week 6B - somatosenstion Flashcards
what is tactile acuity?
ability to distinguish between 2 poitns
small recpetive fields permit ___ of spatial detail
high resolution
what is the 2 point discrimination test?
prong distances provide two point threshold - minimum seperation needed etween 2 points to eprceieve them as two units
What cutaneous mechanoreceptor would be most likely
responsible for tactile acuity?
A) Merkel
B) Pacinian
C) Meissner
D) Ruffini
merkel
tactile acuity thresholds are determind by?
merkel receptores (SA 1)
what is the grating acuity test
placing a grooved stimulus on the skin and asking the
participant to indicate the orientation of the grating
what 3 factors deteermine tactile acuity?
size of receptive field, density of recepptors, representation within somatosensory cortex
the tipe of the finger has higher concentrations of ___ and ___ receptors
SAI and FAI (merkel and meissner)
___ and ___ recptores are more equally distrubuted around the body
SA2 and FA2. - ruffini and pacinian
___ are hte most desnely packed in the fingertips
merkel receptores
body surfaces that have higher desnity of recptors and small recptive fields have a ____ 2 point discrimination thrshold
lower
what does a lower 2 point discrimination threshold mean
lower threshold indicates that the person has better sensory acuity, meaning they can feel and differentiate between two stimuli when they are closer together. This ability is often better in areas like the fingertips or lips, where there is a higher density of sensory receptors.
why might you want a lower 2 point dsicirmination threshold on the fingers? face? toes ?
fingers - accurate gasping movements
face - protective
toes - balance, injury
sensation occurs hen___ whereas perception occurs when___
peripheral recptors are stimulated
brain interprets sensory stimualtion
the thalamus does what?
relays info from sensory recpetors to areas of cortex
True or false/ peripherphal nerve fibers travel indiviually to the spinal chord.
FALSE - travel in bundles
what are the 2 major somatosensory pathways
Medial lemniscal
- large fibers carry proprioceptive and touch info
spinothalmic
- smlall fibers carry temp and pain info
- cross over oppsit side of body and synapse in thalamus then onto SS cortex
the medial leminsal pathway consists of ____ fibers
large
the medial lemniscal pathway carys info on ___ and__
propriocpetion and tocuh
the spinothalmic pathway carrys info on ___ and __
temp and pain
somatosensory info ascends in ___ tracs in the __
afferent tracts in spial chord
where does somatosensoty info project to?
primary SS and parietal cortex
what love is the primary SS cortex found in?
parietal lobe
the primary SS cortex is located in ___ of crotex called the __
ridge - aclled teh post-central gyrus
amount of cortical tissue devoted to each body surface is porpotional to ___ and represent by the ___
sensitivity of that part
rep by SS homonculous
what areas are more senstiieve tehn otehr parts of body
lips, tongeu, hands, feet and genitals
Across species the SS cortex map fo body refelcts wat>
density of peripheral recpetors . rep within SS + functional releeane
tactile acuity ___ and threshold ____ from index to pinky
tactile acuity decrease, threshold increase
what happens to the desnity of merkelr ecptors actoss fingers - from index to pinky
merkel receptor density stays the same - howevre tactile acuit decrease(theshold increases)
what finger hasth largest rep in the SS cortex
index
Nigel and Sasha visit the clinic to have their tactile acuity tested. Sasha’s tactile acuity thresholds are much lower than Nigel’s.
A) What factors may determine whether Sasha’s Tactile Acuity is better than Nigel’s?
sasha may have smaller receptive field, greater density of receptors + greater rep in the SS cortex
B) What cutaneous mechanoreceptor is most likely important for tactile acuity performance?
merkel cells - small recpetive field with multiple hostpots
