unit 2 Flashcards

1
Q

light

A

is a type of electromagnetic energy; has prpoerties of both a wave and particle

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2
Q

light has discreet units of

A

protons

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3
Q

BRIGHT light

A

= high luminance = many protons

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4
Q

DIM light

A

= low luminance = fewer photons

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5
Q

equation of energy

A

E = h/wavelength

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6
Q

energy has a direct relationship with

A

h (frequency)

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7
Q

energy has an indirect relationship with

A

wavelength

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8
Q

when light strikes surface

A

undergoes changes including absorption, dispersion, transmission, and refraction

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9
Q

3 layers of the eye

A

outer, middle and inner

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10
Q

outer

A

sclera/cornea
structure and protection
cornea helps focus light into retina

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11
Q

middle

A

choroid and ciliary body
contains refraction pigmented epithelium and provides blood flow to eye

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12
Q

inner (retina)

A

phototransduction

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13
Q

phototransduction

A

process by which light energy is converted into electrical signals

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14
Q

aqueous humor

A

majorly found in anterior chamber and produced by ciliary body
function is to provide nutritive support to avascular cornea

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15
Q

vitreous humor

A

found in vitreous chamber; makes up most of volume in the eye

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16
Q

sclera

A

main component of outside of eye - provides shape and protection

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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

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18
Q

lens

A

also refractions light onto retina but extent of refraction can be altered depending on distance of an object (accommodation)

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19
Q

ciliary body

A

produces aqueous humor - alos contains ciliary muscles

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20
Q

ciliary muscles

A

controls shape of lens via zonule fibers

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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

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22
Q

sphincter

A

parapsympathetic

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23
Q

dilator

A

sympathetic

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24
Q

pupil

A

hole that allows light to enter the eye

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25
Q

fundas

A

surface of retina - as visualized by a fundascope

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26
Q

optic disc

A

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

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27
Q

optic nerve

A

CN II

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28
Q

fovea

A

an avascular region of retina and highest visual acuity - highest concentration of cones and no RGCs

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29
Q

retina layers

A

3 layer (laminar) structure: photoreceptor cells, bipolar, retinal ganglion, horizontal cells amacrine cells, Muller glia

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30
Q

light stim are…

A

transduced into electrical stim by photoreceptors (rods and cones)

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31
Q

output of retina are

A

RGC - project to various regions in brain via optic nerve

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32
Q

pathway IN EYE

A

photoreceptors –> bipolar cells –> retinal ganglion cell –> optic nerve (CN II)

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33
Q

what cells are closer to back of eye

A

photoreceptors

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34
Q

what cell is closer to front of eye

A

RGCs

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35
Q

which cells only do graded receptor potentials (PSPs)

A

photoreceptor and bipolar cells

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36
Q

which is the only cell that fires AP and why

A

RGCs
becuase their signals need to travel very far and very fast compared to the others

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37
Q

what cells need to be transparent

A

bipolar and RGCs

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38
Q

rods

A

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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39
Q

cones

A

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

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40
Q

rods versus cones

A

located in different parts of retinal; structural difference/general shape

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41
Q

overall function of eyes

A

to focus light onto retina and transmit signal to brain

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42
Q

what is needed to eyes to function

A

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

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43
Q

INDEPTH pathway of EYE

A

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

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44
Q

accommodation

A

the process through which the lends focuses on near objects

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45
Q

at accommodation baseline

A

focusing on object in distance, lens is flattened, capillary muscle not constricted, zonule fibers are stretched out

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46
Q

during accommodation

A

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

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47
Q

ciliary muscle contraction is controlled by

A

oculomotor nerve (CN III)

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48
Q

cataracts

A

caused by opaque lens - common result of age - most common cause of blindness in world

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49
Q

mucular degeneration

A

most common cause of age-related blindness in US

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50
Q

wet form mucular degeneration

A

vascularization of macula

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51
Q

dry form mucular degeneration

A

caused by “drusen” deposits on macula

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52
Q

photoreceptor cells responsible for….

A

transduction of energy from physical world (light) into electrical energy in brain (electrical potential)

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53
Q

light HYPERPOLARIZES cell

A

leading to reduction of glutamate

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54
Q

absorption of photons by photoreceptors

A

–> hyperpolarization –> decreased glutamate release

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55
Q

resting membrane potential

A

relatively high - -40mV
high release of glutamate at baseline

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56
Q

retinal isomerization

A

opsin molecules (rhopsin) contains photopigments (retinal) that becomes isomerized when light

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57
Q

rhodopsin is

A

protein sitting in cell membrane of a rod

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58
Q

rhodopsin is coupled to

A

g-protein but responding to light stim

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59
Q

11-cis retinal + light

A

= ALL-trans retinal –> g-protein (transducin)

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60
Q

g-protein (Ga)

A

active cGMP PDE so decreased cGMP – no Na+ and Ca2+ influx - hyperpolarization

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61
Q

DARK area

A

cell is relatively depolarized - glutamate release is high

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62
Q

LIGHT area

A

cell is relatively hyperpolarized - glut release is low

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63
Q

light area process

A

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

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64
Q

light and dark stim are processed by

A

ON-center and OFF-center neurons in retina

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65
Q

ON-center ganglion cell

A

increase firing when light presented

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66
Q

OFF-center ganglion cell

A

decrease firing when light presented

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67
Q

ON-center bipolar cells

A

activated by light

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68
Q

OFF-center bipolar cells

A

inhibited by light

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69
Q

how do ON-center and OFF-center neurons communication

A

ON-center communicate with ON-center and vice versa

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70
Q

how does glutamate impact bipolar cells

A

it can active or inhibit them depending on receptor expression

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71
Q

bipolar cells with AMPA receptor will be ____ by glutamate because…

A

activated…. cation channels allow Na+ to flow into cell –> depolarization –
take away activation = inhibition

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72
Q

bipolar cells with mGluRG receptors (metabotropic) _______ neuronal activity because

A

inhibit neuronal activity
take away inhibition –> activation

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73
Q

horizontal cells

A

surround inhibition - sharpen receptive fields by inhibiting surround photoreceptive cells

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74
Q

thalamus (LGN)

A

visual perception

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75
Q

midbrain (superior colliculus)

A

visual reflexes and eye movement

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76
Q

midbrain (pretectal area)

A

modulation of pupil size

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77
Q

hypothalamus (suprachiasmatic nucleus)

A

sleep cycle modulation

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78
Q

retinotopy

A

specific parts of visual field are “mapped onto” (represetned) in specific parts of retina and brain

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79
Q

superior colliculus does two things

A

visual tracking and reflexes

80
Q

visual tracking

A

eye movements that occur while following an object

81
Q

visual reflexes

A

activate neck muscles that reposition the head to orient to a stimulus

82
Q

sensorimotor structure

A

using sensory movement to fine tune movement

83
Q

pupillary reflex

A

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
Q

suprachiasmatic chiasm

A

part of hypothalamus (homeostasis) that uses light signals to modulate sleep-wake cycle

85
Q

pathway BRAIN

A

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
Q

decussation

A

axons crossed at midline

87
Q

partial decussation

A

some axons cross midline - some dontip

88
Q

ipsilateral

A

pathway stays on same side

89
Q

contralateral

A

pathway crossed midline

90
Q

info from visual field…

A

strikes both eyes except more peripheral monocular field

91
Q

axons leaving RGCs of nasal hemiretina will cross at…

A

optic chiasm

92
Q

most peripheral portion of visual field

A

is processed through nasal hemiretina (will decussate) of ipsilateral eye of ipsilateral eye

93
Q

from contralateral eye will strike…

A

temporal hemiretina

94
Q

binocular

A

both eyes can see most of visual field

95
Q

dorsal stream

A

“where” stim is in space

96
Q

ventral stream

A

“what” is the stim

97
Q

lesion in optic nerve

A

right optic nerve lesion = right peripheral (monocular) visual field loss and vice versa for left

98
Q

lesion in optic chiasm

A

pituitary tumor –> tunnel vision

99
Q

sound is produced by

A

variations in air pressure

100
Q

properties of sounds

A

are the same as properties of light

101
Q

frequency

A

(Hz) pitch

102
Q

amplitude

A

volume (Db)

103
Q

complexity

A

timbre

104
Q

attenuation reflex

A

muscles attached to ossicles can tighten bones of inner ear, affecting their ability to stimulate the oval window

105
Q

AR muscle 1

A

tensor tympani, innervated by trigeminal nerve

106
Q

trigeminal nerve

A

CN V; sensory to face

107
Q

AR muscle 2

A

stapedius, innervated by facial nerve

108
Q

facial nerve

A

CN VII; motor to face

109
Q

cranial nerves are

A

a collection of axons in the PNS; typically correspond to face and correspond to brain stem (nuclei/cell bodies are in brain stem)

110
Q

outer/external ear

A

collect sound wave: pinna/auricle (ear) –> external auditory canal –> tympanic membrane (eardrum)

111
Q

how does the orientation of the pinna impact sound

A

because of how funnel is oriented - can hear front and to side better

112
Q

middle ear

A

transmit sound waves from eardrum to oval window

113
Q

oval window

A

border between middle and inner ear

114
Q

from eardrum to over window

A

eastachain tube and three ossicles

115
Q

eastachian tube

A

connect middle tube to nasal cavity for pressure and no build up

116
Q

three ossicles

A

malleus, incus, stapes

117
Q

PATHWAY FROM OUTER TO INNER

A

sound waves –> tympanic membrane –> malleus –> incus –> stapes –> oval window

118
Q

cochlea

A

3 main chambers and contains sensory receptors - the organ of corti

119
Q

3 main chambers of cochlea

A

scala vestibuli: perilymph
scala media: endolymph
scala tympani

120
Q

inner ear

A

transduce sound waves into electrical signal; when stapes hits oval window, causes movement of fluid in cochlea

121
Q

endolymph

A

high potassium, low sodium

122
Q

scala media

A

have hair cells that are anchored in basilar membrane (within organ of corti)

123
Q

hair cells

A

stereocilia and kinocilia are anchored in tectorial membrane (endolymph filled)

124
Q

conductive earing loss

A

problem in external/middle ear - signal cant get to cochlea

125
Q

sensorineural hearing loss

A

signal cant be sent to brain but is sent to cochlea

126
Q

rinne test

A

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
Q

mechotransduction

A

movement in fluid in cochlea causes basilar membrane to vibrate causing bending of stereocilia and kinocilia

128
Q

bending of stereocilia towards kinocilia

A

DEPOLARIZATION via opening of K+ channels

129
Q

tiplinks

A

bonding cilia physically together

130
Q

bending away from kinocilia

A

HYPERPOLARIZATION

131
Q

mechanoreceptors on end of cilia when bend

A

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
Q

vestibulocochlear nerve

A

CN VIII

133
Q

two branches of CV VIII

A

cochlear branch: coming from cochlea - hearing
vestibular branch: coming from vestibule - involving balance and eye movements

134
Q

two types of hair cells

A

inner and outer

135
Q

inner hair cells

A

provide most output from cochlea (can’t lose them)

136
Q

outer hair cells

A

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
Q

PATHWAY IN CNS

A

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
Q

stimulus intensity

A

louder sound –> greater amplitude of basilar membrane –> stronger activation of hair cells –> INCREASED FIRING RATES

139
Q

tonotopy

A

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
Q

interaural time delay

A

sound infront reaches each area at same time; as it goes closer to one side there is more of a difference between ears

141
Q

vestibular system

A

has otolith organs and semicircular canals

142
Q

otolith organs

A

utricle and saccula: detect changes of head angle and linear acceleration

143
Q

semicircular canals

A

detect head movement, angular acceleration

144
Q

special sense

A

have special sensory organs dedicated to them, sensory info reaches CNS via CN

145
Q

skin (and muscles, joints, organs)

A

sensory organs for somatosensation

146
Q

info reaches CNS

A

via peripheral nerve (unless info from face)

147
Q

somatosensation

A

sensation of the body - soma = body in greek

148
Q

proprioception

A

position of body in space - mediated by sensory receptors in muscles, joints and skin (can be conscious or unconscious)

149
Q

exteroception

A

sense of direct interaction with world as it impacts body: touch and temperature/pain

150
Q

interception

A

sensation associated with organs, important for automatic regulation

151
Q

nociception

A

pain/temperature

152
Q

conscious

A

skin –> spinal cord –> brainstem –> thalamus –> primary somatosensory cortex

153
Q

unconscious

A

skin –> spinal cord –> brainstem –> cerebellum

154
Q

spinal cord anatomy

A

gray matter on inside - dorsal and ventral horn - contains primarily cell bodies
white matter on outside - myelinated axons (tracts)

155
Q

ascend to brain

A

sensory

156
Q

descend

A

motor

157
Q

dorsal root/horn

A

incoming sensory info from periphery

158
Q

ventral root/horn

A

outgoing moto info to periphery

159
Q

spinal nerves will eventually become

A

peripheral nerves

160
Q

segmental organization of spinal cord

A

different “levels” of spinal cord

161
Q

cervical

A

upper extremity

162
Q

troasic

A

trunk

163
Q

lumbar and saural

A

lower extremity

164
Q

dermatume

A

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
Q

dorsal root ganglion cells

A

carry somatosensory info from body into spinal cord via dorsal root

166
Q

pseudo-unipolar morphology

A

all somatosensory info carried to CNS via DRG cells

167
Q

all afferent/somatosensory info enters thru

A

dorsal root and either synapses in grey matter or medulla

168
Q

different fiber types carry different modalities of somatosensory info relate to

A

size, myelination status, function

169
Q

axon size

A

decrease axial resistance

170
Q

myelination state

A

increase membrane resistence

171
Q

fiber types

A

1a, 1b, A-beta, A-delta, c-fibers

172
Q

1a

A

largest axonal diameter, myelinated, carries info on muscle stretch from muscle spindle - proprioception

173
Q

1b

A

second largest diameter, myelinated, carries info on force of muscle contraction from golgi tendon organ - proprioception

174
Q

A-beta

A

middle axonal diameter, myelinated, carries info from a variety of mechanoreceptors in skin and joints - exteroception (minus pain and temp)

175
Q

A-delta

A

second smallest axonal diameter, myelinated, sharp, localized pain - pain and temp and free nerve endings

176
Q

c-fibers

A

smallest axonal diameter, unmyelinated, dull, burning pain - pain and temp and free nerve endings

177
Q

trigeminal nerve (CN V)

A

carries somatosensory info from face and contains neurons that are analogous to DRG cells

178
Q

mechanoreceptors are

A

activated by physical distortion

179
Q

receptor cell

A

connective tissue/protein receptor (both mechanoreceptors) –> DRG cell

180
Q

muscle spindle

A

detects muscle stretch –> main receptor for proprioception; activated when muscle stretches

181
Q

golgi tendon organ

A

detects force of muscle contraction

182
Q

mechanoreceptor affects DRG cell’s

A

receptive field and adaptive field

183
Q

receptive field

A

how much area is covered by this DRG cell

184
Q

adaptive field

A

if apply prolonged stim, how many aps will be fired/will it stop/adapt

185
Q

bare/free nerve endings

A

pain and touch

186
Q

dorsal spinocerebellar pathway

A

unconscious proprioception for lower extremity –> allows motor system to use sensory info to coordinate movement
cerebellum uses unconscious proprioceptive info to coordinate movement

187
Q

dorsal spinocerebellar pathway PATHWAY

A

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
Q

dorsal column pathway

A

conscious proprioception and exteroception for entire body: fine touch, vibration, etc.

189
Q

dorsal column pathway PATHWAY

A

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
Q

anterolateral pathway

A

pain and temperature

191
Q

anterolateral pathway PATHWAY

A

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
Q

somatotopy in cortex

A

particular parts of body “map” to particular parts of primary somatosensory cortex

193
Q

somatosensory homunculus

A

face and arm region map to more lateral parts to cortex
legs and urogenital region map to most medial part of cortex

194
Q

body info carried to

A

spinal cord by DRG neurons and transmitted to VPL thalamus

195
Q

face info carried to

A

brainstem by CN V and transmitted to VPM thalamus