Fitzayyy Flashcards
somatosensation
process that conveys info regrind body and itxn with environment
- mechanoreception
- thermosensation
- nociception
transduction channel is a member of
transient receptor potential superfamily of ion channels eg: thermoreceptors adapt rapidly to temps mechanoreceptors repsond to deormations nocicptors respond to \_\_\_\_\_
nociceptors/TRPV1 opens/responds to
heat
protons
vanillinoids
potentiated by prostaglandins = sensitiziation
perception of pain is not simply due to activation of nociceptors, but is the outcome of
modulation of both nociceptive and non-nociceptive inputs
gate theory of pain
inhibitory interneurons regulate the transmission of ascending nociceptive information at the level of the second order neuron, allowing modulation of the signal
explains phantom limb pain
success of TENS treatment
opioids
steady pressure and stretch receptors
flutter and vibration receptors
Merkel and Ruffini
slowly adapting
Meissner’s corpuscles and Pacinian corpuscles
rapidly adapting
thermoreception: stimulus receptor location receptive field adaptation
(high acuity, well localized, rapid adapt) cold = menthol, warm = capsaicin free nerve ending superficial small RF rapid adapt
*direcly coupled to ion channel/no 2nd mess)
nociception: stimulus receptor location receptive field adaptation
(poor acuity, slow adapt) thermal = heat, mechanical, polymodal chemical = capsaicin, protons free nerve endings superifical small/rapid, large/slow, large/slow
think thermoreceptors…
Receptor proteins depend on….
nociceptive or no?
stimulus type, not the anatomy
compounds that sensitize the receptor protein, decrease the threshold for activating channel
sensitization causes
5-HT, ATP, PGs, bradykinin
hyperalgesia - increased pain perception from painful stimulus
allodynia - pain from stimulus that doesn’t normally cause pain
TRP channels
nonspecific cation channels
think TRPV1 and nociception**
how test acuity/how well pain is localized
point localaiton vs 2 point discrimination
physical distance where can perceive two stimuli versus one
C fibers
unmyelinated DULL ACHY PAIN low conduction velocity small diameter mechanoreception, thermoreception, SLOW PAIN
Abeta fibers
myelinated large diameter high conduction velocity MECHANORECEPTION ONLY* OW!
Adelta fibers
myelinated
medium diameter
medium conduction velocity
mechanoreception, termoreception, FAST PAIN
3 types of pain
- ACUTE NOCICEPTIVE: fast (sharp, pricking), well localized, Abeta OR slow (achy, dull) C fibers, not well localized
- INFLAMMATORY PAIN: damage or sensitization to receptor or adjacnet damaged cells
- NEUROPATHIC PAIN: peripheral or central REORGANIZATION of pathway so don’t need a nociceptive stimulus to perceive pain
referred pain
activation of nociceptors in viscera = perceived as somatosensory problem
so TWO PATHAWYS GOING TO THE BRAIN
brain doesn’t know how to interpret
nociception is _____
pain is the _____
sensation
perception
transduction
stimulus energy (electromagnetic, mechanical or chemical) converted into electrical potentials interpreted by nervous system
- stimulus
- accessory strux
- receptor with transducer protein**ESSENTIAL STEP
- seomteims: snd mess
- ion channels open or close
- membrane pot change = receptor potential***
- sometimes NT release on 2nd cell
- AP generation
receptor potential is a _______ to a stimulus
graded response
adequate stimulus
type* of energy that a receptor responds to under normal conditions
stimulus intensity is encoded int wo ways:
- frequency coding (firing rate increases with increased intensity)
- population coding (number 1* afferents increases = RECRUITMENT)
adaptation
response of a receptor to constant stimulus declines over time
if change in receptor potential occurs:
SLOW = TONIC
RAPIDLY = PHASIC
acuity
ability to localize a stimulus
determined by receptive fields size and receptor density
lateral inhibition
application of a stimulus to center of the RF excites a central neuron, but a stimulus applied near the edge inhibits it
= shuts off adjacent neurons
= just because detected in receptor, doesn’t mean you will perceive it
sensory unit
sensory afferent 1* and receptors that define its receptor field
TENS: gate theory
an opportunity to shut down the pain system
under normal circumstances, not having pain because
- no stimulus
2. second order inhibitory neuron
by stimulating ______ can shut down the pain pathway/gate to pain
stimulating mechanoreceptors*** reactive the inhibitory interneuron to close gate again
inhibitory interneurons of gate of pain are releasing
glycine
external and middle ears stimulation
sound
job of _____ to deal with complex sounds
cochlea
complex sounds can be deconstructed into a series of sin and cosin waves into component frequencies
cochlea is linear or nonlinear
nonlinear - get more freq out than put in
external ear/pinna susceptible to shearing upon anterior force
cauliflower ear:
force forward shears cartilage of bone > hematoma > stimulation more cartilage growth
4 nerves innervate external ear
greater auricular less occipital (both off cervical plexus) auricular branch of CN X (can envoke fainting from ear) auriculotemporal branch of V3
cause of conductive hearing loss
impaction of cerumen into TM
two types glands *unique to EAM
- ceruminous
2. sebaceous of hair follicle
tympanic membrane
deepest point: umbo
pars flaccid doesn’t move
4 separate tissue layers: EAC, epithelium, connective distress, endothelium, middle ear
TM innervated by
- external surface: anterior and posterior auriculotemporal of V
- internal surface: tempering branch of IX glossopharyngeal
sense cold, pain, touch
vibration of TM causes
malleus and incus to pivot > stapes footplate vibration at the oval window
why is air conduction better than bone conduction
the gain in pressure due to the actions of the ossicles from air sounds prevents some of the energy loss inherent in an air/fluid transition
middle ear function
determines what IE will hear
minimizes loss of energy that occurs at air/water interface
amplifies force by
1. TM much larger than OW
2. malleus makes lever situation > lever ratio
3. TM buckles: force concentrated at jumbo
*anything that affects this matching will cause CONDUCTIVE HEARING LOSS
mass vs. stiffness
mass: heavy, can’t vibrate quickly > transmits low
stiffness: think elasticity, volume of air cavity > transmits high
*every substance has an internal impedance that affects its resonance
normal hearing range
100Hz - 20KHz
hearing loss starts at
25 dBSL (relative)
conductive HL
air conduction affected
two labyrinths in inner ear
- bony: contains perilymph
2. membranous: contains endolymph
vestibular/ossesous labyrinth projections
- semicircular (3)
- cochlea (spiral)
- vestibular aquaduct
- cochlear aquaduct (connects perilymph to CSF)
membranous labyrinth
completely enclosed
- cochlear duct: scala media (core of spiral)
- saccule (has macula)
- utricle (has macula)
- endolymphatic duct (ends in endolymphatic sac)
- ant, post, and lat semicircular canals
receptive areas (where hair cells are)
6 total in each ear
- organ of Corti (HEARING)
- maculae = otolith organs (saccule and utricle) (BALANCE)
- cristae ampullaris = semicurcular canals (BALANCE)
inner ear innervation
CN VIII
sensory AFF to brainstem from HC (esp type I)
motor EFF from brainstem to HC (esp type II)
4 branches:
- auditory branch (cochlea)
- superior vestibular (utricle and SCs)
- inferior (saccule)
- posterior (posterior canal)
hair cell transduction
- fxn as mechanoreceptors: have steriocilia on apical surface that have transduction channels that O and C to change receptor potential (with stretch activated channels)
type I hair cells
type II hair cells
“true” sensory receptors
90% AFF
EFF go to dendrites of AFF
motor/contractile cell
10% AFF
each 1* many II HC
large, very secure EFF synapse
inner ear transduction is DIRECTIONAL:
displacement toward the tallest stereociliar (positive deflection) results in DEPOLARIZATION
adaptation definition
adaptation motor
decrease in response of receptor to a continuous stimulus
move SC towards tallest, the anchoring protein on tall slips down, decreases tension, causes channel to close = keeps hyper polarization possible
motor: keeps tension at proper point for response (channel open)
semicircular canals detect ______
otolith organs detect ______
SCs detect head rotation (angular acceleration)
OOs detect gravity (linear accleration)
cilia type only in vestibular system
kinocilium
adjacent to tallest steriocilia
move head, then >
head rotates (HC move) > fluid doesn’t move (inertia) > steriocilia deflect (dep or hyp)
head reaches constant velocity > cupula catches up
steriocilia aren’t deflecting > no signal
head stops > fluid and cupola keep moving > steriocilia in opposite direction
otolith organs responding to gravity
S: away from midline, horizontal
U: toward midline, vertical
*both otoliths responding in all orientations, stimulate one more than the other
otoconia
CaCO3 crystals sitting on top of steriocilia to deflect to gravity
base of cochlea
apex of cochlea
base encodes high freq
apex encodes low freq
3 tubes/scalae
vestibuli and tympani have perilymph
scala media has endolymph
two membranes cochlear
BASILAR divides ST from SM
VESTIBULAR divides SV from SM
spiral ganglion/auditory nerve is
in the middle of the bony modiolus
scala media
- BM vibrates
- SG neuron AFF to inner and outer HC
- stria vascularis generates endolymph and endochoclear potential (K+)
shearing force that causes steriocilia to move
BM vibrates and Tectorial membrane doesn’t vibrate > creates shearing force
dieter cell
underneath OHC contributes to reticular lamine (stability when OHC contracts)
pressure wave induces
vibration (starts in base > peaks at some point)
sensoriunrual HL
as age, damage to base first = high frequency HL first
passive properties
base: elastic, few supporting cells LOW MASS
apex: floppy, lots of supporting cells
*EACH PLACE HAS SPECIFIC COMBO OF MASS AND STIFFNESS > SPECIFIC RESONANCE FREQ
OHC contraction >
increase AMP of BM movement > OHCs contract > mechanical transduction > acoustic energy > resonance vibe at particular spot > BM vibrates > OHCs contract
also signal to the brain when BM vibrates: APs generated by IHCs
POSITIVE FEEBACK LOOP
OAE
otoacoustic emissions: sound coming from ear, generated by OHC
stria vascularis
produces endlymph (high K+) and the endocohlear potential (+80mV)
auditory pathways
HCs in cochlea > auditory nerve > cochlear nuclei in brainstem > trapezoid body > superior olivary complex > lateral lemniscus > inferior colliculus > brachium of inferior colliculus > medial geniculate nucleus > internal capsule > primary auidotyr cortex (superior temporal gyrus) = perception
acoustic reflex
HCs in cochlea > spiral ganglion/auditory nerve > cochlear nuclei > trapezoid body > superior olivary complex >
- EFF to HCs in cochlea
- trigeminal motor nucleus > V3 > tensor tympani in ME
facial motor nucleus > VII > stapedius ME
*STIFFEN, HARDEN TO SOUND = DECREASED SOUND TRANSMISSION
extensive ______ connections of auditory system
BILATERAL
vestibular pathways
HCs in SC canals and otolith organs > vesibular ganglion/vesibular nerve > vestibular nuclei >
i. medial lemniscus > ventroposterior nucleus of thalamus > internal capsule > vestibular cortex = PERCEPTION
ii. lateral vestibulospinal tract (LVST) > limb and trunk
medial vestibulospinal tract (MVST) > upper back and neck = VESTIBULOSPINAL REFLEXES
iii. inferior cerebellar peduncle > vestibulo-cerebellum/flocculonodular lobe = VESTIBULOCEREBELLAR REFLEXES
iv. medial longitudinal fasciulus (MLF) > 3 motor nuclei:
oculomotor nucleus > CN III > sup, med, inf rectus
abducens nucleus > CN VI > lateral rectus
trochlear nucleus > CN IV > superior oblique
= VESTIBULO-OCULAR REFLEX (VOR)
acoustic neuroma impacts
IAM
vestibular CN VIII and facial CN VII
damages acoustic N and facial N and labyrinthine artery > hair cell damage
vestibulospinal tract is ______ in cervical SC
ventral column
vestibular nuclei found dorsal in _____ section
solitary nuclei and tract found dorsal in _____ section
MLF found _____ in _____ section
cochlear nucleus found dorsal and _____ in _____ section
medulla section
medulla section
MLF found medially in medulla section
dorsal and lateral in medulla section
superior vestibular nucleus (SVN) found in ______ in _____ section
superior olivary nucleus (SON) found _____ in _____ section
abducens nucleus found _____ in _____ section
corticospinal tracts found _____ in _____ section
lateral lemniscus is found _____ in _____ section
SVN found in MCP of pons section
SON medial WHITE SPOT in pons
nCN VI medial in pons
in potato of pons
lateral in pons
inferior colliculus found in _____ section
SCP decussation found in _____ section
cerebral crus found in _____ section
midbrain section
medial geniculate body found in _____ section
rostral midbrain section
auditory brainstem responses (ABRs)
evolved potential response
estimate of inner ear function and if central pathway fun is correct
peak and valleys: response of nerve
eg: stimulation > AN > TB trapezoid body > BIC brachium inferior colliculus > 1* aud cortex
ability to localize sound tested by
Weber
superior olivary nucleus can compare ____ and ___ of both sides ability to localize sound
compares timing and intensity
if alter timing in one ear, can’t process where sound is from - change in weber test (sound localizes to one ear)
Weber findings
abnormal: sound localizes to one ear
CONDUCTIVE hearing loss, SOUND travels to DAMAGED EAR
SENSORINEURAL hearing loss, SOUND travels to GOOD EAR
LVST lateral vestibulospinal tract
MVST medial vestibulospinal tract
AFF: entire labyrinth MOTION AND GRAVITY
lateral vestibular nucleus
POSTURAL CHANGES to compensate for tillts
adjustment of PROXIMAL LIMB AND TRUNK
(contracts extensor muscles, indirect relaxation of flexor muscles)
EFF: IPSILATERAL, excitatory
AFF: SC canals MOTION
medial vestibular nucleus
STABILIZE HEAD POSITION WHEN WALK
relaxation of muscles of upper back and neck
EFF: BILATERAL, “more complicated than ex and in”
impt clinical test for brain activity/brain dead
VOR
no “dolls eyes” movement = brain dead
VOR
move head in one direction, eyes move in other direction
to compensate for head motion
turn head left > left DEPOLARIZATION > vestibular ganglion > vestibular nuclei > L excitation > IPSILATERAL CN III medial rectus and CONTRALATERAL CN VI lateral rectus
hyperpol and inhibition of others
nystagmus
competition between VOR and cortex to where head and eyes should be. defect in vestibular system when spontaneous nystagmus
COWS; name nystagmus by FAST SACCADE: “beating”
COWS
cold water: opposite nystagmus (cold water in left ear, right nystagmus)
warm water: same nystagmus (warm water in left ear, left nystagmus
nystagmus and lesion locations
lesion in CORTEX: SACCADE eliminated
lesion in BRAINSTEM: NO VOR or SACCADE
conductive HL damage
sensorineural HL damage
central auditory processing disorders damage
external or middle ear
HC or auditory N or cochlear
“cocktail party” hearing deficit in CNS, inferior colliculus
profound worsening HL at ____ Hz
80Hz
normal audiogram
air conduction through ME gives lower thresholds than bone. AC > BC
conductive HL
sensorineural HL
bone thresholds normal, air thresholds much higher
(need more sound)
WORSE AIR CONDUCTION THAN BONE CONDUCTION
HL for both AC and BC
bone and air thresholds much higher (especially in higher Hz)
Rinne tests for
Weber tests for
conductive loss
lateralization of hearing or HL
unilateral SENSORY loss: localization to normal ear
unilateral CONDUCTIVE loss: localization to affected side
tympanometry test
measures ME pressure fluid in ME TM perforation ossicular chain disruption potency of ventilation tube
acoustic reflex test
apply sound and conduct tympanometry test
*HL required to evoke acoustic reflex = middle ear compliance
FACIAL NERVE FXN
audiograms test
OAE: ME fxn, COCHLEAR (OHC) FXN
ABR (auditory brainstem response): ME fxn, IE and auditory nerev fxn, AUDITORY PATHWAY FUNCTION
intrafusal muscle fibers
NON-contractile
1* (Ia) afferent fibers
2* (II)
INNERVATED BY GAMMA MNs
extrafusal muscle fibers innverated by
alpha MNs
______ responsible for the stretch reflex.
Muscle spindles
stretch reflex 5 steps
- muscle stretches
- depolarization in spindle AFFERENT
- activation of alpha nd gamma MNs
- contraction of extrfusal and intrafusal muscle fibers
- maintains tension in spindle to allow it to connive to be response
inverse stretch reflex
increased activity of inhibitory interneuron > decrease alpha MN activity > RELAX
flaccid paralysis
spastic paralysis
eliminate alpha MNs
overactive gamma MNs
reflex arc
- sensory receptor
- 1* afferent neuron
- 1-3 CNS synapses
- MN
- muscles
recurrent inhibition
afferent neuron or mN shuts itself off
absence of descending control of gamma MNs >
clasp knife reflex
Perception: complex processing types
- series processing (labelled line/series carried to cortex)
- parallel processing (divergence)
- convergence (within and across modality/gate theory of pain: mechano and noci to SC)
- descending info down to receptor level
“what you see is not what you get”
selective attention
cortex decides what it wants to perceive
posterior parietal selective attention?
ganglion cells and lateral inhibition by ______
horizontal and amercing cells are responsible for lateral inhibition
result > ganglion cells have increased response to contrast; generate a definitive response
key step to integrate PRs response and generate APs in ganglion cells:
response of BIPOLAR CELLS
some don’t chang signal, some flip signal so is off, depends = complex ganglion cell response
ganglion cells
primary visual cortex
on and off cells
orientation
then orientation and motion
= DORSAL STREAM: WHERE
visual cortex physiology:
1st dimension
2nd dimension
3rd dimension
1st: OCULAR DOMINANCE > depth perception
2nd: ORIENTATION: edges and motion
3rd: COLOR in “blob” regions
_____ is overrepresented within primary visual cortex input = ocular dominance
fovea
strabismus
muscle imbalance results in misalignment of visual axes of two eyes > causes DIPLOPIA
amblyopia
suppresses info from weaker one eye (cortex coping), so decreased visual acuity
permanent
80% of ganglion cells encode _____ (color perception)
encode L/M wave: red green differences
difference in acuity depends on
contribution of cone types because RFs are different sizes
luminescence (wavelengths)
long and medium (L + M) wavelengths, red and green codes encoding = CONTRAST
outputs from visual cortex
dorsal and ventral streams
ventral stream: “WHAT” encodes COLOR AND FORM
dorsal stream: “WHERE” encodes MOTION AND DEPTH PERCEPTION
corticoacromotopsia
can’t see color or id things
ventral stream/color and form issue
ideomotor apraxia
can’t execute movements dependent on site
dorsal stream/motion and depth perception issue
language processing (general process)
- comprehension (input)
LISTENING (starts in auditory)/READING (starts in visual) - interpretation of language
- expression (output)
SPEAKING (vocal apparatus muscles)/WRITING (hand muscles)
what defines a language
grammar (symbols)
syntax (contex)
prosody (conveys meaning)
primary language pathway
input from primary visual and auditory cortex > LANGUAGE COMPREHENSION in Wernicke’s area in posterior temporal lobe > arcuate fasciculus > MEANINGFUL LANGUAGE FORMED in Broca’s area in posterior inferior frontal lobe > primary motor cortex > voluntary muscles > speech
Gershwind’s territory
receives input from primary visual and auditory cortex > RECOGNIZE AND LABELS ITEMS > synapse on Wernicke and Broca’s areas
not developed until 5/6 years old (so can read)
Lateralization
LEFT (dominant) cortex: RIGHT VISUAL FIELD processing
RIGHT cortex: LEFT VISUAL FIELD processing
= lateralization through corpus collosum
another lateralization example
PROSODY (emotion of speech) COMPREHENSION and INTERPRETATION in RIGHT cortex > thru corpus colosseum (?) > LEFT cortex: WRITING and SPEECH COMPREHENSION > L + R 1* motor cortices > output
handedness stats
90% right handed, 10% left handed
LANGUAGE localized in L cortex and
EMOTIONAL CONTENT in R cortex:
true in 95% of RH people and 60% of LH people
(of 20% bilateral, 20% are R cortex dominant)
vocalization = tonal qualities of speech (steps)
- airstream from lungs
- vibration of vocal folds
- filtering by vocal tract (vowels/shape of vocal tracts and consonants is opening and closing folds)
- output sound
phonomes
speech sounds
200 phonomes > syllable > words > sentences
10,000 words in active (average) vocabulary
aphagias definition/general types
speech disorders
impaired language without affecting other cognitive fxns
impairment in ability to sue or comprehend words
- FLUENT can generate words, can’t comprehend
- NON-FLUENT can comprehend, can’t generate words
aphasias/dyphasias (4)
- RECEPTIVE dysphasia:
WERNICKES
severe deficit in auditory and written COMPREHENSION
FLUENT (many words, but is nonsense) - CONDUCTION dysphasia:
ARCUATE FASCICULUS
good comprehension, pauses and gaps to figure out words
FLUENT
GERSHWIND area
inability to COME UP WITH CORRECT WORDS
- EXPRESSIVE dysphasia:
BROCA’S
inability to GENERATE MOTOR CONTROL PATTERN
know what want to say but can’t, extremely frustrating
NON-FLUENT - GLOBAL aphasia
profound deficits in both COMPREHENSION and EXPRESSION
entire language pathway disrupted/large areas of damage
aprosody
inability to COMPREHEND or EXPRESS MEANING of EMOTIONAL EMPHASIS*
apraxia of speech
difficulty initating and executing voluntary movement patterns necessary to produce speech when NO PARAYLSIS/WEAKOF SPEECH MUSCLES
= PLANNING/PROGRAMMING PROBLEM
can generate words, can’t output
kids
dysarthrias
disruption of motor/musclar control due to lesions in CNS/PNS
CNS -X-> muscle
= neuromotor disorder
