first sensory responses observed in fetus - CORRECT ANSWER- ✔✔responses by 8 weeks
cortisol and endorphin responses seen early
mechanoreceptors - CORRECT ANSWER- ✔✔responsive to pressure, stretching, vibration
temperature receptors - CORRECT ANSWER- ✔✔responsive to heat and cold
chemical receptors - CORRECT ANSWER- ✔✔responsive to inflammation, itch, tissue
damage
merkel receptors (with tactile disks) - CORRECT ANSWER- ✔✔superficial layers, small
receptive fields, slow adapting fires as long as the stimulus is applied
fine detail of contact
tactile disk goes up and gets signal from merkel cells
meissner corpuscles - CORRECT ANSWER- ✔✔superficial layers, small receptive fields,
FAST adapting, fires to transitions of the stimulus (at onset and at offset)
control of grip pressure
,ruffini cylinders - CORRECT ANSWER- ✔✔deeper layers, larger receptive fields, slow
adapting, fires continuously with application of stimulus (SUSTAINED)
skin stretching
pacinian corpuscles - CORRECT ANSWER- ✔✔deeper layers of glaborous skin, large
receptive fields, FAST adapting, fires with transitions of the stimulus.
wrappings allow vibration to pass through to stimulate the nerve fiber but sustained pressure
is not registered
sensing vibration
vibrations on palms and soles of feet important bc vibration can create grip on the floor
two-point discrimination test - CORRECT ANSWER- ✔✔judgement of whether one was
touched at one location or two
ex: one/two pins on a palm
"spatial resolution" and size of receptive fields of neurons at that skin location
grating discrimination test - CORRECT ANSWER- ✔✔subject judges at what orientation the
bars of the grating are tilted
Merkel disks can deliver info about stimulus whereas pacininan corpuscles are not providing
a useful signal
fingers have... - CORRECT ANSWER- ✔✔SMALL receptive fields. low threshold for two-
point discrimination (around 2 mm)
smallest is about the size of the fingertip
,neurons on torso have... - CORRECT ANSWER- ✔✔LARGE receptive fields, high threshold
for two-point discrimination
basket endings (hair receptors) - CORRECT ANSWER- ✔✔an experiment was done to test if
these can be treated like fibers that provide sensory information
cut the tip of the hair off and stick it somewhere else --> skin still senses it.
so...basket endings may be a motor fiber that controls sweating or maybe they lift hair up (in
insulation or aggression)
_____ is the primary stimulus for itch - CORRECT ANSWER- ✔✔histamine
released in response to various agents that induce tissue inflammation
skin and pleasure - CORRECT ANSWER- ✔✔Researchers are beginning to classify slow
responding (C fiber) tactile input,
especially from hairy skin, as having an affective (emotional) role rather than an informative
one. They go so far as to suggest that this submodality of sensory
information is to provide pleasure and comfort from social contact.
krause end bulbs - CORRECT ANSWER- ✔✔perceive cold
free nerve endings - CORRECT ANSWER- ✔✔fill the skin with fine, unmyelinated fibers
, ______
von frey said only places that generated pain were filled with free nerve endings. took a pig
bristle, dipped in hot water, put on cornea --> pain. did the same with cold water --> pain.
concluded that he thought that the cornea only had free nerve endings, so free nerve endings
are pain receptors (he was wrong)
_____
skin of ear lobe only has free nerve endings, but it can respond to several submodalities
(TEMPORAL CODE? NOPE) --> maybe PATTERN THEORY
temporal code - CORRECT ANSWER- ✔✔spacing among successive spikes in AP would
provide a message with each stimulus producing a unique temporal pattern
pattern theory - CORRECT ANSWER- ✔✔cross-comparison of signals to derive an
interpretation of the nature of the stimulus --> inferring the perception from the pattern of
mixed responses being delivered
warm and cold fibers - CORRECT ANSWER- ✔✔have very small receptive fields with little
or no overlap among neighbouring fields
fire at a particular frequency for constant skin temperatures and provide a signal if there's a
skin temperature change
cold: responds to menthol
warm: responds to capsaicin
cold fibers start firing again at very high temperatures during which warm fibers also fire -->
DANGER!
why do cold and warm fibers both fire at high temperatures? - CORRECT ANSWER-
✔✔this is dangerous
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