochlea (hair cells --> spiral ganglion) --> cochlear nucleus --> superior olive --> inferior colliculus --> medal geniculate nucleus --> primary auditory cortex (in temporal lobe)
138
stimulus intensity
louder sound --> greater amplitude of basilar membrane --> stronger activation of hair cells --> INCREASED FIRING RATES
139
tonotopy
specific regions of basilar membrane are stimulated by specific sound frequencies, which corresponds to a specific pitch, which project to specific parts of cochlear nucleus and primary auditory cortex
140
interaural time delay
sound infront reaches each area at same time; as it goes closer to one side there is more of a difference between ears
141
vestibular system
has otolith organs and semicircular canals
142
otolith organs
utricle and saccula: detect changes of head angle and linear acceleration
143
semicircular canals
detect head movement, angular acceleration
144
special sense
have special sensory organs dedicated to them, sensory info reaches CNS via CN
145
skin (and muscles, joints, organs)
sensory organs for somatosensation
146
info reaches CNS
via peripheral nerve (unless info from face)
147
somatosensation
sensation of the body - soma = body in greek
148
proprioception
position of body in space - mediated by sensory receptors in muscles, joints and skin (can be conscious or unconscious)
149
exteroception
sense of direct interaction with world as it impacts body: touch and temperature/pain
150
interception
sensation associated with organs, important for automatic regulation
151
nociception
pain/temperature
152
conscious
skin --> spinal cord --> brainstem --> thalamus --> primary somatosensory cortex
153
unconscious
skin --> spinal cord --> brainstem --> cerebellum
154
spinal cord anatomy
gray matter on inside - dorsal and ventral horn - contains primarily cell bodies
white matter on outside - myelinated axons (tracts)
155
ascend to brain
sensory
156
descend
motor
157
dorsal root/horn
incoming sensory info from periphery
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ventral root/horn
outgoing moto info to periphery
159
spinal nerves will eventually become
peripheral nerves
160
segmental organization of spinal cord
different "levels" of spinal cord
161
cervical
upper extremity
162
troasic
trunk
163
lumbar and saural
lower extremity
164
dermatume
a specific region of body that maps to a specific spinal cord segment --> each segment of spinal cord receives info from a particular part of the body
165
dorsal root ganglion cells
carry somatosensory info from body into spinal cord via dorsal root
166
pseudo-unipolar morphology
all somatosensory info carried to CNS via DRG cells
167
all afferent/somatosensory info enters thru
dorsal root and either synapses in grey matter or medulla
168
different fiber types carry different modalities of somatosensory info relate to
size, myelination status, function
169
axon size
decrease axial resistance
170
myelination state
increase membrane resistence
171
fiber types
1a, 1b, A-beta, A-delta, c-fibers
172
1a
largest axonal diameter, myelinated, carries info on muscle stretch from muscle spindle - proprioception
173
1b
second largest diameter, myelinated, carries info on force of muscle contraction from golgi tendon organ - proprioception
174
A-beta
middle axonal diameter, myelinated, carries info from a variety of mechanoreceptors in skin and joints - exteroception (minus pain and temp)
175
A-delta
second smallest axonal diameter, myelinated, sharp, localized pain - pain and temp and free nerve endings
176
c-fibers
smallest axonal diameter, unmyelinated, dull, burning pain - pain and temp and free nerve endings
177
trigeminal nerve (CN V)
carries somatosensory info from face and contains neurons that are analogous to DRG cells
178
mechanoreceptors are
activated by physical distortion
179
receptor cell
connective tissue/protein receptor (both mechanoreceptors) --> DRG cell
180
muscle spindle
detects muscle stretch --> main receptor for proprioception; activated when muscle stretches
181
golgi tendon organ
detects force of muscle contraction
182
mechanoreceptor affects DRG cell's
receptive field and adaptive field
183
receptive field
how much area is covered by this DRG cell
184
adaptive field
if apply prolonged stim, how many aps will be fired/will it stop/adapt
185
bare/free nerve endings
pain and touch
186
dorsal spinocerebellar pathway
unconscious proprioception for lower extremity --> allows motor system to use sensory info to coordinate movement
cerebellum uses unconscious proprioceptive info to coordinate movement
187
dorsal spinocerebellar pathway PATHWAY
mechanoreceptors activated (1a, 1b, A-beta) --> DRG --> spinal cord --> synapses in gray matter (column of clarke) --> ascends in d9orsal spinocerebellar tract --> signal goes to ipsilateral cerebellum
188
dorsal column pathway
conscious proprioception and exteroception for entire body: fine touch, vibration, etc.
189
dorsal column pathway PATHWAY
mechanoreceptors activated (1a, 1b, A-beta) --> DRG --> ascends in dorsal column --> brain stem --> synapse in medulla --> synapse in CONTRALATERAL thalamus (VPL) --> primary somatosensory cortex
190
anterolateral pathway
pain and temperature
191
anterolateral pathway PATHWAY
mechanoreceptors activated (A-delta, c-fibers) --> DRG --> spinal cord --> synapses in dorsal root --> decussates and then ascends anterolateral tract --> synapse in thalamus (VPL) --> primary somatosensory cortex
192
somatotopy in cortex
particular parts of body "map" to particular parts of primary somatosensory cortex
193
somatosensory homunculus
face and arm region map to more lateral parts to cortex
legs and urogenital region map to most medial part of cortex
194
body info carried to
spinal cord by DRG neurons and transmitted to VPL thalamus
195
face info carried to
brainstem by CN V and transmitted to VPM thalamus
