unit 2 review - somatosensory Flashcards
what are the 3 divisions of the somatosensory syatem?
exteroreception
enteroreception
proprioception
what does extero reception include?
nociception
thermoreception
mechanoreception
what are the 4 types of mechanorecpetors on the skin?
meisseners
merkels
pacinian
ruffini
name to receptive field size and adaptation kind?
of the 4 mechanoreceptors
meisseners
- small, rapid
merkels
- small, slow
pacinian
- large, rapid
ruffini
- large, slow
what does rapid adaptation mean?
fires AP when stimulus is first placed and when stimulus is first removed
what frequency is each corpsucle best for ?
pacinian=high
merissners=low
describe mechanoreceptive channels?
all have unmyleinated axon terminals
- membranes of the axons convert mechanical force into a change of ionic current
what do primary afferent axons do?
where are the cell bodies of these axons located?
bring information from sensory receptors into the CNS (spinal cord)
- cell bodies are located in the dorsal root ganglia
what are the 4 types of axons?
Aalpha, Abeta, Adelta, C
what do the 4 types of axons correlate with? mylein wise
Aalpha, Abeta, Adelta, C
most myleinated to least mylenated
Aalpha info?
proprioceptors of the skeletal muscle
Abeta info?
mechanoreceptors of the skin
Adelta info?
pain and temperature
C info?
temperature, pain anf itch
what axon types go through the DCML?
Aalpha, Abeta
what type of information does the DCML carry?
epicritic
- touch and vibration (no pain or temperature)
describe the pathway of the DCML?
1) first order sensory afferents enter spinal cord through dorsal horn (grey matter)
3) travel up spinal cord through (white matter)
4) projects to S1
where is the DCML first synapse?
dorsal column nuclei
where does the DCML decussate?
medial lemniscus in medulla
- high
where is the DCML second synapse?
ventral posterior lateral nucleus
what is not part of the DCML?
face
what happens when you lesion above the medulla?
below?
above=loss of contralateral touch
below=loss of ipsilateral touch
where is S1 located?
where do those inputs usually go?
parietal lobe
- layer IV/4
layer IV of S1 has two components?
name and describe them
area 1 = texture
area 2 = size and shape
what are areas 5 and 7 concerned with?
intergration of the senses
- movement planning, attentiveness
damage to 5 and 7
what is agnosia?
inability to recognize objects
neglect syndrome?
happens contralaterally,
- will neglect everything on a side of body
describe the meilenation of noiceceptors?
unmylenated
what are the axons associated with slow vs. past pain?
slow = C axons
fast = Adelta axons
what information does the spinothalmatic pathway carry?
protopathic component
- pain, temp, itch
what fibers go through the spinothalamatic pathway?
Adelta and Ac
describe the spinothalamatic pathway?
1) axons from dorsal root ganglia enter dorsal horn
2) ascends up the spinal cord to the S1
where does the spinothalamatic pathway first synapse?
in the substantia gelatinosa
where does spinothalamatic pathway dessucate?
immediatley in the spinal cord
- very low
where does spinothalamatic pathway synapse for the second time?
contralateral thalamus
- intralaminar VP nuclei
what are the 4 sections of the spinal cord?
cervical: neck and arms
thoracic: torso
lumbar: legs
sacral
describe is primary vs. secondary hyperglesia
primary=at site of damage
secondary=around site of damage
what does substance P do?
increases inflammation
- relates to secondary anaglesia
what is the descending pain control pathway?
1) periaquaductal grey signals raphe nuclei
2) affects noiceceptive inputs in the dorsal horn of the spinal cord
pathway can be activated by emotional factors or opioids
