Exteroception Flashcards
Lemniscal system conveys ___ info
info about fine, discriminative touch, limb proprioception
Pacinian corpuscles
Adaptation
receptor field
type of detection
location
Adaptation = fast
receptor field = large
type of detection = vibration
location = deep in dermis
Ruffini endings
Adaptation
receptor field
type of detection
location
Adaptation = slow
receptor field = large
type of detection = stretch
location = deep in dermis
Meissner’s corpusces
Adaptation
receptor field
type of detection
location
Adaptation = fast
receptor field = small
type of detection = tactile sense
location = superficial
merkel’s disc
Adaptation
receptor field
type of detection
location
Adaptation = slow
receptor field = small
type of detection = steady touch
location = superficial
define adaptation
how quickly recepotr responds to changes in frequency of stim
fast adapting receptors produce ___
slow adapting receptors are __
all or nothing response to stim (AP fired each time stim and cell quickly return to normal regardless of intensity)
slower to recover so AP continue to be fired at incr freq with stim (don’t adapt)
so incr freq of AP with incr intensity
usefulness of
fast adaptation vs slow
fast = impt for sensing textures and vibrations
slow = correlate with intensity of stim (stretch = Ruffini and pressure = Merkel’s(
receptive field define
deep vs superficial
area over which receptor stim
deep = large field and respond to wide area
superficial = finer tactile discrim
flow info for fine touch sensation and propioception below head
info carried via medial lemniscal path
1) mechanoreceptor on 1’ neuron in periphery have cell body in DRG
2) send process thru dorsal horn
3) ascend in cord in dorsal column ipsil (fasciculus cun vs gracilis)
4) synapse on to dorsal column nuclei (cun or fascic) in caudal medulla
5) synapse on VPL nucleus of thalam
6) synapse on to primary somatosensory area
flow info for fine touch sensation and propioception from the head
via trigeminal nerve lemniscal pathway
1) mechanoreceptor on 1’ neuron from head have cell body in trigeminal ganglion (pons level)
2) extend process into dorsal pons
3) synapse on to second order neuron in principal nucleus of dorsal pons
4) cross midline and join medial lemniscus
5) synapse on VPM of thalamus
6) enter face area of somatosensory
define somatotopy
organization of body map on cortex for carry and receive info from particular areas of body
what does it mean when some areas of map are larger than others
more extensive innervation (hands and feet)
different areas of somatosensory cortex receive or relay info on __-
different types of sensation
how is there parallel maps?
each area of cortex repeats somatotopic maps so multiple parallel maps each correspond to distinct sensory function (touch, propioception)
also comm with motor cortex
brodmann area 3a = 3b = 1 = 2=
3a = deep tissue muscle stretch receptor (propioception) 3b = skin slow and fast adapt receptor (touch)
1 = orientation and direction
2= shape, orientation, direction
2b = simple touch
2a = proprioception (feeling stretch/relax muscle)
also send axon from 2, 1 to 3
4 = motor control
2, 1, 3 = somatosensory
describe cortical barrels/columns
barrel = vertical slice that contains neurons all of diff groups (differ in modality, receptive field location)
functions of different layers of cortical barrel
1 2 3 4 5 6
1 = neurons and tufts of dendrites
2 = project to ipsil secondary somatosensory area and contralateral primary somatosensory area, posterior parietal cortex, motor cortex
3 = same as 2, also has inhibitory interneuron
4 = receive neurons from thalamus
5 = send neuron to basal ganglia, brain stem, spinal cord
6 = send neuron to thalamus
guillan barre
CSF content?
Treatment?
peripheral demyelination
loss of vibration and touch bilaterally in glove and stocking configuration
weak in distal extrem
little change in pinprick
elevated CSF proteins
plasmapharesis; intubation and artificial ventilation
