Exteroception

Question 1

Lemniscal system conveys ___ info

Answer 1

info about fine, discriminative touch, limb proprioception

Question 2

Pacinian corpuscles

Adaptation
receptor field
type of detection
location

Answer 2

Adaptation = fast
receptor field = large
type of detection = vibration
location = deep in dermis

Question 3

Ruffini endings

Adaptation
receptor field
type of detection
location

Answer 3

Adaptation = slow
receptor field = large
type of detection = stretch
location = deep in dermis

Question 4

Meissner’s corpusces

Adaptation
receptor field
type of detection
location

Answer 4

Adaptation = fast
receptor field = small
type of detection = tactile sense
location = superficial

Question 5

merkel’s disc

Adaptation
receptor field
type of detection
location

Answer 5

Adaptation = slow
receptor field = small
type of detection = steady touch
location = superficial

Question 6

define adaptation

Answer 6

how quickly recepotr responds to changes in frequency of stim

Question 7

fast adapting receptors produce ___

slow adapting receptors are __

Answer 7

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

Question 8

usefulness of

fast adaptation vs slow

Answer 8

fast = impt for sensing textures and vibrations

slow = correlate with intensity of stim (stretch = Ruffini and pressure = Merkel’s(

Question 9

receptive field define

deep vs superficial

Answer 9

area over which receptor stim

deep = large field and respond to wide area

superficial = finer tactile discrim

Question 10

flow info for fine touch sensation and propioception below head

Answer 10

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

Question 11

flow info for fine touch sensation and propioception from the head

Answer 11

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

Question 12

define somatotopy

Answer 12

organization of body map on cortex for carry and receive info from particular areas of body

Question 13

what does it mean when some areas of map are larger than others

Answer 13

more extensive innervation (hands and feet)

Question 14

different areas of somatosensory cortex receive or relay info on __-

Answer 14

different types of sensation

Question 15

how is there parallel maps?

Answer 15

each area of cortex repeats somatotopic maps so multiple parallel maps each correspond to distinct sensory function (touch, propioception)

also comm with motor cortex

Question 16

brodmann area 
3a = 
3b = 
1 = 
2=

Answer 16

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

Question 17

describe cortical barrels/columns

Answer 17

barrel = vertical slice that contains neurons all of diff groups (differ in modality, receptive field location)

Question 18

functions of different layers of cortical barrel

1
2
3
4
5
6

Answer 18

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

Question 19

guillan barre

CSF content?

Treatment?

Answer 19

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